Got a question?
Here is a paypal button for $10 Quote Consultation Fee. This covers my time in phone or email communication. Speaking writing and download/upload photos takes time. I charge for my time and services. This $10 does not apply to any parts or services and is non-refundable. I find that this tends to screen out 99% of emailers/callers. The 1% of emailers/callers are my buyers. I reserve customer service and technical answers to buyers only. I reserve the right to say no thankyou or to charge more due to the complexity of the question etc. I perform repairs and or diagnostics service for -circuit boards/parts etc. BUT no repairs and no diagnostics testing services are included in this $10 Quote Consultation fee.

Dr Virago Pete's Electronic Parts Testing Service

Send your desoldered components ready for test

1. Desoldered

2. Wrapped carefully

3. Return envelope and postage affixed

Solid state & Semiconductor Components I can Test

1. Transistor

     a. NPN & PNP

     b. Mosfet

     c. IGBT

     d. Power

     e. others

2. Diode

    a. Germanium

    b. Silicon

    c. Zener

3. Capacitor

    a. Capacitance

    b. ESR

4. Inductor

5. IC Chip

    a. TTL Logic Chips

    b. 7400 series chips

    c. 5400 series chips

    d. 4000 series chips / CD4000 series chips

    e. HEF400 series chips

    f. 4500 series chips

    g. ULN series chips

    h. others

6. Voltage Regulator

    a. 7800 series

    c. 7900 series

7. Varistor

8. Optocoupler

9. Solenoid

10. Surface mount components / SMD.

11 Analog Chips

This ad is aimed at the DIY student or hobbyist who is working on his/her own electronic device and needs assistance in troubleshooting.

Consumer-level meters simply do not have the ability to thoroughly test solid state electronics. For example the average multimeter can only test Volts and Ohms.

Intermediate level meters can check capacitance but not ESR. These intermediate level meters can test transistor gain but not leakage. This leads to frustration in the student or DIY repairman/woman because they are looking for a fault they cannot find.

I have professional test equipment which can thoroughly test components you send me for test. Most components on a PCB are soldered in place. You must carefully desolder components before sending them for test. 

Identification of Unmarked components

1. Scratched off markings

2. Worn ratings number

3. IC chips

I am looking for a  "U-TEST-M" vacuum tube tester made by Colonial Merchandising model 2500 and when I purchase one - I will update this ad to include vacuum tube testing service also.

I am looking for a "Linear IC Tester" or "Universal IC Tester" and when I purchase one or more I will add this to my list of chips.

There are many parts I have in stock as replacements and some that I do not have in stock. I also have many books which show the ratings of thousands of parts. I can also cross reference substitutes and replacement parts.

I can identify a replacement/substitute for most parts.

What Makes Dr Virago Pete Qualified?

1. I own many parts checkers and testers

2. 30+ years experience in troubleshooting electronics

3. Former Electronics Instructor


1. Always put your IC chips in sockets when building a kit

2. If your device runs on batteries - dont run off power adapter

3. Use a correct soldering iron 15watts or less

4. Learn to desolder quickly without overheating your parts.

5. Take a detailed photograph of your PCB and make notes and sketches before desoldering anything from the board.

6. Don't tinker - do it the right way - or don't do it at all

Contact me if you need chips or other electronic components tested. I try to be reasonably priced. Many electronic devices made in the 1970s, 1980s, 1990s, 2000s, 2010s used off-the-shelf stock chips for all or a portion of their functions. I can test these industry-standard parts.

What I'm trying to say is - when you are repairing a device - finding the 1 bad component - whether it is an IC chip or other - you hope that it will be a common part that failed - one that you can easily replace and is readily available. Most likely your device has failed in one or more common parts - cheap to replace - but the trouble is - in identifying which one has failed.

The number one cause of failures in electronic devices is electrolytic capacitors (sometimes obvious due to the bulge) and sometimes tantalum capacitors will spontaneously cease to function or pop/explode - as these can fail quickly - sometimes while letting out a very foul smell unique to a dying tantalum capacitor (several aerospace companies refuse to use tantalum caps in their space missions)

I can test capacitors with my professional ESR tester. Bad capacitors do not always bulge. Sometimes electrolytic capacitors will make a loud POP like a firecracker as it is dead - bulging the top or not bulging the top. Most failures are not dramatic and make no noise or smoke or smell. Equipment is necessary to identify these bad components without visible clues - which is where my expertise comes in.

Dr Virago Pete

(847) 454-7858 between 11am and 7pm daily

email address

Located in Illinois USA

My assistance is not free - reasonable fee - call to inquire.

I use quite a few desoldering methods and decided to add some insights about my Soldering / desoldering equipment. I normally use a Radioo Shack desoldering iron with red bulb for my everyday desoldering of parts, but occasionally I will have a particularly stubborn or delicate part and I am always looking for alternative ways of desoldering parts. 

I have the following Soldering / Desoldering equipment

1. Radio Shack 15/30 watt switchable soldering iron (the one I use the most) 120V I have went through a few tip as they tend to get eaten away by solder and flux. I also use a fine metal file to clean it up when the tip gets nasty. I like when the tip gets short as it heats better. When the tip is new and long it doesnt heat as well as when it is short. I dont often sharpen the tip - only when I have a very delicate soldering job like high-pin-count ICs. The tips unscrew so it is possible to change between semi worn tips and brand new ones. I usually keep a spare tip in my soldering tool box. Previous to this I used a gun handle style soldering iron from Radio Shack approx 30 watts which I liked also but burned out after 10 years of use - not a bad reflection of the mfg at all.

2. Radio Shack 45 watt desoldering iron with red rubber bulb (the one I use the most) this is my second unit as the first one burned out after 15years of regular use which was very reliable and hardworking. 120V I have went through a few tip as they tend to get eaten away by the solder and flux over a long period of years. I usually keep an extra tip in my soldering tool box.

3. Radio Shack Portasol Butane soldering iron - purchased used (tip burned out after 10 years of regular use - I bought an aftermarket brand new in the package Boardworks tip for it (with slots rather than original keyhole shape - and the slotted tip burned out after 1 week of light occasional use) I still have not ordered a replacement original tip as I dont want to keep throwing money at this tip replacement issue - which the tips are expensive. Was very useful for soldering PCB with very large amounts of solder or where high heat is needed - like to reattach coaxial connector on RF shield - where a normal soldering iron just doesnt have the muscle to heat. I like this unit and the burned out tip isnt a bad reflection on the mfg as I got 10 hardworking occasional use years out of that standard tip that it came with. 60watts approx heat output with standard tip. I replaced the flint with a standard Robinson lighter flint as it was worn out from my use and the previous owners use. Update 10/4/16 I have purchased a set of 4ea tips for Portasol and to my amazement - the brand new soldering tip didnt work good after 3-4 soldering sessions - making sooty big flame when lit, sputtering, not glowing red hot, flakey and difficult to get it to work - WELL here is why and how I fixed this issue. See Butane turns into water as a chemical reaction. Over time (my Portasol is over 10years old and used very often - NICE TOOL) there are water droplets/trapped air etc inside the unit. I fixed my unit to much improved but still not perfect condition by using a 1/8" metal rod (Dremel tool end shaft) to push up on the butane fill valve. FFFFFFSSSSSSSFFFFSSSS the butane sprays out the bottom (wear rubber gloves) and this pushed out the water and air. The next time I used the Portasol - it worked and lit much better. I may have to repeat this step to fully get out the contaminants. Dont get me wrong I really like this soldering iron. Its not the fault of the unit or the butane from the hardware store. Butane itself turns into water and collects inside over time - just like a pair of glasses gets condensation coming into the warm from the outside cold winter air. Butane is a gas and gets compressed- when sprays out - it is very cold- thats where the water comes from combustion and also the cold/hot/cold/hot ... condensation.

4. Tenma desoldering tweezers 21-8230 purchased from big-auction site) and I made a few custom-made tips to remove ICs with it. 45watts 120V I like the dual soldering iron design and see my other page for the tips that I custom made for my unit.

5. Hakko 470 desoldering station with 803 gun (I bought used and doesnt work quite right- temp adjustment even on highest setting doesnt melt some high temp solder but still work fine for normal good type solder but heating could be better - possibly needs adjustment or a weak/worn electronic component inside) This is not a bad reflection of the mfg as it is 20+ years old and Im not the original owner - I have a spare gun and purchased some oddball things it was missing from big-auction-site like solder reservoir spring, and ceramic filters. These little parts are very expensive and I was glad to buy this used unit for a low price on auction- but the little missing/replacement parts pieces add up very quickly in cost. Most electronics enthusiests are nortoriously little-or-no-cost $ spenders. 120V adjustable heat

6. Weller blue adjustable temp Soldering Station WSD80 - in disrepair/disassembled - purchased it that way from an online auction. A restoration project I hope to find time for. It looks like a good unit and the disrepair is not a bad reflection of the Mfg. It is over 15 years old and who knows how much the previous owner used it? My hunch is it is approx 80watts max of heat with the iron I have and is temperature adjustable. I dont know what is wrong with it at this time as it is disassembled and never been plugged in by me.

7. China Imported Blue/White desoldering iron solder sucker 220v 30Watt - never used as it runs on 220v not 110V

Update 5/5/16

I recently purchased a very inexpensive desoldering iron with built-in solder sucker pump (see picture blue/white unit above) and decided to purchase from a California big-auction-site seller. I received the unit in about a week and was just like some of the youtube videos which shows the product. I decided to disassemble the electrical cover just behind the push down lever and I see 2ea bare wires (just like the video) and I also measured the ground aligator clip end and I see no continuity between the hot tip and ac prongs or ground wire - I checked every combination. So the alligator clip ground is non-fuctional. I also spent time researching this item in forums and on youtube videos and there seems to be some confusion on whether this advertised 220V 30W unit works on standard household 120V (as it does have a normal 120V plug) and so I plugged it into my household ac outlet (measures between 123V to 126V AC typically) and the unit does heat up but never sufficiently to melt solder- even after leaving it for an hour. So it gets hot enough to burn your hand but not enough for solder melting on 120V. I was also under the wrong impression by the ad that it runs on normal household ac - but I did see the 220V in the ad also. So to put aside the confusion, I am posting this short article about it. I am still glad to have it even though I have not actually melted any solder with it. It came with a cleaning rod and 2 total tips - one with a fine time and one with a bigger hole. I plan on buying a small travel power adapter which converts 120 to 220 AC to use with this unit. Alternatively, I could disassemble and add nichrome wire in the correct amount to make it standalone 120V but I think I will just buy a cheap small travel adapter as a better solution. Maybe in the future they will make one that runs off of 120V standalone.

You would think that a 220V 30Watt de-soldering iron running on 120V would be a 15watt - BUT NO - it is not like that at all. It simply does not heat sufficiently at 120V. This is not a fault of the mfg but rather a miswording of the advertisement. The only fault of the mfg is the ground alligator clip which is non-functional. Frankly - few soldering irons have a ground wire and are mostly 2-prong. So having a non-fuctional alligator clip leaves me to either snip it off or attach it properly or leave it as-it-is. I havent decided on that part. For now I put it back in its package and will just add it to my close full of electronic gear and parts and stuff- which I use on special occasion. I was planning on using this to fix a particularly stubborn power inverter where the through holes are barely big enough for mosfet legs to squeeze through and they used hard to melt junky solder. I was hoping to find a better desoldering method for these difficult oddball boards - but alas this desoldering pump iron combo wont work on my 120V ac outlet. So until I get a step-up transformer of some sort- I cant actually use it. I only paid a few dollars for it- so Im still glad to have it and someday I may wish I bought a spare - who knows I may find a use for it. No holder was included and it seems to be balanced where if I lay it on the table - the tip doesnt touch the table - but still I will use a small Radioshack bent-piece-of-sheetmetal style soldering iron holder which I already have.

I see that some USA sellers have a "Tenma" model which is Yellow and White - and is probably color coded - Yellow unit for 120V and Blue unit for 220V. So I probably just bought the wrong color. Read the ad because it is possible that the color of the unit does not always match the voltage.

I like to use the bent piece of sheetmetal style soldering iron holder as it has very little contact with the hot iron and so doesnt rob the heat from the iron. I also have a Weller holder and soldering iron which is not functional and I bought it disassembled (previous owner repair attempt?) from a big-auction-site - but have never attempted to repair it - not enough time in a day/funds to get to all projects unfortunately.

I dont leave my soldering irons & desoldering irons running idle - I unplug them when not in use and plug them in just as I need them - letting it warm up for 10-15 minutes before use. This prolongs the heating element life and saves on utility bills cost- that is my personal view and you may disagree - as some people feel leaving electronic equipment like computers on prolongs their life (I disagree) and that the power cycling on/off is what actually shortens the life of equipment. You can have a different view - no problem. I always unplug my electronics when not in use.

Update 5/19/16

After about 10 years of having purchased and not assembling a used Weller WD80 soldering statiion (purchased nonworking and disassembled) I decided to work on it today. I cleaned all the individual parts using a bottle of dilluted green cleaner and water and spray bottle which I used for that cleaning fluid. I noticed that the previous owner boogered up some parts like the digital temp buttons are mashed and solder dings and the case has been exposed to alot of flux over the years and is splotchy- but I cleaned it up and looks better than before but not perfect. The transformer is mounted to the case bottom and plastic had a crack so i switched the ground wires to a screw closer to the the front of the unit which allows the back screw to screw down further and grips the remaining plastic hole and holds the cracked case better. I bent the sheetmetal heatsink away from the board - to a 90degree angle. I used my Capanalyzer to check all the capacitors and I did find one SMD electrolytic which had an ESR of 10 and an adjacent identical which measured 3. But I left it alone. I also checked the diodes SMD style and found none that triggered the ESR meters alarm. I used my Fluke 73 multimeter in diode check mode to check all the diodes and found none shorted and I also checked the 2ea TO220 package devices (possibly transistors- I didnt need to check) for shorts between legs and found no shorts. At that point I reseated all of the clips to make sure good connections. I also removed the fuse from the AC rear plug jack. The fuse tested good removed. I reinserted after bending the fuse holder 2 pins straight as it was a little cockeyed. I used the Fluke meter's continuity check to systematically check the AC prong and input lines to make sure fuse and continuity from AC cord was valid. I powered the unit up disassembled - making sure nothing electrical touched while live. I found that the Weller WD80 does not power up while the soldering iron is not plugged in. When I powered off and connected the soldering iron - then repowered on - then the digital display lit and the soldering iron heated and maintained whatever temp I selected. I carefully bent the heatsink back to straight and reassembled. Later that day I used it to desolder some N-Channel surface mount FETs from a non-working motherboard and tried various heat settings from 500-700.

Update 12/20/17
I have decided to purchase a handheld hot air tool today GJ-8018LCD purchased from China seller on Big-Auction-Site. It was a pretty good deal at $34.57 for the 110V 200watt version, and I look forward to receiving it. I have an upcoming project of replacing some surface mount components for a 3000watt Power inverter for someone and this is a good time to add this tool to my vast tool inventory. The miniature surface mount components were provided by the mfg and if it were just one or two- I could get by without this tool. But due to quite a few that need to be replaced- this time saving tool is necessary. Also, I am interested in plastic welding- and this looks like it could be suitable for plastic welding rod for repairs of big plastic items such as car bumper, garbage can, snowmobile hood, etc. I dont work on those type of things- but I have been thinking about disassembling some motorcycle batteries that have a bad cell- so being able to weld the case back together is on my mind. Also, I decided to replace my non-working Radio Shack Portasol (very trusty for many years but died awhile back) with a $30 Portasol P-1 I found brand new on Big-Auction-Site. These purchases are a splurge since the upcoming project covers these costs - and will come in handy to perform the repairs on the 3000w power inverter. The Portasol is especially good at heating large solder islands - which smaller soldering irons have a really hard time with. I like how my old Portasol made a nice neat job of smoothing out the large amounts of solder on these BIG areas of solder - very pretty end result.

I have had no-problems-that-come-to-mind about ordering directly from China. The parts and supplies and equipment are usually pretty good, decent and just what I expected. I see some youtube videos about repairs about this item. Hopefully, mine will last a good long time. After watching some videos about this GJ-8018LCD unit- there was one that mentioned the need to observe correct shutdown procedure- turn temperature dial to lowest setting and internal fan to highest setting - just before you turn off power switch. This is to evacuate all or most of the heat from inside. Otherwise the heat has nowhere to go when it is powered off abruptly.

Update 1/22/18
There is a decal on the unit which states - to let the unit cool down to 30 degrees C before you turn off. I suspect that if you shut off with inernals hot - that you would melt something inside - like the case and or fan etc and cause severe damage. I have experimented with my fixed unit and works fine now and I let it cool down to 26 deg C before I shut down- this caused no harm and the next time(s) for using it - worked fine.

It is my experience that SMD chips and SMD components usually dont go bad too often. I havent run into a big need for a hot air station or hot air tool. Usually in those equipment that I repair - it is some discreet/through hole component like transistor or mosfet or capacitor that has gone bad. But since someone is sending me their 3000W power inverter and a whole lot of parts they want replaced (the Mfg provided them all) then thats what have to do for that buyer.

Update 1/21/18
I have received my GJ8018LCD Hot Air desoldering/soldering tool and had some issues from the factory that needed repair. I think it is a worthwhile good tool. Unfortunately I got a bad one- unlucky for me - but I still recommend getting one.

I see a schematic on a video which helped me identify DB3 as a real part number (as I looked through the magnifier I was not sure if it was a D or a O or a B or an 8). I am not affiliated with this video- not my video.

I suggest opening it up to make sure to correct any mistakes in assembly. I have repaired it and my story/pictorial is herein these files. Contains photos, a text file, 3d printable hole cover STL file and CAD drawing of this part. I created this modification/repair Jan 2018.

My GL8018LCD Repair Part My GL8018LCD Repair Part
Size : 13704.479 Kb
Type : zip
My GL8018LCD Repair Part My GL8018LCD Repair Part
Size : 14591.316 Kb
Type : zip
GJ8018 PCB & Wiring  Sketch.jpg GJ8018 PCB & Wiring Sketch.jpg
Size : 1449.306 Kb
Type : jpg

Doma / Amscope Stereo Microscope (heavily modified)

I use a plastic stereo microscope which is Amscope model SE120 and has 20X magnification. It had a strange design in which I feel it was made Backwards. So I cut it in half carefully and made it Normal.

This microscope was purchased in 6/2018 brand new directly from Amscope (Arrived in a crinkled Doma 210 box.) There were other no-name for the same price, but the photo showed this unit with the rubber eyepieces - that was the deciding factor in going with Amscope. I dont know whether the no-name units came with rubber eyecups or not.

I modified it the same day I received it using a 3d Printing Pen and light gray ABS filament. The body of the microscope is white and I used ABS filament which I already had. I wasnt worried about a color match. I made a big ugly weld and went over and over and over as I wanted it to be super strong. Im sure the DIY weld is very ugly and very strong.

I used a dot placed on the stage as a target (piece of tape with a magic marker dot) - welding the plastic and comparing the dot often to see if it is in the center. This took several tries to get right and I ended up cutting my own plastic welds and re-weldind it until it was centered. This tedious process took about 3 hours and Im pleased that I have a nice straight level NOT-BACKWARDS-ANYMORE microscope. I specifically purchased this to reCAP a Panasonic DVCPRO50 VTR that I own that was just FULL of Bad SMD electrolytic capacitors. In the waiting period for the arrival of the microscope, I have re-done most SMD caps with just a filmstrip projector lens- but was very tedious. I will be using this microscope from now on.

Amscope SE120 (heavily Modded) has a bright single LED and runs on 2ea AA batteries (supplied). I even modified the styrofoam box - so the same microscope fits into its original crinkled DOMA 210 box when not in use. THUMBS DOWN ON A BACKWARDS microscope that came in a wrinkled box with a different brand. I corrected it to be NORMAL and now works good and feels good. The rubber capstan-style up/down movement doesnt hold the position as firmly as I would like. For now it is good enough and holds up/down position good enough to solder/desolder.

I see the very same big-auction-site ad where I bought mine a week ago - it shows qty 810ea sold so far and seems to be a very popular microscope. I wonder if Amscope is a re-brand or the actual mfg?
I see the same microscope "Aomekie" "Amscope" "Doma" and some no-names. My box shows "DOMA 210" I have created this image using Microsoft Paint on a Windows XP laptop. The gray blob represents my plastic welding using 3D Printing Pen and ABS filament.

Here is a photo pictorial of my Modification to the microscope. See the above photo shows the eyepieces are facing the wrong direction. My microscope has the eye pieces facing the other way now (took me 3 hours to fix it) and the ZIP files show every step.

Update 8/18/18
As a result of extensive SMD capcitor replacing and using this heavily modified microscope, I have become painfully aware of the shortcomings of using SMD solder paste. Previously, I just thought it was a liquid that had te color of solder and magically turned into solder when heated- this is now VERY aparent to me to be false. As I look at my soldering under the microscope I see that the paste is actually tiny balls (like a bottle full of BBs or ball-brearings and it has a poor quality flux that evaporates and dries out- this flux is unlike traditional soldering flux. The SMD Flux Sucks!!!!! The microscopic balls fly everywhere when you put your soldering tip to melt it. Under the microscope it makes a big mess. MESS MESSS  MESS I couldnt believe what I saw under the microcope at 20X magnification. Wiping the excess SMD solder with a cotton swab just smears it everywhere.

To the naked eye, soldering SMD is nice and neat and clean- but under the microscope - I see that it throws microscopic lead balls everywhere on the board and more. Also as I view youtube soldering videos - I am noticing that this happens to everyone and they are oblivious to the lead balls flying while they are soldering SMD. As I watch closely in these online videos I see these solder balls flying and the authors are oblivious.

I havent read or seen ANYONE addressing this issue.

My solution is to vacuum these ridiculous solder balls using a 3d printed attachment for a small Shopvac.

I will chronicle this further down on this page.

Amscope 120 Backwards Mod Amscope 120 Backwards Mod
Size : 11075.551 Kb
Type : zip
Amscope 120 Backwards Mod Amscope 120 Backwards Mod
Size : 10220.89 Kb
Type : zip

Vacuum Cleaner Attachment for SMD Solder Ball Cleanup

I have designed and 3d printed the following items using freeware Solvespace and an older Windows XP laptop. I printed them in ABS on a heavily modified Alunar R100 3d printer with a cardboard pizza-box enclosure and Add-on heated printbed. I printed these pieces solid and .1mm resoolution and Elmers Purple gluestick on a plain aluminum heated bed. I used Cura to generate my G-code. My process is painfully slow but gives wonderful results.

I have included one photo showing the hose attachment and interconnects/couplers for as many BIC pen tubes as I need. Sometimes I use this for cleaning hard to reach machine internals. Sometimes I use it to clean circuitboards Im soldering SMD which throws alot of microscopic solderballs everywhere - even in between solder legs and hard to get to places.

The bic pen tube tip can be with or without the black or blue pen tip. For cleaning microscopic SMD solder balls - using the black or blue pen tip allows for a much smaller vacuum hole- and hence more powerful suction in a small spot.

I dont know where the balls go when sucked up inside the machine- it would be good to invent a solder ball catch filter etc which goes inside the vacuum cleaner. I dont know if the vacuum cleaner bag will catch these tiny solder balls. I dont know whether the vacuum cleaner with throw these solder balls everywhere in your room. Some vacuum cleaners have a bag and others do not. Use your own best judgement on whether this is right for your application or not. Spewing tiny lead soldering balls in your lungs and all over your room - is not what I want for you. Be safe.

Be aware that lead solder paste is absolutely packed with tiny lead balls which get sprayed everywhere as you solder. All over your hands, clothes, floor, walls, PCB, etc. Look under the microscope and you will see Im right.

Use at your own risk.


Electrolytic Capacitors go bad and are the #1 Cause of Failure

(My Personal View)

Electrolytic Capacitors have a rated lifespan of approx 1000 hours or in the case of highest quality electrolytic capacitors 2000+ hours rated. Multiply 24hours in a day x 30days in a month and you get = 720 hours in one month. So really 90days is the rated life of any device which contains electrolytic capacitors. That is one reason why Manufacturers only offer a 90 day warrnty on TV sets etc- if you leave your TV set on continuously for 90days straight - it will most likely survive 90days without fail- so the mfg is fairly safe offering a 90 day warranty.

It is amazing that so many devices lifespan is greater than 90days - it really is not supposed to last that long. Care in handling and not letting a device get too hot - helps extend the life.

My point is that I always unplug my devices when not in use - any device - especially one where it contains capacitors.

24hours x 30days = 720 hours in a month

3 months x 720 hours = 2160 hours in 3 months

There is some truth to power cycles shortening the lifespan of a device. But I still turn my devices fully off when not in use. Some devices have a standby circuit waiting for a remote control command or a pushbutton command to fully power on- but still a portion of that device is on - even when it is "off" My personal view is - it is better to fully unplug it (or switch off power switch to the outlet or power strip) to prolong the lifespan of the device.

Not too many modern devices have a true on/off switch on the back or side - to fully turn it off. So some part of that circuit is powered on even when "off"
Eds88Aom.pdf Eds88Aom.pdf
Size : 112.445 Kb
Type : pdf
EDS Capanalyzer ad.JPG EDS Capanalyzer ad.JPG
Size : 301.264 Kb
Type : JPG

The above is an ESR tester - EDS-88A CapAnalyzer (Series II) which tests ESR (equivalent Series Resistance) for electrolytic capacitors and other types such as tantalum and more. The above file is the user manual. My ESR meter is the EDS-88AII which is a slightly more recent design. The LED bargraph display is easy to read and the alarm sound is settable by the linear potentiometer for sensitivity. The best feature is its automatic self-discharge of capacitors. That was its biggest selling point to me and a big time saver. It will cycle through self-test and several other checks before each and every capacitor check. It is a quick machine and has found countless bad capacitors. An excellent ESR tester.

I already know where the bar graph LEDs should be for small through large capacitors so I dont need to refer to the chart anymore. I just know when the bargraph looks odd for a capacitor then I know it is time to change it. Also comparing the same size capacitor over the same to-be-repaired-board  will make a few stand out as being weak or odd functioning. It is a true in-circuit tester. Some bad capacitors show a led towards the bottom of the bar-graph or dont register at all. Slightly weak capacitors can be just a little higher or lower than should be- those are generally not the cause of a failure in equipment operating. It is the capacitors which deviate drastically that generally are the cause of equipment failure to function etc. I always check my new parts too because there are sometimes duds in brand new capacitors purchased in bulk.

Finding a bad capacitor is not about nit-picking if it is in the red or yellow or green area of the chart. A bad capacitor will be blatently bad. If it is not blatently bad then most likely - that capacitor is not causing your equipment to have failed to work.

A bad capacitor will usually be 2x or 3x or more - the rated esr of the rest of the caps you test which are of similar size/type. It will be blatently bad or will give a no reading or a alarm or be drastically different than the rest of the caps.

Cracked or bulged caps or caps which leak gunk (flux) or fluid (flux) are definitely bad and should be replaced- even if they test fine. Some capacitors are glued by the factory - dont mistake glue for leaking flux.

I dont recommend powering up the tester with the red button held down- this disables the self discharge feature (until next power off) because self-discharge is a protection for your esr tester. Touching a charged capacitor can kill the esr tester. Even though it takes an extra second to automatically discharge.

The tester needs no polarity as it functions with self-generated AC frequency and AC is non-polarized. What that means is that you can test an electrolytic capacitor either-way -either polarity of the black/red lead is fine and doesnt matter to the tester which way you connect it to the polarized cap.

It is important not to test huge capacitors with this tester. Just normal size or small capacitors as found in everyday electronic devices like TV radio computers and other ordinary household type equipment. It is not for big high-powered capacitors.

Capacitors generally have a 2000 hour lifespan. It is a wonder most electronics lasts longer than 90days because that is the warranty period. Capacitor's 2000 hour life is 90days. It is a wonder that devices like tv sets last longer than 90days. I always shut off my equipment and appliances and audio/visual gear & more when not in use. Why waste the life of your equipment - by just letting it run idle?

Runs on 1ea 9V battery. Purchased used in 2011 year. A similar tester is Capanalyzer Model EDS-88A

Some notes on difference between model EDS-88A and EDS-88A series II:

The series II has the words "Series II" written on the PCB. The series II uses 2ea PIC chips. The EDS-88A uses 1ea Pic chip and 2ea large LM chips. These 2ea large LM chips were replaced by 1ea PIC in the Series II. The components and layout are very similar. Identical functioning. I have seen a model EDS-88A with a slot cut in the back with a prop-up style holder (See picture file). My newer style EDS-88A Series II does not have this slot or holder.

I see a big-auction-site listing where EDS was cleaning out their inventory of spare parts on 6/22/15 and feel this partial parts list is very important in case of a need to replace blown components. I have copy/pasted this partial parts list here. The ad showed parts used in the Leekseeker89 and Capanalyzer.

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Several photos showing transistors, capacitors, diodes (above pictured) 

ECG Semiconductor Master Replacement Guide (Parts Cross Reference Book)

I received this book for free from a local electronics store that I used to buy parts from regularly in the 1990s. That store is now closed and the remaining branch is too far away to drive to but I occasionally mail order from them still. This book is old and the tattered pages and cover are taped back together. I use this book often. When I suspect a part is bad - I look up the part number in this book and it tells the specifications of the cross reference part in great detail. At the front of the book - a list of available replacement semiconductors is handy. It also contains drawings of pinouts.

ECG parts and NTE parts share the same part numbers and specifications - so when I find that I need a replacement - I will look online or call local electronics stores with a part number. I tell them it can be ECG123 or NTE123 for example. I sometimes can find a replacement part still in its package unused on big-auction-site. It is amazing that one little part can cost 2-10+ bucks each and even so the repair of that device for $10 is money well spent and very cost effective. I sometimes look for a reverse cross reference so I can broaden my options when buying a replacement part. There are millions of numbers that truly are the equivalent part. This book narrows down those millions of numbers down into several hundred part numbers.

The main pupose for this book - for me - is to compare questionable parts and decide if the part is still good. This book has saved me from buying a large quantity of replacement parts over the years. I can key-in on only buying parts that I know are truly in need of replacement.

My cat starting digging at this book 5 years ago and luckily I caught it just in time - before she tore it to bits. The cover and a few pages-in are now taped back together as best as I could. The holes are due to my cat. The worn out pages are due to my extensive use of this guide.

BK Precision model 815 Parts Tester
I purchased this tester approx 1997 brand new and been using it for over 15 years. This tester is a full service device and fully tests out-of-circuit/desoldered transistors, Diodes, SCR, LED, Resistors, Capacitors (Capacitance value only - no ESR), batteries, etc. This device helped me repair quite alot of electronics. The only test that it doesnt do is ESR which I believe this machine was made before ESR testing method was invented. I use this tester in conjunction with a 1996 edition manual to look up the cross reference value of nearly any semiconductor. Then I compare those specifications to what this BK Precision 815 Parts tester reads from the questionable part. I have purchased a few NTE and ECG replacement parts based soley on the readings of this tester. It has never let me down and is always correct. I have read alot of questionable parts on this tester and resoldered them back in circuit knowing that this tester proved the part in question was not bad after all. It has saved me from buying replacement parts un-necessarily. I can key-in on ONLY buying a replacement part which are for sure needed.

The above pictured tester shows a rubber protective cover. Mine was one of the first ones made and didnt come with that rubber cover. It still sells for the same price that it did 15 years ago. For the last few SCRs that I tested - I couldnt get my meter to over-range (the first 2 tests pass and the last test fails to over-range). So I ended up buying an SCR twice un-necessarily. I'm starting to think there may be a component inside that has gone bad. Fixing a tester is one of the hardest things to do. You need a tester to test a tester ... and if you rely on that tester and you only have one - then ... I'm not truly convinced yet that it doesnt work for SCR anymore. I will refrain from repairing that which works. It may be that those 2 SCRs fooled it or it may be that the tester has a bad part - I'm still undecided. If the reader has a suggestion on which internal component to check - let me know. The Duoyi DY294 shares many of the same functions - so I am able to test my tester with a tester ... LOL

I remember seeing a bright yellow Clone of this tester on big-auction-site. Unfortuantely I no longer have that photo.

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Above pictured Duoyi DY294 Transistor & Parameter Tester (Also Checks many other semiconductors and capacitors etc)

DY294 English manual download above (my tester came with a foreign language paper instructions)

This tester has some unique features which allow me to test parts I could not otherwise test. It also internally scales up the voltage for certain tests- for example it can generate over a thousand volts for certain tests yet only 4ea AA batteries power this tester. It tests alot of parts' parameters so it can be compared to book specifications. For example when deciding whether the part is good/bad - comparison of data found in ECG or NTE semicoductor replacement data books - comparing what you see on this tester can be compared with those listed in the ECG or NTE books for their subtitute cross reference part values.

Some tests for varistors or transistors with internal diodes can be checked with this tester. It is a very handy device for alot of things found in most everyday devices- which previously there was no easy way to test them that I know of. Care must be taken to set the dial correctly and not flip the dial after the part is installed otherwise you can expose a part to the wrong test and apply too much power to the part accidently. Keeping a notebook on how to test a part is important so you can repeat that test the same way next time too. The apearance of this tester is deceivingly simple. It is labeled as a transistor tester but it is so much more than that. It not only tests standard transistors but all of the oddball ones too and many more parts.  It is very versatile and performs odd-ball tests that my other testers dont do. There are a few tests that a few of my testers have in common.

On some tests the TEST button is pressed and on other tests the TEST button is not pressed. Read the specifics on whether that test requires the TEST button to be pressed. Note that when the TEST button is pressed - the red LED "HV" next to the TEST button - lights up.

Purchased brand New in 2012 year.

Update 12/14/15

I credit this tester in identifying the voltage on a hard to identify Zener diode. It gave me the voltage and reverse voltage - and was able to match the zener type based in its readings. I know of no other tester which could have provided me with this information. It is a great component parameter tester. Its extreme ability to actually generate high voltages and test components at their high voltage specs (in the case of the above mentioned zener diode 160V) is a very welcome feature. I have other testers whichg identify zeners but thopse testers are only for low voltage parts. This one is very capable. See "Zener Diode Test" on this page to see my procedure notes.

Duoyi DY294 Tester Notes

Test 4ea AA internal batteries condition

(no components connected) turn dial to the right "2a(Ic)" The display shows battery volt (4ea AA batteries at 1.5v each should give you 6volts or better - the tester will work with weak batteries on most functions but some functions require peak batteries to give accurate reading) It is not necessary to press any button with this test.

AC Adapter

6V DC 2A using the jack on lower righthand front panel. + is the center connector. When using the ac adapter - make sure internal batteries are removed.

Voltage Regulator Testing

78XX and 79XX etc insert in 321 holes. With 78XX the regulator faces towards me. With 79XX the regulator faces away from me. Move dial to "78xx" or "79xx" and press TEST button and read display volts. Internal 4ea AA batteries need to be strong for accurate results. For example 7806 installed correctly with good batteries installed will show 06.0V when Test buton is pressed. Make sure your parts legs are free of excess solder or it will "booger up" your test holes as it is a tight fit since the legs just barely fit through the holes.

LED Test

Turn dial to "10mA(Ib) NPN (Put long lead of LED in "C" hole. Put short leg of LED in E hole) The led will shine brighter in other dial positions but this lower power position is safest for the LED as you dont want to burn out the LED - just test it. 10mA is enough to light most average LEDs without harm. Over time/decades of use - some LEDs grow dimmer with age. I suggest that dial is turned without anything inserted. LED should be installed AFTER dial is turned so as to avoid higher power ranges which can damage lower power LEDs. Display shows turn-on voltage of LED. Putting LED backwards does nothing and LCD shows only internal battery voltage of 4ea AAs installed. Typical red LED will show 1.76V for example when inserted correctly. No buttons are pressed during this test.

Zener Diode Test

Use E and C holes. Set dial first before inserting part. Set dial to "200V" NPN. Insert zener diode into E and C. Stripe side = C hole which gives Breakdown voltage when you press TEST button. Insert zener diode with stripe side = E which gives Forward Voltage Drop voltage when you press TEST button. Remove part and move dial to ICEO NPN and then insert diode (both ways) press TEST gives ICEO reverse leakage current. Having good fresh AA batteries installed is important for accurate reading

Varistor "Operating Voltage" Test

If the Varistor's value is 300V or below then use 200V NPN setting.

If the Varistor's value is above 300V then use 1000V NPN setting.

(300V is not a misprint and 200V is not a misprint and 1500V is not a misprint)

Turn dial to "200V NPN" or "1000V NPN" depending on your varistors value (see above note) Locate the capacitance test socket located in the lower right hand corner of the tester. Warning - This is a high voltage test - keep your hands away and dont touch any part of the meter or varistor during test. After dial is set and you have inserted varistor into the capacitor test socket - then press TEST button. The display will show the "operating voltage" on the display. It may vary a little from that written on the part. Release TEST button. Set dial to off before removing varistor. Avoid electric shock by not touching any part of the tester or varistor. This test generates up to 1500volts. Be very careful. I know of no other tester which can test a varistors "Operating Voltage".

Varistors and Disc Shaped capacitors look similar - be sure you identify the part correctly. Only run this test for Varistors.

Polarized Electrolytic Capacitor "Withstand Voltage" Test (medium size or smaller barrel shaped caps)

Locate capacitor holes labeled C+ and C-. Move dial to 200V NPN. Insert the legs of the capacitor into the correct socket hole. The stripe side of the capacitor is the minus side. Read the capacitors voltage and write it down. The way the capacitor is inserted - makes the capacitors value as writton the capacitor itself - faces the wrong way - so writing it down helps you remember - not to exceed the voltage that was written on the cap itself. This is a slow test and takes awhile and is a battery hog - will drain your batteries. Press TEST button and keep it held down until your voltage increases to the voltage written on the cap itself. This meter only tests the "withstand voltage" of the cap. It does not test ESR. It does not test capacitance. I know of no other tester which can test a capacitors "withstand voltage". It will even test capacitors which have a couple of hundred volts "withstand voltage" value.

Remember to discharge the capacitor by shorting the capacitors leads together before and after this test to prevent personal injury from a charged capacitor. Dont touch a charged capacitor's leads or partially charged capacitor. A DC 6V 2A power adapter is recommended for this test (plug into DC6V receptacle located just above the capacitor test socket holes. Otherwise fresh batteries are needed for accurate test (remove batteries when using power adapter plug). Test will quickly drain batteries. A bad cap will not charge or the voltage will cease to climb or will stall or will hesistate. A good capacitor will climb steadily but slowly towards the voltage. Once you reach the voltage - then let go of the TEST button. Do not surpass the voltage written on the capacitor. For example - if the capacitor being tested is a 16V6800uF then do not exceed 16v - after it climbs to 16v on the display - be sure to release the TEST button. I dont know what the consequence of not releasing is - possible capacitor rupture or worse or tester damage or capacitor internal damage - unknown. I suggest only testing it properly.

Transistor PNP and NPN (standard types)

ICEO Reverse Leakage Current test

Turn dial to ICEO (either PNP or NPN depending on which type the transistor data sheet indicates). Use a datasheet or by cross-reference to a substitute candidate data - which legs are EBC or BCE.  Insert into the correct socket holes in the tester as appropriate BCE or EBC. Press TEST button. The display should read "000" to indicate that the transistor is not leaky. Anything other than "000" denotes leakage and the transistor is faulty. Remove transistor. Turn dial to off.

hFE (gain) test (3 tests gives gain at 3 fractional amps settings) - make sure your transistor can handle this amperes

Turn dial to hFE 10mA (PNP side or NPN side depending on datasheet specification) Use a datasheet or by cross-reference to a substitute candidate data - which legs are EBC or BCE.  Insert into the correct socket holes in the tester as appropriate BCE or EBC. There is no need to press TEST button. hFE (gain) is shown on display. Compare to datasheet.

Turn dial to hFE 1mA (PNP side or NPN side depending on datasheet specification) Use a datasheet or by cross-reference to a substitute candidate data - which legs are EBC or BCE.  Insert into the correct socket holes in the tester as appropriate BCE or EBC. There is no need to press TEST button. hFE (gain) is shown on display. Compare to Datasheet.

Turn dial to hFE 10uA (PNP side or NPN side depending on datasheet specification) Use a datasheet or by cross-reference to a substitute candidate data - which legs are EBC or BCE.  Insert into the correct socket holes in the tester as appropriate BCE or EBC. There is no need to press TEST button. hFE (gain) is shown on display. Compare to datasheet.

Example C2166 shows "023" which is a HFE gain of 23 at 10uA in socket BCE.

VCE(sat) Collector to Emitter Saturation Voltage (2 tests at 800ma and 2A - not all transistors can handle this amperes)

Turn dial to 800mA(Ic) (PNP side or NPN side depending on datasheet specification) Use a datasheet or by cross-reference to a substitute candidate data - which legs are EBC or BCE.  Insert into the correct socket holes in the tester as appropriate BCE or EBC. There is no need to press TEST button. VCE(sat) is shown on display. Compare to Datasheet. (be sure your data sheet shows it can handle this 800mA before testing) Batteries must be fresh for accurate results (otherwise remove batteries and use Ac adapter 6VDC 3A)

Turn dial to 2A(Ic) (PNP side or NPN side depending on datasheet specification) Use a datasheet or by cross-reference to a substitute candidate data - which legs are EBC or BCE.  Insert into the correct socket holes in the tester as appropriate BCE or EBC. There is no need to press TEST button. VCE(sat) is shown on display. Compare to Datasheet. (be sure your data sheet shows it can handle this 2A before testing) Batteries must be fresh for accurate results (otherwise remove batteries and use Ac adapter 6VDC 3A)

Diode (standard types) Reverse Breakdown Voltage

Turn dial to ICEO(2000uA) Insert diode into E and C (either PNP or NPN side of dial will work but - or + on display may be opposite) For example on 1N4003 diode turn dial to npn side ICEO(2000uA) stripe of diode goes into C hole. Non-stripe goes into E hole of test socket. Press TEST button. Display shows "000" leakage. Remove diode and reinsert opposite (stripe goes into E hole and non-stripe side goes into C holeof socket) Press TEST button shows "1252" Reverse Breakdown Voltage (weak batteries 5v) Remove diode and turn dial to off.

Dual Fast Recovery Power Rectifier

Turn dial to ICEO(2000uA) NPN side of dial. Insert middle leg into E of large socket. Touch side let to C raised metal contact. Press TEST button. Read display. Release Test button. Rotate Rectifier keeping the middle leg in E hole. Rotal so the other outside leg touches C raised metal contact. Press TEST button. Read display. Remove Dual Fast Recovery Power Rectifier. Turn dial to off.

(Note turning the rectifier such that the middle pin touches C raised metal contact and the outside pin (1 test for each outside pin)  goes into E hole. Press TEST button gives "000" display. Remove Rectifier. Turn dial off.

Example MOSPEC F12C20C gives "000" leakage result and "1257" and "1257" reverse breakdown voltage result (weak batteries 5v)

Transistor Parameter Testing Note

Basic Functional Testing transistors can be accomplished by Gain (HFE_ and Leakage for most  transistors and it will catch most issues. This next section is about advanced transistor testing "parameter" testing.

The parameters of a given transistor can be determined by inserting the BCE legs of the transistor into non-matching BCE combinations of the socket (BEC, CEB, EBC, ECB,  etc many combinations). This produces a wide variety of test results according the the mismatching of leg to socket hole mis-combinations. This "mismatching is not arbitrary and it is not done willly-nilly or random. Follow the below instructions step by step in order to see the transistor "parameters" (I will document this later - to be continued)

To Be continued at a later date

odd transistor types
high voltage non-polarized disc capacitors
AC filter capacitors

Too many to list (this is a work in progress)

HP 990B SMD tester

is a Resistance / Small Voltage / Standard Diode & Zener Diode /small battery / Capacitance (not ESR) tester which has built-in tweezer probes (and included add-on handheld probes). I use this occasionally when I work on surface mount boards with very tiny soldered-in components. The best feature about this tester is its ability to identify Zener diodes voltage rating value (not as accurate as my other tester but good enough to determine if a component is blown). Another unique feature is with the push of a button the tweezer tip polarity changes opposite which makes testing standard diodes simpler as the buttonpress allows testing a diode in both directions easily. 

For example when testing a brand new in the package 4.7v Zener diode this tester will give a value of 4.01V and .063 reverse. Good enough for testing purposes - to determine if a zener is good/blown.

It has the functionality of a VOM multimeter with some additional features ( for example like zener test ) - however it is only for small voltage sensitive rating parts - not for use on big voltages or powerful components. Runs on 2 AAA batteries Purchased Band New in 2012 year approx.

Update 12/15/14

I suggest removing the batteries immediately after use. My first unit  worked just fine for 1 day and one day later was found dead on a few but not all functions - and exchanged by a kind China vendor. I can only suspect the internal batteries caused some issue. I have had nothing but good service from my second unit, and I always take out the batteries. There is no on/off switch.

Fluke 73 Multimeter

This is a very old tester and works very well. I trust it to give me the correct display of Voltage AC or DC or Ohms or Amps or Diode Test or Continuity Beep. It is easy to use due to its autoranging and autopolarity. It runs off one 9volt battery which lasts for more than a year of my use. I own several multimeters or VOM meters but this one gets used the most and I keep it handy to test batteries and electronic components etc.

My Fluke 73 is dead-on accurate.
For example I noticed a year ago that my AC power was higher than it was supposed to be. I initially caught that over-voltage when I tested the outlet with a Killawatt meter (also very good) and then I doublechecked the voltage on my Fluke 73 - same reading. When I called the electric power company to report 126.5V AC from my outlets the lineman that arrived confirmed this fact and said that he also measured 126.5v AC and he said that it is high but still within electric company guidelines - no repair done to the line. (Illinois USA AC varies nowadays from 123 V AC to 126.5 V AC and it is a bad idea to plug in older appliances and electronic gear without stepping down the voltage to within range of what the device requires.)

The Fluke 73 is a professional tester and is trusted by many millions of technicians.

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Production Devices   Model 85 Transistor Tester - Tests small signal transistors both in and out of circuit - runs on one 9v square standard battery and gives a tone when a good transistor contacts its 3 prongs on the solderside of a circuitboard. NPN/PNP switch is manually set and correct EBC CBE ... orientation is manually set by turning the tester to contect the correct transistor solder trace. Made in approx mid 1970s and came with the rubber-boot style extension cable as shown. The above picture is a postcard. I purchased this tester in July 2014 and required quite a bit of cleanup as it was rusty and in disrepair. I am trying to obtain a replacement switch for it as mine is cracked due to someone pressing on the PNP/NPN switch as if it were a pushbutton switch and cracking it. It is a 3PDT (3 pole double throw with 9-pins ) switch with (center to center space 1-1/8") threaded screw holes which I have located one switch at a electronic parts distributor close replacement but the holes are not threaded so I am continuing to look to see if I can find one that is a better match. I am able to test it so I know the circuit works. It is functionally the same as the model 100 shown below which I also own.

It doesnt test all transistors but tests enough that it is a help when checking for transistors that are bad - without desoldering the transistor. It has a brushed metal round case that resembles a microphone. The back cap is a press-fit and inside is the tiny headphone-like speaker and the speaker is moved outside the case dangling to replace the battery. The plastic cap on mine is original but doesnt hold itself in place- the previou owner used a piece of electric tape for a press fit which was unbelieveably very very very tight. I used a piece of celophane tape as a spacer for now. A set screw would be a better way to do this.

It runs on 1ea 9V standard rectangle battery and I always take out the battery because there is no power switch.

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Production Devices    Model 100 Transistor Tester - Tests small signal transistors both in and out of circuit- runs on one 9v square standard battery and gives a tone when a good transistor contacts its 3 prongs on the solderside of a circuitboard. NPN/PNP switch is manually set and correct EBC CBE ... orientation is manually set by turning the tester to contect the correct transistor solder trace. Made in approx late 1970s or early 1980s and came with the prong style extension cables as shown - these extension cables plug into the back end of the tester - near the speaker. The 3-pin prong on this model is slightly flexible, and this 3-pin prong is at the pen-tip end of the tester. I purchased this used in July 2014 as pictured (the seller forgot to send the green card which I'm still trying to obtain)  The ad was on big-auction-site and the seller had 3ea testers and 2 boxes and 1 set of cables and one green card. I was specific in my offer - mentioning all the parts I wanted and my offer. I think 2 of these are enough for my needs - having both a model 85 and a model 100 and both being functionally the same - 2 of them are good enough - I didnt need the other ones (see pic showing all 3ea testers the seller had for sale). I still hope to get my green instruction sheet - the seller said he will send it 7/14.

It doesnt test all transistors but tests enough that it is a help when checking for transistors that are bad - without desoldering the transistor. Battery is accessed by unscrewing 2 screws and separating the case halves.

It runs on 1ea 9V standard rectangle battery and I always take out the battery because there is no power switch.

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AVO TT169 Transistor Tester - in-circuit or out-of-circuit

This tester works very well to locate dead or shorted transistors in circuit. It is a 2-handed IC tester. One hand is holding the body of the tester and pointing the sharp green probe and touching it to the BASE of the transistor (usually the middle leg but not always) and the other hand is holding the red/white probe and touching it on the EMITTER and COLLECTOR of the transistor. One feature I really like is that the internals of this tester are alternating back and forth between Base and collector - so it is not important to know which one is which while testing. The result is a blinking LED if the lowpower transistor is good. The blinking LED is due to the internals switching back and forth between collector and emitter on the red/white probe. This feature is a big time saver. I'm going to call this feature self-permutating as it hunts on its own for Emitter and Collector on the red/white probe.

Quickly scanning transistors is easy and can be tested in just a few seconds each. If the transistor doesnt flash then adjusting the dial to try and find a setting where a flashing LED is observed or switching the NPN/PNP switch is needed. If the LED flashes then the transistor passes the GO/NO GO test.

The manual shows how to test diodes and power transistors.

Some Words of Caution
The power jack is not for connecting power (runs only on internal 3ea AA batteries). The power leads which are colored with a black wire and red wire are not power leads at all. Never connect any power to the power leads. The red and black wires (and alligator connector) and power jack is for testing power tansistors. The red and black wires are not needed for testing small signal transistors. There is another typo in the manual - the lightbulb does not light up during self test - only the LED. The lightbulb lights flashes when testing power transistors and pass. Probe leads are very sharp and hazardous - CAUTION

It runs on 3ea AA batteries and I always take out the batteries because there is no power switch. Also The probe tips are very very sharp and hazardous. This tester was made in the 1960s and I was lucky to find in pristine condition in 2014.

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I use the above pictured IGBT & Mosfet tester when I test the high power IGBTs. It has three leads and alligator clips. The LED lights or doesnt light to show correct or incorrect operation of the IGBT when the red button is pushed. It is a nice easy way to functionally test these parts. Some IGBTs fail catastrophically (melted/burned etc) on devices --to-be repaired- but others fail and there is no outward sign that the part is internally bad. The click sound and the red light means it is a good part. I have run into bad parts - and the tester either stays lit or stays off or doesnt respond to the button press- which means the IGBT under test is bad. It can also functionally test Mosfets. Runs on 1ea 9V battery. Purchased Brand New in 2011 year.

Consolidated Electronics Inc Semiconductor Tester model PST-5000
Seacor  Semiconductor Tester model PST-2000 (pictured above)

(also written as PST5000 or Semi Conductor Analyzer. Also sometimes the company was written Consolidated Electric and their website was Con-elec dot com and I see it is down as of recently and their 800 phone number doesnt work and says "disconnected or no longer in service" as of 8/14)

I have recently (Aug 2014/ March 2015) purchased these used testers in fixer upper condition (disassembled and missing parts) Both are nearly complete with minor things missing such as 2ea power adapters and 1ea rear panel and 1ea battery pack. I have reassembled them and have plans to create a homemade power pack and ac charger as close to original as I can fabricate in my shop. I have enough parts between the two units to fully restore both by comparison.

Consolidated Electronics PST-5000 and Seacor PST-2000 are "sister" units - they bear a diferent namebrand but truly are alike in many ways.

The best feature is in-circuit testing of transistors, diodes, scr, triac, mosfets, and many other parts. For some tests the leads can be attached to the semiconductor in any order - it will self permutate the test leads and display the pinout and identify the attached part. The display shows a text description and pinout. At powerup it performs a self test for 30seconds. The testing is performed by holding down the test button for approx 30 seconds after which the test results are displayed. There are 2 tests available Primary Test and High Voltage Test (a third onboard function is voltmeter). It must pass both tests for the part to be "good"

I look forward to the completion of the homemade battery pack - 2ea internal 12v DC packs (10ea x AA Nicad) as this will allow 4-8 hours testing time. The high voltage test puts the packs in series (24V). The Primary Test uses the battery packs in parallel (12V). Pressing the High Voltage test climbs the voltage supplied to the part being tested until it fails or passes (nonharmful to the part being tested - low current and autosenses any changes in the part). The PST-2000 has an upper limit of 2000V and the PST-5000 has an upper limit of 5000V. I dont foresee ever using the maximum high voltage capabilties as capacitors/other parts I test are no-where near that high voltage. Even so it is a very capable tester and easy to use for my low power/mid power component testing.

In many ways it is as easy to use as the "caseless semiconductor testers" that are popular as of this writing for less than $25 on big-auction-site (I have one too see elsewhere on this page - that one only works for out-of-circuit desoldered part testing). These PST testers perform high voltage tests and out-of-circuit and In-circuit tests - that is a drastic advantage over the inexpensive testers. The in-circuit testing capabilties are super great and IS THE reason I bought these. Well worth the effort and expense/cost to purchase and fix these 2ea formerly abused units received in disrepair.

Unknown mfg date and age - I estimate these were manufactured in the early 2000s and probably new costed more than I could afford.

I have tested both units with a makeshift power supply and both power up equally well and seem to be fully functional. My repair notes and photos are listed here.

Update 6/22/15
I went ahead and ordered some parts and pieces in order to complete my units. I ordered 2ea NiMH 12V 1800mAh battery packs, ABS 3/32" (.093")  textured sheet total cost approx $27 so far. I plan on cutting the ABS sheet to size to make a back panel - I will use a China 40W laser engraver to cut it cleanly. The 2ea NiMH battery packs are 2x5 arrangement of AA cells. I will snip off the connector (Tamiya RC style) and solder connect the original connecrtor and then heatshrink insulation over the solder joint. Battery packs from China take awhile to arrive and was a good deal at approx $10 each. I will order replacement battery packs for the second unit at a later date. This will allow me to do some testing on both units to make sure they operate fully and figure out the ac charging plug and voltage/amps needed.

(847) 454-7858 between 11am and 7pm daily

Dr Virago Pete

Update 6/25/15
I received 2ea 12V 1800mAh NiMH battery packs from China yesterday and have installed these in my PST-2000 battery pack assembly to replace the 2ea severely corroded NiCAD packs 12V 650mAh. The main thing was to remove the 4ea rivets securing the aluminum retainer which holds the batterys in place. I used a Dremel tool with a cutoff wheel to grind down the rivets backside (the aluminm side) and then when the rivet was flush with the aluminum - I just grabbed he rivet with a vise-grip and pulled the rivets out. I used 4ea 6-32 philips head screws and 4ea 6-32 nuts to secure the aluminum retaner using the very same holes which were previously riveted. THe screws allow removal of the aluminum plate for future battery pack replacement. SInce the rivets were placed so close to the bend- I had to modify all 4ea nuts to be very flat on one side- that way the nut sits right next to the aluminum bend. If I didnt grind the nut - then I wouldnt be able to fit it using the same holes. This is a nice elegant solution. I used a vise-grip to hold the nut while I useed a Dremel tool to grind it on one side. I also used some foam leftover from packing materials which hap[pened to be the right kind of foam. THe original foam had all kinds of dried gunk from leaking batteries. I put new foam inbetween the batteries - it is very much like original. The only thing I have left to do is cut the Tamiya style plugs off the new battery packs- and solder on the original plug with wires (scavenged off the corroded Nicad packs) and then heatshrink tube over the solder joint.
Im very glad it turned out so well - I was thinking about this for a long time and its nice to be so close to completion. I look forward to using my semiconductor analyzer.

The soldering is done - this was very critical as the polarity of the plugs needs to be correct - otherwise the tester can be ruined by hooking up the 2ea internal battery pack's polarity backwards. I double checked my notes and the red/black marker marks on my board. Heatshrink tubing was put on over the solder joints.

I ended up cutting the end off the Zip Drive 5V ac adapter and soldering it onto a 12V 1Amp ac power adapter wall-type. These ac adapters were purchased second-hand and so were expendable. At this time I have tested both PST-5000 and PST-2000 with the same battery pack charged for a couple of hours. They seem to work the same. I am charging the pack for a few more hours- I still have to figure out how many hours to fully charge. The battery packs as arrived from China had minimal power stored. One was at 11v and one was at 10.5v when they arrived. I tested that minimal power and it wasnt able to boot the PST units - but the backlight did light up with that little charge.

See my zip file containing pictures of this PST2000 battery pack rebuild here. 

PST2000 Battery Pack PST2000 Battery Pack
Size : 4156.592 Kb
Type : zip

Update 6/26/15

Im glad to have gotten pretty far along on the PST-5000 replacement battery pack. My 12"x12"x.090" ABS sheet arrived today and I looked through my inventory of metal and plastic cutoffs and pieces I scavenged off of misc things a long time ago. I saved a scrap piece of aluminum in my inventory for years - I dont know what it came off of originally - probably a scavenged for parts old dot matrix printer. Years ago people threw tons of crt moniutors and dot matrix printers in the trash and I scavenged some for parts and gears and motors and screws and nuts/bolts etc. Thats where this aluminum sheet came from - scavenged by me personally and saved - for someday possibly being useful for something. This sheet of aluminum was a pretty close match for the original thickness. The original PST-2000 battery tray was made form .030" aluminum and my scrap piece of aluminum was .040" thickness. Pretty darn good find and I made a replacement battery tray as close as I could reasonably make it. Im pleased with the end result.

I used a Delta scroll saw to cut out the ABS sheet after measuring the front faceplace (and tracing it) from the PST-5000. I filed the edges with a fine cut file. It is nice and straight and fits well into the PST-5000 case.

I used an unknown make/model of sheetmetal sheer to cut out the scribed lines and magic marker lines which I transferred from my paper template. This sheetmetal sheet cut nice and straight and otherwise I would have to use a bandsaw or nibbler. The sheetmetal sheer is very small and is a table mounted device with a pull-down lever - which has a shearing action. It made easy work of this project. I filed the edges and planished the edges which curled a little bit - I planished it down using a modified sawblade retoother (unknown brand or model) which I made a new die for (a long time ago) and it straightens sheetmetal beautifully.

I looked through my punch die set and I didnt have a 3/4" punch as my set of dies only goes up to 1/2". This handheld model punch I modified ( a long time ago) to be table mounted and I added a long lever to make punching sheetmetal effortless. (See my links above if you like these tools and want to make on e of your own - my CDROM plans show you how I modified it) I made the battery tray's center hole much wider than 1/2" punch diameter by nibbling out a larger diameter. The make-shift hole is decent and will easily fit the battery connectors through this hole.

I used a vintage DI-Acro finger brake press to make my bends - I did my best to compensate for the thicker metal than original. It is a slightly wider and longer and taller than the original - this is so the battery will still fit in there and not an interference fit. I made my paper template slightly larger in all directions than the original PST-2000 aluminum battery tray.

The holes where the mounting screws go - I cannot punch those because it is too close to the bend. I didnt want a sloppy bend - the holes can affect the bend quality. I will manually drill out those four holes later.

Also yesterday, I was charging up my completed PST-2000 battery pack and I tried it in both PST-2000 and PST-5000 and worked fine - the 4 hour charge was excessive because I listened to the battery pack (at 4 hours of charging) and it was fizzing like a glass of soda. This tells me that the 12V DC 1Amp wall adapter I used was WAY too much amperage. Based on my battery capacity of 2ea 12V DC 1800mAh internal - I estimate the 12V DC power adapter ideally should be around 200mA or less - which would take 5X as long to charge - but it would heat up the battery substantially less. I need to find a 12V DC power adapter  because if I continue to brute force this battery pack - the battery capacity will be diminished or the PST unit will be harmed. It just was WAY too much amperage for charging - it doesnt seem like there is internal regulation of charging amperage or current limiting. The solution is just to use a lower capacity 12v wall adapter next time.

Update 6/27/15
I made a test fit of the aluminum battery tray onto the back of the installed blank ABS rear panel - before any drilling and used magic marker/6" dial caliper to see where the holes should be. I used a center punch to make sure the drill bit didnt wander. Then I drilled only the aluminum battery tray 4ea holes.

I drilled the 4ea holes in the plastic one at a time - using the drilled battery tray to keep the drill bit on targetwhile going through the plastic panel - installing the first nut/screw and then drilling the next one and installing that nut/screw - to keep it in perfect alignment - so none of the holes are crooked or misaligned. Also I used a tapered deburring tool after the drilling to make sure the holes are neat and free of jagged edges.

It turned out pretty well - and if I didnt tell you - you would think it was made that way from the factory. I stacked the PST-5000 and PST-2000 for a side-by-side comparison. I saw a photo of a PST-5000 which was for sale on big-auction-site and was just too expensive - but that one showed a rear photo of the PST-5000 - and I used that saved photo to make my replacement rear panel similarly - I noticed the screws are farther apart - from my own PST-2000 original tray - so on my PST-5000 batrtery tray - I also made the screws wider apart. I think the reason is - the power jack is the center on the PST-5000 whereas the power jack is on the left on the PST-2000 (I havent decided where that photo was a modded one or factory stock that way because it had a 4-pin connector on the rear panel ???). I havent decided whether Im going put my own power jack in the center or top left. I still need to purchase the 3ea 3-pin connectors and the power jack and the 12V 100mA to 200mA AC adapter and also 2ea NiMH battery packs. So I have a ways to go in small purchases - but the hard part is done - the back panel and aluminum battery tray are built and it looks decent and good - its looks professional - like a factory made it. I did my best.

Update 7/1/15
I received 4 pairs of "Banana PLug to Test Hook Cable Probes" ordered from big-auction-site and came from China. I ordered 4 pairs due to needing 6 total wires for both PST units. Also a spare set was ordered for use with my Lissajous tester. The pair of cables is red/black and I plan on using all red on one unit and all black on another unit. The lissajous tester will get the red/black pair. I paid $1.82 plus $.39 shipping for each set. I pay a whole lot more when I ship something even within the same state of Illinois. It was a remarkably low price. I tested one set of clips on the PST-2000 for about 1/2 hour going through about 30 various transtors and N-channel mosfets etc. I like these clips they work well and allows for hands free holding of the parts. The PST units require the test button to be held down during the test - so grabbers or alligator clips is necessary. Here is a photo of the test leads.

Banana Plug Test Hook Grabber.JPG Banana Plug Test Hook Grabber.JPG
Size : 79.841 Kb
Type : JPG

Misc Pics PST-2000 and Misc Pics PST-2000 and
Size : 2073.68 Kb
Type : zip
consolidated_electric_pst_5000.pdf consolidated_electric_pst_5000.pdf
Size : 152.351 Kb
Type : pdf
PST-5000 Brochure.pdf PST-5000 Brochure.pdf
Size : 1080.333 Kb
Type : pdf
PST-5000 as received 101714 part PST-5000 as received 101714 part
Size : 10535.688 Kb
Type : zip
PST-5000 as received 101714 part PST-5000 as received 101714 part
Size : 9347.491 Kb
Type : zip

Caseless LC/ESR Component Tester PCB Booster Edition ver 2.2 firmware 1.02K

Purchased from big-auction-site approx end of 2012 for about $20 from China. It is a very common tester with some good features. It doesnt do in-circuit testing or thorough transistor testing. Leakage testing - it doesnt do that either. It does quick component identification including pinous of the lead order BCE EBC ... it does that very well. Even so I just dont find the information that it gives to be useful. When I check a component I compare the book specifcations to the readings of the transistor. I find that measuring leakage of a transistor is very important and this tester doesnt do that. Some newer style big-auction-site testers do measure leakage. But I have been using my BK815 for years and a cheap little tester is no comparison to a profesional arsenal of testers. Even though this less than $20 tester is well worth the money paid. It sits in a small box very little used.

I decided to post my knowledge on backlight for this 1602 LCD display. The tester is a battery hog and NOT HAVING a backlight makes your battery last a whole lot longer. But this simple LED mod which basically costs nothing - every electronics hobbyist has an LED to spare.

The short end of the LED goes on the very end of the single-inline-connector (see pics). The longer LED lead goes on the second to last hole of the single-inline-connector. This demonstrates a 1602 backlight or non-backlight version and which pins (the last 2) are for the backlight. For non-backlight LCD - these 2 pins are missing. A simple backlight is putting a standard LED on the side of the LCD module held in place with a dab of epoxy or silicone caulk. Thats my "CHEAP Backlight Mod" for your Cheap $20 component tester. Otherwise just use a 1602 backlighht edition LCD module and plug it in. It will work just fine but the battery will drain quicker.

This tester uses a standard 9v battery. I normally use a rechargeable battery for everything and these have less than 9V just because it is rechargeable and they produce less voltage than standard batteries do. The tester works with a battery of 6.9volts or higher. 6.9 volts is the bare minimum battery power required.

The side of the LCD module has pairs of empty copper islands - this is where the LEDs go and they face inwards towards the LCD side to light it up. Of course with the 2 missing pins - no power would reach those LEDs - so the user would have to provide those missing pins. The LED lit up shows where the power for the LED or multiple LEDs comes from the last 2 holes on the single-inline-connector. So really this LCD module can handle 4ea LEDs (2ea on both sides of the LCD)

I dont plan on modding my own tester. Like I said the tester is a battery hog and adding LEDs just shortens the battery life even further. Its fine just the way it is. Good enough for occasional use - identifying some oddball transistor or seminconductor that I cant find in any book and knowing the pinout. At least it tells me what the part is and does a quick check - most of the time that is good enough to determine if the part is "probably a good part" 

A unknown three legged part will not be identified or will be identified as a resistor or some other oddball display. In that case I know it is a bad part. Its a darn shame if at that point I couldnt find it in any of my books and I had to rely on the tester to identify it. If it cant identify it or gives an obviously wrong identification (3 legged part only sensing at 2 pins etc) - its probably blown/bad part. Its a very rare thing for this tester not to be able to automatically identify a part - even in a rudimentary way - at least it tells you what the part is - useful for small low power semiconductors.

To a complete novice - the information provided for semiconductors inserted seems "WOW look at all of that infromation" but truly almost none of that information is useful. It doesnt give the specifications of the part which are useful for determining if the part is weak or blown or defective. It often doesnt correlate to the book specifications. It gives the novice the impression that the data is the part specifications- no it isnt. Its not all that useful. But it can be used when no book specifications are available and a quick ridiculous novice check is all you can do to an unknown part. If it is blown - the display will mis-identfy the part as something quite obviously wrong such as a resistor or capacitor - when in fact it is a three legged part- because something inside the component is shorted or crossed or weak or damaged in some way. This tester is good for that sort of thing - as a last resort for figuring out oddball parts/confirming potentially blown parts. (See the picture which shows a transistor 2N 3906 being tested - but it is seeing it as a diode - which it is not. This is a transistor misidentified as something else - so that means it is a blown bad transistor - simulated FAIL by only inserting 2 pins of the transistor)

At this time I do not have a 3d Printer - when I do I will make a case for it. Right now I cant justify the cost of a 3d Printer - maybe I will build one or buy one when prices come down or I find a used one. I have a laser engraver but I feel like cases are better made by a 3d Printer. Laser engravers are great for engraving the decorative front panel. Use the right tool for the job.

Photos show my "LED - Cheap Backlight Mod" for cheap $20 semiconductor component tester.

Photos show 2N 3906 transistor test- FAIL

LED is not inserted this way for testing purpose. LED lights up when LCD lights up. LED shuts off when LCD shuts off.

Update 010418
I have used CAD software "Solvespace version 2.3~7c1ca460" and have modeled the Caseless Component/ESR/LCR Tester electronics. I have modeled it in detail including the switch and chip LED and also the position for a larger LED. The screw holes for mounting the LCD and the screw holes for the 2ea Boards have been modeled with a dial caliper. This electronics modeling took me an entire evening and throoughout the night and Im writing this at 8am - so the basic PCB and electronics took 3/4 of a full day to do. Since I have last updated, I have completed my 3D printers heated bed and tweaks to improve the precision of printing to where Im satisfied/amazed. I feel that this long unfinished project will soon have an enclosure - in a very professional manner. I plan on using my model of the electronics to sculpt the case around it - and then delete the electronics - leaving only the case - that way it will be a nice fit - and can make contours or custom shape as I wish.

As I looked online for CAD/CAM software - I found no other modeling software actually worked on my older XP laptop or required major add-ons etc to make it work (I downloaded several others first unsuccessfully). I found this free software and required nothing in further installs or add-ons. The CAD software was very well behaved and was a positive experience. The online Youtube demo videos on how to use Solvespace were helpful.

Since my 3d printer is small with a 100cmx100cm printbed - I plan on making a square-style rather than long-style case - as the battery compartment placement on the side versus the bottom or top would affect the case dimensions. I have experimented with ABS and feel confident in my 3d Printer being able to make this case.

Here is a screenshot of my CAD work on the PCB/LCD assembly & CAD file I created for the electronics assembly- for the purpose of making a 3d printed case for it.

Update 1/6/18
I have worked for a long time on creating the CAD file for the case and have run into "phantom issues" with open source CAD software- chasing errors which are in the form of "redundant" constraints and having to make sure ONE and ONLY ONE constraint is a very frustrating way to use software. Sometimes scrapping a version simply because an error/bug cropped in there even though running tests on it show no errors. Nonetheless - this process is helping to make the shape and make decisions on where walls/shell parts etc for the case should go and keeping things straight and basic looking to reduce complexity that the software has trouble with.

Here is an almost fully enclosed shell (rear wall is not a wall but a battery compartment separator) full of red areas where the software is warning about trapped parts- but I plan on deleting the electronics after case is completed. In the meantime the red lines are an obstruction in viewing/creating. Decisions on where to split the case is not made yet.

Update 3/4/18
I have figured out how to solve the redlines in Solvespace for my drawing. I needed to add a checkmark on "layer" G023- extrude "Force NURBS ... triangles" which removes the redlines. These redlines were thick and heavy and I couldnt See the drawing to continue. Adding this checkmark somehow tells the drawing "Its OK to have back-to-back adjacent parts" that is the best answer I can give. There is no error and most of the time the software works fine without this. But every once in a while in my drawings - I have to figure out which "layer" needs that checkmark. I dunno - its just something to do with Solvespace- who knows? Its a good free software- what do you expect for free? Its good enough and works fine. I have added a screenshot of the checkmark added to make it work.

I own several versions of Willem Eprom / ROM/ Prom/ EEprom / Flash / PIC Programmers ranging from early DIY etched board to the above online-purchased advanced model. Pictured above is a PCB50 which is a digitally selected (no dip switches) pushbutton selected model. I can select the voltage and other paraameters with pushbuttons. The LED bargraph lights up according to my settings. It is exactly like the earlier models of DIY Willem and has the same functionality of my other boards - but I like the digital selection and use it/prefer it 100% over my other Willem programmers. This is a parallel port version which uses the parallel cable to communicate with a PC. I use a dedicated older PC for this Willem programmer. It is powered by the USB cable but the USB only supplies power to it. I have used this WIlem to flash/reflash BIOS and update ROMS and burn chips for use in projects. The Willem programmers are very useful - their only drawback is lack of thorough documentation. So I had to figure out each and every chip setting manually - for all chips I have ever burned. You would think that an online source for these settings would exist - but really and truly there is no source for this list.

I have an interest in compiling this list of settings as I have figured out quite a chip few settings on my own and I keep a detailed notebook on what settings worked for me for each chip model I have burned. I use Willem Pro software version 0.99kb for PCB5.5c running an older pc dedicated for chip burning which runs WinME and has both a USB and parallel port and 1GHZ processor which is sufficiently fast enough for high quality burns.

I have successfully figured out the settings for the following chips using Willem, and I have made notes for the following:


SST 49LF040B

SST 49LF004B

SST 49LF002A

Winbond W39080APZ

Winbond W39V040BPZ



Winbond W49V002AP

Winbond W39V040FCPZ


ASD AF49FZ008-12 0018

2764 older UV erased chip

Texas Instruments TMS 2732 older UV erased chip
                                                    (Interestingly the 2732 and 2764 uses substantially different
                                                    settings on the WIllem 5.5C programmer - I started out
                                                    trying to use similar settings without success)

If you need the above settings - contact me to purchase these Willem settings for a few dollars each payable by paypal for the DIYer. Also available is custom re-flashing the file onto a chip that you provide. I can read existing chips, erase chips, and reflash old chips and burn new chips. Some people like to send me their chip. Some people like to do it themselves- but do not know how. I charge a small fee. If have a chip that you want settings for or custom programming - let me know, and I will quote a fee. Sorry I cant program MAME roms for you due to copyright.

Global Specialties LM-2A Logic Monitor for CMOS or TTL ICs

This device is basically a "Logic Probe" It comes standard with a 16-pin ribbon cable and attaches to the top of the tester with an IDC connector. The IC Clip end is a 16-pin Dual In Line ( DIL ) which can attach to many chips 16-pin or shorter. For much smaller chips and or narrower chips a self-made adapter is necessary. Imagine 16ea logic probes attached to an IC alligator clip - that is what this device is. One LED connects to each and every pin on the IC. The LED is either Full On/Medium On/ Off/blinks to show the logic state of that particular pin on the IC (also half bright means there is a waveform present). Of course the main purpose of this is to monitor a live circuit while it is under power and operating.

Sometimes a chip will have a bad pin and the rest of the IC operates. This bad pin will stand out as being in a different state when compared to previously tested boards of the same type (in reference to my notebook notes from previously tested boards) So it is important to keep a record of boards I test regularly and compare them with drawings or sketches or descriptions that I have observed.

Also this is useful for comparing 2 boards side-by-side (one known working board and one non-working board)

For example a board previously tested may say in my notebook, "IC XXXXX ... pin 6 ON" but when I test another board - I may actually observe that pin 6 is actually LED off. Then that makes me suspect that this chip has an issue (When one chip has an issue - this also affects other related ICs LED status too). Many boards have a boot-up logic state - as soon as that board is powered on - certain LEDs light. If something is not right about the light up or off sequence - it is observable with this tester. I tend to use this tester by clipping over the IC and then powering up the board under test - that way there is a predictable initial viewing of logic state of that IC in my notebook. Sometimes I will elaborate in my notes about what the chip looks like after bootup is complete or in various modes.

I like a Logic monitor (rather than a logic probe) because it is safer for the circuits and ICs - due to cliping an IC Clip over the chip - rather than probing around with a 1-pin logic probe. The IC Clip is locked in place and can be attached with the power off. So there is absolutely no reason to ever short 2 adjacent pins on an IC (by probing with a Logic Probe for example).

If the LEDs flash/ON/OFF state according to my notes (from previously tested boards) - that chip is probabably not the issue with the board or a more in-depth testing is needed on a different tester.

The IDC connector lends itself to changing out to a homemade IC Clip of any style (DIL, DIP, SOIC, etc) and there are a tremendous amount of IC chip pins and styles including surface mount that I make custom attachments/ribbon cables for my own use as I need them.  Big-Auction-Site is a good source for used or new IC Clips.

One of the main purposes of this device is to see if a chip is dead or pins are dead or stuck on or stuck off. Another main purpose is to determine how much voltage a chip is rated. The variable control allows viewing the brightness of the LEDS. It is a good idea to run this device - BEFORE using an In-circuit IC tester as some boards run chips well beyond 5V. If the board is supplying more than 5v - then an in-circuit IC tester should not be used - otherwise the IC tester will be blown or damaged due to higher than 5V . Purch 9/14 approx. Mfg Date unknown estimated 1985

Sometimes Global Specialties is written as "Continental Specialties" as it apears they had a business name change. The LM-3 which I am looking for may be "Continental Specialties" or "Global Specialties" either one.

I am also looking for the manual for LM-2A as I do not have this manual.

Note I also purchased a Global Specialties LM-4A 40-pin Logic Monitor from big-auction-site 8/14 but it arrived with a severely damaged LCD display which looks proprietary. If the reader has a replacement - LCD screen for it let me know. My 16-pin logic monitor uses LEDs which is more rugged. I suspect the previous owner left this LM-4 someplace where it froze and internally cracked the LCD. I dont believe it was damaged during shipping. The seller was responsive and immediately refunded without requiring return. I included a downloadable picture so can see the LCD is bleeding black liquid crystal fluid internally (actually LCD liquid is clear but the polarizing filter makes it apear black). A working LCD would have no black showing. I am still looking for a LM-4 or LM-3 made by Global Specialties as these are 40-pin capable. Ideally I'm hoping to find an any condition LM-4 with a good LCD which I can use for parts. Let me know if you have one for sale.

Global Specialties LM-2A Box.JPG Global Specialties LM-2A Box.JPG
Size : 53.858 Kb
Type : JPG
Global SPecialties LM-4.JPG Global SPecialties LM-4.JPG
Size : 116.405 Kb
Type : JPG
Global Speciaties Logic Monitor LM-3 Global Speciaties Logic Monitor LM-3
Size : 1752.838 Kb
Type : zip


Radio Shack Probescope Backside.JPG Radio Shack Probescope Backside.JPG
Size : 123.053 Kb
Type : JPG
Radio Shack Probescope & Wires etc.JPG Radio Shack Probescope & Wires etc.JPG
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Type : JPG
Radio Shack Probescope

I purchased this item from my local Radio Shack store in the mid 1990s. It is a portable pocket pen-style oscilloscope 5MHZ and maximum 100V measurement. I use it primarily as a logic probe as it shows TTL and Analog HIgh and Low and also live waveform.

I purchasd this brand new and at the time of purchase I barely had the funds to buy it, and I pressured myself to buy it because it was soon to be discontinued at the time. An optional accessory for it was a battery pack which clipped to the rear of the unit. I have never seen this optional accessory or any photos of it. If I had the funds - I would have special ordered it as it was not an in-store accessory. This tester runs on a 9V standard rectangle battery and has a backlight LCD.

I have read that some online people blew out their Probescope by connecting over 100V to it. The book clearly states (also says on the backside of the unit) that it is for up to 100V Maximum - do not attempt to measure your power line with it. DO not accidently connect it to power supplies etc. I suggest only using it for analog / TTL low power testing - using it as a high-end fancy Logic Probe.

It has a graphic pixel display which shows live moving waveforms and also gives a numeric display for voltages. The buttons are momentary and used to toggle between modes

I loaded the software diskette that was included - on my Toshiba 1910 B&W laptop with Windows 3.1 (laptop purchased new in early 1996) and is useful for making snapshots or printouts of the waveform. It includes a cable to connect the Probescope to the 9-pin RS232 port. I have this old perfect condition laptop for running old software and printout is to a Panasonic KXP-4420 B&W 300dpi laserprinter or Canon BJC-70 300dpi inkjet color printer or screen capture imported to Adobe Photoshop or Aldus Photostyler - from there I can export it to my modern computer and color laserprinter Samsung CLP-300 600dpi.

This pen style oscilloscope has no X-Y mode and cannot be used with my Lissajous pattern tester - because that requires an oscilloscope with XY mode for drawing. I noticed that there are a few modern mini-oscilloscopes on big-auction site - but even those lack an X-Y mode. X-Y mode is very important to component testing add-ons which this Probescope cannot attach to. A worthwhile homemade attachment is a 1x or 10x probe - I have never made one/modified one because I purchased a full size used oscilloscope Kikusui a short time later after purchasing this pen-style unit.

If the reader has a "special order" 9v battery pack available for sale - I would like to buy it. When I someday buy or build a 3d-printer - a worthwhile project is a clip-on battery pack for it. I have never seen one - no pictures of it were posted in the Radio Shack catalog.

Note there is a "Sister" unit made by "OziFox" approx the same era and was virtually identical except internally there were some minor differences between these two brands. The main difference is a much wider 2x "rectangle" display on the Ozifox as the Probescope has a small "Square" 1/2 wide display. Otherwise they look nearly identical.

Here is a youtube video (not my video) showing Ozifox unit display

Update 4/24/17
I emailed the mfg and inquired about the availability of a Radio Shack special order battery pack for Probescope which I bought brand new in approx 1990. The response I got is that he will check with someone and get back to me. I never got a response (about a month and a half ago) and no reply to several attempts afterwards. I had inquired about obtaining a photo of this battery pack, any parts or pieces, or to buy the battery pack in any condition. I didnt receive any information or photo or anything. I got a reply but that reply supplied me with nothing.

Can anyone provide any information about this special order battery pack? Anyone ever order one? Any photos of it? Any still in existence? Any insights would be appreciated.

Did the battery pack attach to the Probescope as a clip-on or was the whole case replaced and battery inside longer or wider case? Was it rechargeable or run on standard 9V or AA or AAA batteries? Was it just a module "brick" with a cable that plugged into the back of probescope. I have no idea what it looked like. I know of no-one else who ordered this battery pack. Let me know.

Odd looking Capacitors with Color Stripes

Sometimes I run into strange looking parts as Im repairing older devices. For example, while fixing a 2200watt Gasoline powered Generator Alternator from the 1970s - I rebuilt the foam sealed aluminum encased Generac Electronic Control Module (new one is unobtainium- so I decided to rebuild it) and saw 2ea rainbow colored disc "capacitors" which I saw were broken/busted due to vibration (and possibly from prying off and coaxing off all of the foam it was encased in). My BK Precision meter showed them as capacitors - as I tested the caps with one missing leg - still worked but needed replace. On big-auction-site there are some sellers who have photos of these vintage capacitors with various color stripes which denote the capacitor values. Some guitar mfgs and amplifier mfgs etc used them and some repair techs feel they are better for certain applications - such as music studio reproduction and musical instruments etc.

I am including here a photo of one capacitor and a summary of what the color band / stripes mean. Generally these are considered Polyester Metal Film capacitors and the "Tropical Fish" capacitors inside my vintage Craftsman generator were quite brittle and were replaced due to cracked busted outer shell and dangling leg. Replaced with standard polyester film capacitor of same specification (if it were a musical application it would be better to replace with a tropical fish capacitor to avoid sound reproduction accuracy gripes/complaints. For a generator - a standard modern epoxy encased capacitor is fine and would better withstand the engine vibration - in my professional opinion. The old one lasted 40 years (bought it used- who knows how many owners) which is not too shabby. If I didnt rebuild the electronics board - then this old generator would probably go into a landfill or recycled. It works fine now.

Color Code

Tolerance Color Code

Voltage Color Code

Color Stripe Meaning
Cap color is Digit1
Upper Stripe is Digit2
Next stripe down is # of zeros
Stripe just above base is Tolerance
Base color is

"Tropical Fish" (a slang electronics technician word) vintage Bullard capacitors are generally but not always picofarad pF small value caps.

My Test Notes on ODD parts

Blue non-directional Diode TIP DB3 is used along with TRIAC When testing a blown DB3 showed as 26pf to 28pf on caseless component tester. And when I bought a replacement exact match - the brand new one showed as "no component or unknown component." very easy to mistake a good part as being "open/blown" In this case I changed it out with the new one.


Vacuum Tube Testablility For U-Test-M Tube Tester

I am making a list of testable tubes here. This list is not necessarily about cross referencing. This list is about what settings to use for the U-Test-M Tube tester - as there are more tubes in existence than are listed on its rolling chart. So this Testability tube list will allow me to take unlisted tubes and know which "known tube" it is tested the same as on the U-Test-M roll chart.

I hope I explained that clear enough - this is not a substitution chart for you to swap tubes in your TV set or Radio. This is a chart which expands the capabilities of the U-Test-M tester. I need to look up your tube on my list and then find an underlined tube heading - then use that "subtitute tube number" to look up the setting in the roll chart. It is an in-direct method of expanding by many times the capabilties of the U-Test-M.

The U-Test-M is regarded as the pickiest of all of the testers- people regular folks who repair their own TVs and Repairmen often say - "when I test that tube on my Hickock it passes just fine - but on the U-test-M - it fails it. That XXXX drugstore/tv repair shop just want to cash in on selling tubes. Dang-nabbit (or worse)" Well I look at it this way - The U-Test-M is for people who want to restore a tv or radio to top notch condition - rather than "good enough". Still it doesnt test Mutual Conductace - so really having more than one tube tester is a good idea. I plan on owning a HIckock and a U-Test-M - Both (I dont own any tube tester at this time). There isnt any reason why a shop should only have one tester. If the tube passes all the tests from every tester - then that tube is very good. If the tube is very good - it should be able to pass even the U-Test-M. I'm still looking for a U-Test-M model 2500 I havent purchased one yet- they are usually sold by sellers several states away and I'm hoping to find one that is within driving distance. Let me know if you have one for sale.

With tube based electronics - the weakest point is not the tube - it is the paper and wax capacitors - that is the souce of most problems. The tube is easy enough to se if the filament is glowing or not. Just becaus the filament is glowing - doesnt mean the tube is good. With the invention of the ESR meter - testing those old caps/replacing a few bad ones is a breaze and usually enough to get an old set up and running. But the U-Test-M made testing tubes easy enough for the Do-It-Yourselfer and I remember a local Zayre store (you dont hear that store name too often anymore) had a U-Test-M model 2500 at the front of the department store just in front of the cash registors and to the right of the Service desk. I can remember testing tubes at the Zayre store (as a customer using the stores self-serve vacuum tube testing machine in the middle 1970s approx) The Zayre store was a department store like Kmart, Target, Walmart, Venture etc.

It will take quite a while to make this list and may contain errors so use this on an at-your-own-risk basis - as I will do my best. I am using a multi-column feature and this is something that is new for me when building my webpage - under construction - your patience is appreciated. This section Commenced 1/25/14


01A  12A, 112A

0A3  0A3A, VR75

0A3A  0A3, VR75

0B3 OB3A, VR90

0C3 0C3A, VR105

0C3A 0C3, VR105

0D3 0D3A, VR150

0D3A 0D3, VR150

0Y4 0Y4G

0Y4G 0Y4

0Z4 0Z4A

0Z4A 0Z4, 0Z4G

0Z4G 0Z4, 0Z4A

1A4 1A4P, 1A4T, 1B4, 1B4G, 1B4P, 1B4T, 951, 32, 34, 1C4, 1K4

1A4P 1A4, 1A4T, 1B4P, 1B4T, 951, 32, 34, 1C4, 1K4

1A4T 1A4, 1A4P, 1B4, 1B4G, 1B4P, 1B4T, 951, 32, 34, 1C4, 1K4

1A5G 1A5GT, 1A5GT/G, 1T5GT

1A5GT 1A5G, 1A5GT/G, 1T5GT

1A6 1C6

1A7G 1A7GT, 1B7G, GT , 1A7GT/G, 1B7GT/G

1A7GT 1A7G, 1B7G, GT , 1A7GT/G, 1B7GT/G

1A7GT/G 1A7G, GT, 1B7G, 1B7GT, 1B7GT/G

1AB6 1AC6




Alunar HB-R100 3D Printer

I purchased this used from big-auction-site in very good physical condition with original box September 2016.100mm x 100mm x 100mm build volume. Standard Non-heated bed for PLA only.  1.75mm filament. I see that the mainboard is Chitu - so I decided to upgrade it to heated bed and ABS capable. I like the 2.8" color touchscreen display and the sturdy thick steel construction. The standard use of a common reprap nozzle/heated tip system, spool feed system, ALL 5ea standard identical Nema 17 stepping motors makes repair and upgrades possible with common reprap components.

The purchase of this 3-D printer is driven by my need to make cases/parts for several testers- which the vendors sell without a case.

I ordered a WIFI module and Heated Bed module as Add-ons for Chitu mainboard. I ordered a standard 360watt 12V power supply typical for DIY 3d printers (I spent a whole day fixing this $20 brand new aftermarket power supply- unsoldered torroid transformer, straightened bent heatsink, retap threaded holes, bent aluminum case, etc). The standard power supply which came with the Alunar HB-R100 is not powerful enough to drive a heated bed- hence the need for the add-on module and add-on power supply.

***********The following paragraph has INCORRECT conclusion about cause/solution***********************

I was lucky that the original SD card was included with my 3d printer (I store this SD card for safe keeping) as I reloaded the original firmware which restored correct operation (when I initially got it - the homing function was "crazy" and sent random axis in the wrong direction and BRRRBRRR stepping motors not finding their endstops) Firmware install - found on SD card - solved those issues. (firmware update didnt solve - see next paragraph)
Update 11/27/16
I am adding this tidbit of information as in retrospect- The entire previous paragraph insights about crazy BRRR homing function was incorrect or partially incorrect?. See Just yesterday I installed the MOS module/standoffs/drilled 4 holes in the case. After doing this modification - with no electrical connections - just mounting work - I put it all back together to make sure nothing was broken and screen uncracked. Well I got the not-homing-correctly (but no BrrrBrr noises) - very similar to when I originally got the machine from big-auction-seller. So I though about - whats going on here? Well the only thing that I did really is I moved a zip-tied bundle of wires out of the way. So I figured - well maybe some connector is unseated or a wire internally is busted or making a bad connection. So I took the bottom off and moved that zip-tied set of wires to where it was before and also pushed down on all of the connectors to make sure it was seated correctly. When I reassembled - homing function worked just fine. So in retrospect, maybe it wasnt a firmware issue - but instead was some bad connection which I reseated to make proper connection.

This 3d printer is very similar Looking to MonoPrice Select Mini / Malyan M200 but not the same at all (steel case is different (side of case has panels held w/ screws versus welded all sides case, z-axis stepping motor (all 5 stepping motors are identical nema 17 style on Alunar) LCD Touchscreen, Chitu controller, non-heated bed platform standard- but upgradable) The Monoprice and Malyan use a rotary knob selector and non-touchscreen color. Different controller and firmware. The X-Axis and overall apearance looks identical to Alunar & Infitary ??????

Sister model - which look very similar and may be exactly alike? Infitary HB-R100 (alibaba auction site)

My Installed Upgrades DIY
(360watt PS, Chitu WIFI Module, Chitu Heated Bed PCB, Firmware from SD card, Heated Bed MK2B (special size 120mm  x 120mm)
Cura software 15.04.6 runs on a Win XP SP2 laptop Dell 3650

Equipment which I need a case/other parts for
1. Electronic Component Tester (Transistor Tester/LCR/ESR) case
2. Willem Programmer case (I have several version boards)
3. Caseless IC Tester case (numeric keypad style)
4. Caseless IC Tester
case (row of keys style)
5. Power Button/head for BoardWalker 103 to fit power switch shaft
6. Side Cover for BK 560 IC tester (combination of 3d printed parts and ABS textured sheet cutouts)
7. 9V Battery Pack Add-on Attachment for RS Probescope

Update 1/21/17
8. Switch hole cover for GJ8018LCD Hot Air solder/desolder tool - done

The main purpose for this 3-d Printer is to make the above cases/parts.
I want to use ABS (ABS Styrene) rather than PLA as PLA is organic. I want to make parts from ABS filament and my initial tests with ABS curling in random layers during the print leads me to believe that a heated bed is necessary. I was able to get ABS to bond to a 1/16" textured ABS black sheet without hotbed but subsequent layers randomly didnt stick well to the underlying layer- in thin walled or thin sections. A test cube shows warped bottom but the rest printed fine. For my needs in printing ABS to make replacement parts / cases / cover etc ABS is my choice for a professional project completion.

My initial test with this 3d printer was astonishment - the very fine detail and exact placement of one layer over the next layer. Capable of "Layers Almost As fine as a record groove." Also I find that Cura software reads my 3-d Scanner DXF/STL files from my 2ea RolandDG Picza scanners (which lightly contact an objects surface with a needle tip)

After firmware install - all functions work properly -
without any more BRRRbbbRRRRR or wrong direction axis movement. Bed leveling procedure works well. Nozzle touches the bed off-to-the-side momentarily to remove "snot" or dripping before beginning a print. The extruder nozzle makes a circumference path just outside the part- during this circumference pass - the filament line attempts to cling to the printbed and is eventually successful - either right away or at some point around the circumference path.

I find that smooshing down the initial layer onto the ABS homemade sheet really attaches very well onto a non-heated standard bed (by having a level bed and leaving only a 1 piece of paper gap between printhead nozzle and bed while leveling). BUT subsequent layers 4-5-6+ layers up there is a pealing or curling up - so the homemade ABS buildplate I made only helps the initial layer - the heatbed heat is required to continue to heat previous layers. Otherwise it will curl up - similar to the way a bi-metal spring inside a conventional thermostat for a home furnace works.

Cura Software Printout Specifications
.1mm Layer height, 230deg C extrude Temp (for $10 ABS Black Filament) , Speed 30 to 40, 1st layer speed 20, Last layer speed 20. Downloaded from the Cura website and this version works with Windows XP SP2 just fine.

I save the g_code file to a standard 2GB SD card and then take the card to the 3d printer and run the 3d printer standalone- without a laptop attached. The laptop is used to run Cura to import drawing file (.STL) then save as G-Code onto the SD card. While the 3d printer is making the part - the settings such as speed and temp can be tweaked from within the Alunar LCD screen.

Heated Bed Notes
I contacted MonoPrice by email and received a reply that "Unfortunately we do not have any replacement heated bed available for sale at this time" 9/28/16

I contacted Malyan by email and received no reply regarding buying a heated bed from them. 9/27/16

I considered using a heated bed option for Fabrikator Mini which measures 120mm x 120mm - some of these add-on boards have 15W or 60W connectors for low power or higher power. In the end I decided to use a different one because the way the predrilled holes placement.

The MK2B special size 120mm x 120mm holes placement lends itself to "hug around" the existing aluminum plate on my Alunar HB-R100 using DIY metal plate clips or bands

Update 10/16/16 I emailed big-auction-site seller of my MK2B Heated Bed - question - to find out screw thread size. Answer M3

Update 10/22/16
I positioned the heated bed MK2B 120mm x 120mm such that the printhead can reach all areas of the heated bed. Then I used a magic marker to mark the 4 points where the heated bed's threaded screws touch the existing aluminum bed. I used a Dremel model 395 with a brown cutting disc to eat away the edge at those 4 marked points. I carefully used the Dremel tool to make a clean C shaped notch and cleaned up my work even smooyther with a 1/8" diamond encrusted bit. The result is 4 smoothly cut C shaped notches. The heated bed is able to mate up with the existing aluminum bed - just a tad above it. I ordered 8ea (4 extra ones not needed) for about $3 M3 Knurled Thumb Nut so I can secure the heated bed. I am awaitng the arrival for these nuts. The rest of the items have arrived - some from USA and some from international. I have included a photo of these mini M3 thread thumb nuts and my DIY notched modded aluminum plate.

It is important to note that any type of pressure will BEND the aluminum plate - so no drilling or using a punch!!!! I Carefully clamped the aluminum plate in a small vise with cardboard to protect the finish. I clamped the aluminum plate vertically and used my marker marks as a guide and made test fits with the heated bed to check my progress. I was careful never to put force on it and I believe it is nice an straight.

The notches are beyond the extruder tip reach and the notches will never interfere with any non-heated bed print. I have included a photo of the notches and heated printbed add-on modification.

As a result of the add-ed heated bed mod- I had to readjust the Z-axis switch thumbscrews so the print nozzle is just above the heated build plate rather than the now-notched aluminum plate. I found that there was enough built-in adjustability of the z-axis thumbscrews to accomplish this.

I have installed the WIFI module and can connect to it using an Android TV box but I lack the app to control it. I see the Alunar's LCD screen shows and WIFI checkmarked. I still need to figure out how this works. I feel that the WIFI module is working properly and is installed properly. I see an online page which shows an app for Apple phone but I dont own that brand at this time. I may need to acquire an Apple brand tablet or phone in order to use the WIFI control app.

Update 10/24/16
I was able to connect and use my WIFI add-on module. While I searched on the Chitu website a week ago , I downloaded all of the files and folders related to my mainboard, power module, wifi module etc. I have been reading and studying the PDF files and trying to figure it out. I previously had an unsuccessful attempt to load the software ChiTo Pro last week. But today I decided to try it again. It worked fine today and after installation I received no error. I disconnected from my internet WIFI connection. Then I connected to the Chitu WIFI module which shows up as "3d Printer" WIFI signal with 5 bars of power since it is so close. I have been trying to figure out how to connect and what seems to work is double clicking on the picture of the green chain in upper left portion of Chitu pro screen.

Here is the download link to Chitu Pro Software (works on my older laptop with XP)

The odd thing is that I tried to install it last week and after installation gave me an error. The ONLY thing I did with my laptop since last week is - I tried to install Microsoft Net Framework on it where some other software required it? That may have added some file to my system that it didnt have before?

I am able to see the content of my SD card, home works, some commands I tried and my 3d printer moves. Right now I dont know the Gcodes but from my experiments (very carefully) seems to work. I tried to disconnect/reconnect/close program/rerun program and seems to be repeatable. Although sometimes screen is mostly English and other time has international language characters. But that is very minor - I can still figure it out regardless of language characters.

Im so glad the WIFI works now. I need to calibrate my 3d Printer and having access to those commands is now possible.

I figured out how to change ChiTU Pro software to English - in upper right hand corner there is a question mark symbol - just to the left of that is a graphic symbol - clicking on the graphic symbol will toggle between languages (required restart of Chitu Pro)

I issued some command M503 (to list current settings in the 3D Printer) doesnt work but responds "OK"

From what I was able to read about most 3d printers - this should have listed all of the internal settings - but didnt work for me.

In Cura I can scale an object so what I need to do to size the object correctly is scale up a certain percentage to get it to be the right size. Right now my "steps per mm" is probably wrong and I dont know how to list the internal settings or change them. So scaling the object in Cura is the present solution. I was hoping to use Gcodes and Mcodes to fix this.

After my succes on my PC laptop, I tried again on my Android TV and was able to get the APK file downloaded to a flashdrive using a PC and then installed on the Android TV using the built-in "App Installer" then loading the Chitu app file from my flashdrive.

Here is the link for Android version of Chitu controller which worked for my TV and probably any Android Device.

I can say that it is a much more basic control than the Pro version but I tested it to home and move and seems to respond like it should. Im glad Android is now working as a backup to my PC- just in case my older laptop fails.

Update 10/28/16
I switched the wires around at the connector of the MK2B special size 120cm heated bed.
-Heat = Black
The above colors seem to make more sense than the random colors as received. I used a watchmakers screwdriver flat to press the clip-in portion of the connector and then just remove the wire with crimp end and re-insert where it should go.

I have determined that this heated bed does come with a thermister as I put my finger on the very center SMD component (the one closest to the center hole) and resistance changed with my body temperature. I also compared the reading of the SMD component to a pack of 10ea replacement thermistors I purchased on big-auction-site. The resistance value is within a decimal point in ohms (. I did notice that the SMD part takes a few seconds to get to its resistance value. Versus the 2-pin component responds instantly. They may work equally - but my opinion is the 2-pin version is better and faster response.

Unmounted "3950 Thermistor" Readings with a multimeter
(Room Temp resistance = 113k ohm approx       My Finger Resting on it resistance = 83k ohm approx)
I get very similar results with SMD chip thermister and 2-pin component thermistor.

I have determined that SIG (I changed it to a white wire) and GND (I changed it to a black wire) are the 2 that need to be connected to a 2-pin female connector. I ordered a few online today in the form of a cable 20cm length - with same connectors on each end. The connector is called "XH2.54" on big-auction-site and on aliexpress it is called "XH connector 2.5mm" and is the same connector that was included by the mfg as part of the Chitu Mosfet board. So I just ordered a few more as I want to do a nice neat clean job.

I also ordered a green power connector from "HT5.08 2pin Terminal plug type 300v 10A 5.08mm pitch connector pcb screw" which mates with the Chitu onboard socket. It is a right angle connector - not a straight one.

I am awaiting some parts to arrive from International. Some have arrived and may be anywhere from a week to a month. I like this 3d printer and to me it is worth the money to upgrade it to heated bed and wireless.

Update 10/29/16
I went to the local dollar store called "Dollar Tree" and was looking for cell phone glass screen protector - but only found plastic ones there. I found a white 5ft length Wiring Cover which is for my heat bed cables. This is sometimes call "wire loom" in automotive stores. I have never seen a whte one before and price was $1 is a good match for 3d Printer color. Resembles a mini vacuum cleaner hose with a slit down the entire length so you can stuff wires in there for neatness and less wire damage that way.

Update 11/9/16
I have received the thumb nuts M3 and they are a perfect fit with sufficient clearance where it doesnt hit the Y-Axis home switch circuit board solder joints. I was very glad it threaded perfectly into the screws on the Mendel 120cmx120cm special size MK2B Heated Bed -which secures it to my modified existing aluminum bed.

Update 11/13/16
I received the wires and connectors and I received the wrong size - it doesnt fit, but the wire color is exactly the same as the originals on Alunar 3d Printer. The XH 254 connector is too small and pins too close together and doesnt fit the Chitu socket. I will have to try again.

Update 11/14/16
I received a reply from kind seller on big-auction-site regarding Chitu MOS PCB module - the reply received was HX2.54 connector - which I believe is a Typographical error. I have proceeded to purchase XH2.54 connctors from 2 vendors on big auction site- one vendor with just the connector and a different vendor with connector with red/black wires already attached to connector. After I receive - I can just attach the bare connector to the other end of the premade-connector-with-wire in order to make a double ended cable.

I have concluded that the white wire double ended premade wire is being sold on big-auction-site as a BOGUS and is not actually XH2.54 at all. I have included the vendor reply and photos of my connectors 2nd try purchases below.

The correct connector has red/black wires and is sometimes called "XH2.54 Power connector" and the ones with white wires are too small and wont fit the Chitu PCBs. I believe the XH2.54 Power connectors are common Radio Control items and probably could be purchased from a R/C Radio Control hobby shop - but much more expensive there per piece. I prefer to mail order from international as I get a greater quantity for a few bucks. Then I have some extras for future projects.

I could also cut off the connectors on the white wire sets and just crimp on the right connects (when they arrive) to make a color matched to original wiring. Im most likely going to do that as a I have a professional hand crimper which will attach the terminals to the wire end.

Update 11/26/16
A couple of days ago I received the XH2.54 connectors with attached red/black wires and also the green HT5.08 terminal connectors.

I wrote 2ea scripts for the heatbed (created in Windows Notepad and saved as a standard non-fancy *.txt file). This updates the built-in firmware settings. "Enable Heatbed Parameters..." turns on the mainboard settings to run a heated bed. If a heatbed is NOT connected - then instead use the "Disable Heatbed Parameters..."  I just figured this out and ran it on my own Alunar HB-R100 and seems to run in the menu- as I can now access temp settings which before were disabled as factory stock.

The rest of the firmware paramenters are left alone. The script only modifies the heatbed settings. I have included the 2ea scripts here.

How to load and run the script
1. Load the files onto SD card
2. Use Alunar HB-R100 touch screen to go to "Print"
3. Select the file from the SD Card
4. Print the script file- when complete - it will show that screen has been run.

Another thing I did is drill 4ea holes in the back of my steel case and used 4ea metal standoffs with screws purchased from RadioShack Cat#276-195 which I had in inventory for years. Glad I found a use for them. If I were to purchase a new set today I would look for slightly shorter standoffs - but works fine for this application - good enough.As I marked 4ea dots on my case with a magic marker, I realized how difficult it was to drill the steel-  the drill bit kept running off and caused a few scratches back there from runaway drill bit. I was balancing the front of the case on a folded pair of bluejeans and resting the Z-axis on a small styrofoam block. I was very careful not to damage the screen. I also taped a piece of paper inside where I was drilling - making a paper pocket to catch steel shavings while drilling. Utimately what worked for me was to use a Dremel 395 with a  fine tip diamond embedded point to make an indentation dot where the stndard drill w/drill bit wouldnt wander off. A nail and hammer would also make that quite easily BUT WOULD DAMAGE THE mainboard and LCD - DONT DO THAT. The Dremel did it safely and without bending or warping from hammering.

I found a nice out of the way- unobstructed place to mount the MOS board and other than a couple of scratches from a wandering drillbit - it turned out perfect. (see attached photos) The most important things are 1. No metal chips to cause electrical shorts 2. No damage to LCD screen. A couple of scratches are no-big-deal but could have been avoided if I used a diamond bit on my Dremel originally - oh well ... live and learn. Also the holes were deburred with a hand deburring tool - to remove any sharp edges or fragments leftover from drilling- with a chunky fat drillbit looking handtool that I purchased online years ago.

Update 12/1/16
I received the 20ea XH2.54 2-pin white connector male/female with metal crimp on terminals.

Update 12/4/16
For about a month, I have been incorrectly under the impression that my 3d printer is the cause of of incorrectly sized g-code files. But today I have noticed a glitch within Cura 15.04.6 in which it in intermittantly scales the object incorrectly. After playing with it I kinda see that after loading a file and simply opining the scale icon and clicking on the several lines without changing anything- that the rendered object chnges size. SO all this time I printed the 25mm calibration cube and it actually printed 12.5mm- that was Cura's fault - because today I printed several actual size objects - by playing with this size glitch intermittant- and I can get it to make a genuine file that prints the correct size.

Im glad to see my printouts are the correct size. I WAS simply going to scale them - but when I scaled them - by the factor they were too small - then they were too big. That didnt make any sense - thats when I went looking for a glitch and found it - in 15.04.6 which is probably the last version for Windows XP?

So I have loaded both 15.04.6 and 15.04.2 on my system and see what works for me and my 3d printer. I know 15.04.6 has the sizing issue. I hope the lder version does not-  as I played with it - the older version seems to not have that glitch.

Alunar LCD "fan 0 to 100% setting for "board fan" controls the fan on the extruder. This fan is on when I turn on the machine and also when the extruder is trying to heat up. This looks odd to me and Im wondering if the board fan port is connected to the wrong fan? I think the extruder fan should be connected to "E1 or E2 fan" I havent changed anything - this is a hunch at this point. I also noticed that my extruder was wiggling during the print and affecting the alignment. So I iscrewed removed the fan shroud and plastic fan. The design of the hotend and shroud is much different than Monoprice Select Mini. Mine has a light brown tan middle and a square hotend head- I screwed the square hotend head onto the ceramic? middle by twisting as it had a thread. So somehow the square hotend head was unthreaded? I reassembled and seems to be secured better now with no wiggle.

Mk2B Heated Bed Special Size 120mm.jpg Mk2B Heated Bed Special Size 120mm.jpg
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M3 Screw Size for MK2B 120mmx120mm.txt M3 Screw Size for MK2B 120mmx120mm.txt
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M3 Thumb SCrew Nut 8ea.jpg M3 Thumb SCrew Nut 8ea.jpg
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360W 12v Power Supply.jpg 360W 12v Power Supply.jpg
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Chitu Mainboard Controller.jpg Chitu Mainboard Controller.jpg
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add-on Chitu WiFi.JPG add-on Chitu WiFi.JPG
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Chitu WiFi Install.JPG Chitu WiFi Install.JPG
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HT5_08 Terminal Connector.jpg HT5_08 Terminal Connector.jpg
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XH2_54 Wire 20cm.jpg XH2_54 Wire 20cm.jpg
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100k OHM  Thermistor 3950.jpg 100k OHM Thermistor 3950.jpg
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102816 White Dollar Tree Store Wire Cover.JPG 102816 White Dollar Tree Store Wire Cover.JPG
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Chitu 2-pin Connector XH 2_54.txt Chitu 2-pin Connector XH 2_54.txt
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Radio Shack Standoffs 4-pack 276-195.JPG Radio Shack Standoffs 4-pack 276-195.JPG
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Update 12/20/17
I have been experiementing with printing ABS onto Egg Carton flat sheet. When I buy a dozen eggs - I save the foam carton top- which I can make 2ea small square flat sheets. These sheets make a good surface for the 3d printer to adhere ABS to. Since I have not yet completed my heated bed upgrade yet. I find that the factory stock printer can print directly onto egg carton foam. The hot end slices through this foam - as if it wasnt there. By printing a raft, the abs object then seems to be fully formed. I have made a few test prints of miniature objects printed on the foam sheet and supported by a raft.

Also very recently I purchased a vintage Stratasys Genisys XS and so that makes 2ea 3d printers. I would like very much to make enclosures for some of my test equipment. My 3d printing skills are still in progress.

Update 12/30/17
I have continued my ABS 3d printing experiments and have reliable good results at this time so I will list details here pictorially regarding my settings. I successfully printed the 50% sized toy tugboat which is a test figure- and completed successfully with good results. I also printed a 1/2" diameter double-sided gear successfully.

My major change is printing on styrofoam plates from Dollar General - cutting a rectangle or square and then gluing the back of the styrofoam and also gluing on top of the kapton tape- then adhering the foam piece and securing it with tape so it can dry flat without raised edges for a few hours.

I find that the print comes off well when done and peeling off the styrofoam is not a major chore- although there are a few spots which a wet piece of tissue paper going over a few times will remove - leaving only the kapton tape. I have repeated this a few times and I see no damage to the kapton tape and I endup with useable prints. The bottom of the print needs to be scraped with a utility knife as the styrofoam melts and needs to be scraped off the print bottom. Thats better than not getting any useable results at all with ABS. Now I get successful small prints. Im not sayings it is the ULTIMATE BEST settings ever - but in my opinion it is working VERY WELL and it is drastically better than my other attempts.

I still have to solve a very slight almost-imperceptable lean to left-right-front-back which gives the print a very very very slight lean vertically. I see the hot end is attached only at the top and the print end is a couple of inches further down - ideally the printhead should be supported a little better - I will consider a small modification - but at least the print settings in the software are now figured out. The slight lean in the printed part is almost imperceptable. I corrected this as much as possible by repositioning the shims which the factory inserted below the hotend's flat metal piece. Supporting it from below is also needed and I need to think about/plan/consider how to solve that. But for now - Im so glad to see some positive results.

BTW the positive results are on an UNHEATED printbed - aint that something!

Here are my good working settings and some photos in this zip file for my Alunar R-100 3d Printer
Update 1/3/18
I am pleased that I have completed my Heated bed upgrade and have been using it for solid infill ABS printing successfully.
My heated bed has one layer of Kapton tape and then I pt down one very even coat of Elmers purple Gluestick just as U am turning on the machine and begin preheating to 90deg C. Print nozzle set to 245deg C. I have also stabilized the "Leaning" effect which I previously thought was the printhead - but is not. I have inserted rolled foam next to/under the bed adjusting screws - so the wiggle/lean of the adjusting screws wont affect the print. I have included photos of the foam inserts- which work excellent.

I remove a print by removing the heated bed (unplugged and unpowered) and take this cooled off  heated bed into my workshop where I hold the heated bed perpendicular to a block of wood on my workbench. Then I use a scrap but straight aluminum block above the print and hit the aluminum scrap block with a rubber mallet. It sometimes takes a hit in different spots to get the 3d print to release from the gluestick and Kapton tape. I find that the print is clean and straight. I like to print miniature gears and I find that the gear teeth are nice and straight and well formed. I dont see any curling or warping of the parts I have printed so far.

I have experimented with Cura settings alot and I find that setting my filament to .165 gives better results than .175 because my actual measure with a caliper is .164 filament thickness on my current roll of filament. Also I have changed the infill to 100% where before I had it set to 15% and this left all of the miniature gearteeth hollow - Im glad I fugured the cause out. I like 100% filled not hollow ABS prints for super strength. It prints very slow and I get very good results with fine details. Im very happy with my present settings. Here are my working good settings. I no longer use foam sheet as the heated bed and gluestick work well and the underside of my part is now super straight and clean. The only difficulty is in removing the part - but even so it is worth the effort to obtain a perfectly made part. I feel that I have accomplished my goal and my upgrade project is complete and working fully. It is everything I hoped it would be- parts are detailed and straight in ABS.

Since my machine is now fully working I am concentrating on my goals of making project cases and parts/pieces for my other machines which are in need of these parts. I feel that the 3d printer will make wonderful parts.

See my own webpage here for my 3d printing service "3d Printed Parts and Gears"

Here is a photo showing some of the many 3d Printed parts that I have created. Some didnt come out perfect the first time and I had to keep at it to change my CAD drawing or modify the print speed/settings/temperature etc so that the print turned out well. This is not a new technology. It has been around for close to 2 decades. It started with a 3d Printer called Stratasys Genisys (I own one - probably one of very last in existence and mine still works just fine) see my own webpage which chronicles my purchase or spare parts and the machine itself and its repair.

My go to daily use 3d printer is the DIY upgraded modified Alunar R100 little tiny 3d printer as most of my DIY replacement parts needed are miniature or small. It exceeds my expectations in fine detail. The completed perfect Gear teeth shown are very well formed and sharp straight. Some boogered imperfect botched attempts are shown too as this is real true honest photo. Sometimes making one good part takes multiple tries to get just right.
Egg Carton Styrofoam Inserts.JPG Egg Carton Styrofoam Inserts.JPG
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Update 2/22/18
As the layer of Kapton tape wore out due to many parts and test prints- I ordered a new roll from big-auction-site for $13 for a 100mm x 100Ft roll. While I was waiting for it to arrive, I experimented with just putting Elmers Gluestick directly on the very smooth surface of the aluminum heated plate. I found that the prints actually turn out better this way. The bottom of the part is very flat and gets adhered well. Also it is much better when trying to remove the part. The Kapton actually makes it stick too much and tears the Kapton sometimes. For now I am leaving a hole in the center of my Kapton tape of about 2-3 inches diameter - which is the part that actually tore and wore from use. I patched it when the new Kapton roll arrived - but the very first print ruined that patch so I removed it.

Also I have been experimenting with "bridging" which is something that my more complex CAD drawings require. I have somewhat switched from Cura to Slic3r software because there are more settings available to tweak than Cura. Those extra setings have alot to do with bridges and overhangs. I have found that I can actually somewhat make overhangs with ABS but Im still learning. I also find that there are more dimensional accuracy tweak settings in Slic3r software which helps me create holes and outside dimensions that are very accurate. Just today I made a thin walled tube-like part on Slic3r software that  turned out well, and I tried many times to make a good one on Cura without success. I think that Cura is a good software for certain type of parts - but the type of parts that I make require more settings to accomplish. So far I like slic3r software and has helped me to make a better accuracy part. Of course Im using older versions of both software which runs on my older Windows XP laptop- newer versions may not have those issues.

Here are my ABS settings for Slic3r software which seem to work pretty well for basic mechanical parts and replacement parts. Im not saying its the end-all-be-all but works ok for me on Slic3r version

Update 3/17/18
I have successfully printed a "Marvin" test print with perfect overhangs and the loop was nearly fully formed with very slight imperfections in the loop on his head which I fixed with a utility knife. This "good enough" test print is a milestone and Im posting the Cura 15.04.6 profile here.

Note that I have nver used any other plastic for this printer only ABS. I have no idea how these settings work for any other plastic. I just use the cheapest ABS filament ($10-20 through big-auction-site) which prints just fine.

I have completely discarded some settings from my past experiences. This supercedes all my other settings and etc etc. The major change is I NOW USE THE Built-in FAN. That was the only way to print a "Marvin" Test print because it has overhangs. I feel like I never even tried it because of the advice I received online - that you can ONLY print ABS if you fan is off (false). Well I now know that printing ABS with a fan on is a workable solution. I use a 35% fan which allows "bridging" and overhangs. With the fan off (my former mindset) I could not make overhangs. Also another change is having the printhead move to the side for awhile - to allow that layer to cool. During the "Marvin" loop- the printhead goes to one side and waits until that layer is cooled. Then it starts the next layer ... The loop is more brittle. The rest of the "Marvin" feels like normal everyday plastic. The loop is visually there but easy to crack off. The backside of the loop has some "schmutz" but it aint half bad

I printed directly off aluminum heated bed with gluestick. See actual photo which shows the printbed and the actual print. I was amazed it worked. Very smooth fine details and shimmers like a silk string covered Xmas ornament ball.

1-1/2 years of trying this/that and Im pleased with the result. Im not saying the ini file is perfect. But it is drastically better than my previous settings on formerly "unprintable objects". I have just today removed Kapton tape completely from my printbed. For a long time I was just using the printbed area which was missing the Kapton.

to use this profile for ABS
(save your old profile first as this will over-write your settings)
1. Load Cura 15.04.6
2. In the menu choose "Open Profile"
3. Select this file which I created
Marvin test Print Pic Backside ABS 031718.JPG Marvin test Print Pic Backside ABS 031718.JPG
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031718 Marvin Test Print Grey ABS.JPG 031718 Marvin Test Print Grey ABS.JPG
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Geiger Counter "Bella DBG-01N"  БЕЛЛА ДБГБ-01И

Made in Ukraine or Russia. My unit is brown plastic and some similar models were available in white, red or other colors and stickers. Some units are marked DBG-01i (mine is not marked with an i) Since I dont know Ukraine language - it looks to me like this model should be called Benna or Bevva or gEVVA or bEVVA or who knows what the correct transaltion is. But when I look online - I see that most people refer to this model as "Bella Geiger Counter" and by searching under this - you will find many videos on youtube and online websites selling parts and units.

I purchased mine in early 2015 in non-working condition from big-auction-site. I plan on restoring its functionality and will post my repair here. I estimate the date of mfg is approx 1983-1989. This was a very popular unit and many people used this model during Chernobyl accident to monitor levels. It is one of the industry standard models for obtaining readings and uses 1 internal sensor SBM-20 tube which is sensitive to Gamma rays and X-rays. It uses one standard 9v rectangle battery.

Also see my other webpage

The other webpage of mine - has to do with restoring a scanning electron microscope. I am concerned about getting irradiated / x rays /gamma rays from this equipment if improperly adjusted. So I decided to buy a geiger counter so I can avoid that harm. SEM microscopes are not considered unsafe as they tipically produce xrays internally but are well shielded. However that is refering to a properly working SEM. Mine is a fixer-upper and I need this geiger counter to make sure I set it correctly and maintain it.

Another good use for a geiger counter with X-ray abilties is testing of vacuum tubes - specifically picture tubes on TV sets. For example obtaining a slightly better brightness on an old picture tube - may make me crank-up slighly on the flyback transformer but only slighlty. See if the flyback is tweaked too high - the filament inside the "picture tube" yoke/neck at a certain poiuntg will produce unwanted xray or other radiation.

Radiation is not a toy and I see too many people using their geiger counter to play with radioactive rocks or other objects while listening to the Geiger counter "going nuts" ticking and beeping its warning while the user handling the samples. I suggest that people who use their geiger counter - should use it to save themeselves from harm -rather than as a toy. Specifically - if the geiger counter shows an unsafe level - take immediate action to avoid exposure or correct it so that the source is put-away/solved safely. Thats my advise.

A reading takes about 1 minute.

My General Operating Instructions Notes

1. Top button is reset (LED will flash as an aknowledgement when momentary button pressed)

2. Rightside Buttons (slide up down switch to select)

    A. Upper is Audio Click ON/OFF

    B. Lower is Power ON/OFF

3. Place unit at or near source. Press reset to begin new counts. After approx 40seconds the display translate the number of counts into a whole number with decimal point and additional disgits. This number is your micro sieverts per hour. This meter has an accuracy of within 30 percent plus or minus. Gamma and Xray sensitivity only. Use only as a guide and use your own best judgement on what is safe or not. Its not going to pick up every ray or even close to all of the rays that may be or may may not be present.

I can tell that this will be a difficult circuit to diagnose because the IC chips are not in English and the electronic components are different looking apearance-wise and marked in a differnet language. I will need to figure out English equipvalents and use my best judgement and equipment to figure out what is the problem with this non-working unit.

I see normal background safe/normal radiation counts is somewhere between 10 to 25 clicks as typically displayed on this model. It has a 4 digit LCD display which looks like this Often on this model's LCD display there is some black bleeding internally as the liquid crystal seeps or glass separates or cracks etc. I see no bleeding on my own LCD which makes me think it was never exposed to extreme cold. LCD screens are damaged or destroyed by extreme temperatures both hot and cold. I felt that this unit on big-auction-site was worthy of putting time and effort into fixing as it is physically in good shape and complete - right down to the battery cover.

Update 1/15/15

I received my geiger counter and got it to work and un-modded it as much as possible. I have posted a more detailed description of what was done on my "scanning electron microscope" page. It didnt need any electronic component repair or replace. It was just a matter of un-bodging it bringing as close to original as possible.

Update 6/2/16
Unfortunately my Bella Geiger Counter is not working. I wanted to use it to test a CRT inside my film equipment which scans using a flying spot scanner - when I went to my cabinet to get my geiger counter - it was in a ziplock bag and no 9V battery installed. I put a fresh brand new battery in it and I see all zeros O.O.C.O and one of the zeros is incomplete "C" due to one of the LED segments unlit. I see no incrementing or tic tic tic. It is unresponsive. I pressed the zeroing button on top of the unit and red LED lit but I see no sensing of background radiation at all. So unfortunately I was unable to test my CRT inside my film scanner (one of several extra parts units which I am trying to rebuild/restore/combine into another good one) which I am currently repairing. I dont know how it could be non-working as it has been undisturbed in the cabinet and safely stored. I enjoyed using it and I hope to find time someday to fix it. I used it about 12 times in the last year and was a very useful tester. I didnt do anything to cause it to die - was just stored in a cabinet.

Update 6/7/16

I decided to open it up and see what is wrong. I tried 2 batteries and still was stuck at O.O.C.O and I disconnected battery and tried moving the bodge wires and then reconnect battery. No change. Disconnected battery and then tried moving all of the components over just slightly - that was it a loose connection on one of the components. I reassembled after it worked. I didnt touch up any solder joints. There is a certain point of - "if it aint broke - dont fix it" Im glad that it works again- one segment of the display shows a C rather than an O but nonetheless - it is useful again. Normal background radiation differ from minute to minute but is somewhere around 7 to 13 clicks. If I put it on a stack of extra floor tiles I get a couple more clicks around 13 to 15 - so I can cell it is working normally and LCD numbers are incrementing now. The mfg coated the PCB and components with a clear coating (varnish? Clear paint?) and I dont wish to disturb that - so it works and Ill not reheat all of the solder connections.

Bella.pdf Bella.pdf
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XRAY of Identically marked chips showing the internals (above pictured) Sometimes alike marked parts can be significantly different in design and may have a incompatibilities. Testing is best - even with like-marked parts or parts which are visually identical.

VZ IC Tester pictured above (list of chips shown at bottom of page on left side in blue) My IC Tester # 3

It has search function and chip number can be manually typed using the keyboard. This tester was sold under 2 different brand names. The components on the internal circuitboard are sanded to hide part numbers- which makes repair very difficult as only good working chips are identifiable. The case is not precision molded - it is a heavy plastic which is slightly imprecise - the battery lid does not open/close easily due to this imprecision. Much care in handling the battery cover is needed. The vendor sent me a replacement battery cover at no charge. The vendor was helpful. This is a very nice tester and at the time I purchased it - it was the lowest cost handheld tester available. It does a good job identifying / searching for unmarked chips. I bought mine through big-auction-site. Later this same mode was sold through a commercial online big retailer for more than twice the price I paid for it.

Manufactured and purchased new in 2012 year.

Update 12/15/14

I caution the users of this tester and rebranded/original model which bears a different name. This tester has a very small tolerance for deviance in supplied power. It will blow out if any ordinary power adapter is attempted connected. I suggest ONLY running this IC tester on 9v battery. Internally some chips have been sanded down removing the identifucation of the chips. This renders the tester difficult to fix by end user as identifying a non-working sanded-down chip is not possible. Heed my advice and only use batteries. The instruction manual gives the wrong voltage for the dc power port- dont attempt to connect 9v with a wall type adapter to the external power jack. Heed my advice and only use internal battery.

GUT IC Tester pictured above (list of chips shown at bottom of page on left side in white) My IC Tester # 1

It has search function and chip tested can be manually selected from internal Menu lists. This tester was sold under various names by several vendors. The diagram on the front of the unit is handy - it tells you which chips to install up orientation or down orientation. The down orientation chips need to be at the bottom of the socket. The up orientation chips need to be at the top of the socket. There is a clearly marked OFF procedure. (on another brand this off procedure is not clearly marked - see my LIC tester further down on this page)

I bought this used and had a heat damaged LCD display. I ordered a new LCD module which is a standard type. This tester now performs very well and has no cosmetic or functional issues. If I didnt tell you - no-one would know it had been repaired. The only difference is the LCD contrast is higher on the new lcd module than on the original (original LCD was dim) and display has a slightly greenish color.

The aftermarket LCD module was purchased on big-auction-site " HD44780 16 Character x 1 row LCD display w/light " and the original one was not backlit and was damaged as received from seller - bleeding LCD symptom towards the center. A perfect replacement non-backlit (jujst like original) screen choice is 1602 16character x 1 line - instead I chose the backlit version and had to modify the internals slightly to make it fit as it is thicker. I have not hooked up the backlight. It runs fine without the backlight. At this time I have not figured out where to connect the backlight pins - the screen works beautiful but no backlight at this time.

Manufactured approx 2005 year estimated. Purchased used in 2012.

Precision-Motion Chiptester Model CT2 pictured above (list of chips shown at bottom of page on right side in red) My IC Tester #4

Notes: This is the full version machine with optional internal ROM upgrade factory pre-installed (" CT1 with 4164 & 41256 TEST "). Originally sold by Digi-Key Part Number CT2-ND in approx 1988 year. There is no keypad to enter the chip number. Simply insert the chip into the socket. The manual tells you the correct display for a good chip. Usually the display shows the last few numbers of a chip - as the correct response for a passed test. On other chips the display may show a letter and number combination or simply a number or a subtraction symbol next to a number etc - the manual deciphers the display and what it means. Reading the patent also helped me understand what this tester does. It is very sophisticated yet simple for most chips. There are some chips in the list which require 20 adapters to be self-made as some pins on the self-made adapter need to be cut-off or jumpered. I do not have any of these self-made adapters. Between all of my testers - the chips which the Chiptester requires a special adapter to be self-made - are available as part of a built-in test on another one of my machines. It is important to look up the chip number in the manual before plugging it into this tester. Estimated manufactured 1988 approx year.

This IC tester was purchased used in 2012.

YBD IC Chip Tester pictured above (list of chips shown at bottom of page on right side in yellow) My IC Tester # 2

Purchased and manufactured New in late 2012 year online from a Hong Kong Seller. Purchased the optional add-on 3-socket adapter 2013 year direct from the mfg. No automatic search function on this tester. It has loop function. The number of ICs this unit can test is very very extensive. For some ICs - the chip must be put with pin one at top of ZIF socket - other tests require the chip to be put in with pin 1 of chip to pin 2 of the tester socket (the display prompts the user how to insert after the chip number is entered.) The manual's diagram showing how to use the adapter differs from the markings on the 3-socket adapter - so I have not plugged this $40 3-socket adapter in at all. The mfg is checking on this to see if they can provide me with an updated instruction sheet to clarify the proper use of this adapter board.

Update 2/25/15

The mfg never did provide the missing information (but I did get responses to email). I paid quite a bit of money for the adapter board plus Western Union fees and it added up to be alot of money. But I'm glad to have this board. I have communicated with several buyers of this same IC tester and one of them also wanted to buy this add-on board but was told it was not available. My understanding is that the person who created this add-on board (mfg former employee) is no longer there and the current employees do not know the answer. Also the board was not available for purchase - another owner was told they dont have any more.

So that makes me the only person who actually has this board - possibly?

I studied this board thoroughly and have created an instruction page on chip orientation and orientation to plug into the IC tester. I didnt want to run the risk of just randomly trying things - so I carefully studied the board and determined how each pin on the board leads to each pin on the DIP male plug on the end of the ribbon cable.

The basic purpose of this board 

When you type in the chip to be tested from the chiplist - you enter a sequence of numbers corresponding to that chip. For example when you want to test chip 8255 you key in that sequence on the keypad. Usually chips can be tested directly on the console. But for certain chips on the chiplist the display shows OU-1. This display tells you that the testing of this chip requires the "Special Device Testing Board YBD-5" (see my photos of this board). The manual that came with my tester is mostly understandable but leaves you scratching your head on certain topics. Especially regarding the add-on board. So I wrote my own manual for the YBD-5 board. I also put homemade stickers on it; So, I know the orientation of the ribbon cable and orientation to insert the chips into the sockets.

Here are some photos of the board, my own instruction page, and other misc photos showing my actual unit in its protective packing material. It is a very nice IC tester - I spent alot of money on the tester, shipping, bank fees, western union fees, add-on board, etc. Was it worth it - yes I'm glad to have it. I can test chips that are unique to this tester- also it is a good second opinion and pulls its own weight in determining faults.

I had to figure out the answer to my own questions. I was basically on my own regarding this board. I feel that I understand it now and took alot of effort on my part.

What is not clear in the MFG's manual

1. Orientation of ribbon cable and red stripe side

2. Orientation of chips on the sockets

My photos show the correct orientation. The instruction manual explains how to use the add-on board, orientation, schematics/board layout and traces, etc. It is not often I use the chips that the add-on board handles - but I can now refer to my own manual to refresh my memory. I never have to fumble around with this anymore. Now I can use it. I printed the manual on my color laser printer Samsung CLP-300 which I purchased a few years back at OfficeMax on closeout/demo unit. It prints beautiful glossy perfect pages. I use that printer very sparingly only for important things. What I'm trying to say is this is a beautiful instruction manual - I put my best effort into it.

They didnt make 3 separate adapters - but instead combined it into one board. Either way works- but schematically it would be much simpler if it was 3 adapters. The display tells you which of the three adapters to use. But since there is ONE adapter board - you plug the chip into the corresponding section of the board. All this adapter board does is cross and switch around a couple of pins. Its just wiring traces. There are no electronic components on the add-on board.

Dont jumper on this tester (some other testers have you insert jumpers between pins or add capacitors to certain pins) - BUT I WARN YOU - jumpering is not applicable to this tester. Certain pins must be raised and then that pin is crossed to where another raised pin is - basically switching pins around. Thats basically what this adapter does. If you simply jumper - you'll short something out inside this tester- dont do that.

One funny thing about this tester is the word "PLEASE" is displayed when it is ready to test. A better choice of word is "READY" It makes a beep boop type sounds which remind me of a Milton Bradley SImon game from the 1980s.
I like this tester - it tests alot of chips including some older computer motherboard type support chips.

Update 6/7/15
I see a youtube video (not my video) which gives a good basic demo of this tester. The author is speaking in a language I do not understand. I understand English and Spanish and am able to pick out enough similar words to understand this video's narration.

Copy and paste into your web browser

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MCT IC Tester pictured above (list of chips shown at bottom of page on left side in green) My IC Tester # 5

Made in 1989 year approx. Memory chips DRAM are installed in the test socket reversed/backwards and furthest away from LCD. Has auto search function and also arrow keys to select chip from internal list. I have the version with the yellow button (some other units have a red button) Purchased used in 2013 from USA seller. This is a very speedy tester and with a press of a button recognizes a chip and tests it very speedily. You can also manuall\y select the chip number from a chiplist and scroll through that list. It runs on a 9v standard battery. Memory chips are tested upside down (notch facing user) and TTL chips tested up-side-up (with notch facing away from user)

I had 2 identical units and gave one to a family member (both purchased from same seller) Both units had a dim LCD display. Dim LCD  is normal for this model. Use it under a good light source such as a lamp.

The above image contains text written in an international language. It is a mystery what the "P" key does. This image contains words which describe the function of the O and P keys and this page needs translation. Do you know how to read this? The instructions do not state what the "P" key's function is?

I believe this language is from Singapore possibly? As Singapore is where my TSHG-02F was purchased from.

Translation of the above picture is appreciated.

Update 5/7/15
I received a very vague translation of at least one part of this photo from a big-auction-site seller who wrote that the TSH-06F "P key" is for backlight and the "O key" is for quick power on / off. I was emailed the internals of the "blue tester" and the insides have no backlight on the LCD screen. The internals of the "Blue Tester" show a series of 4 through-holes labeled "pro" and a large odd looking resistor (the rest is surface mount components and ICS) and two adhacent solder points - also the ribbon cable leading to the LCD may have one unused line - if in fact this backlight function was implemeted onto the board. The "yellow tester" TSH-02f (Which I have) has no P key or O key. I see no backlight or prog function in the menus. I have added 2ea zip files here which contain the insides of the 2ea TSH testers. As an interesting trvia - the blue TSH-06F is silk screened on the internal board with the words "ABI Chipmaster"

I wonder if the 4 +2 pads on the TSH-02F and the 4ea "Pro" thru-holes are programming points for adding to the internal chiplist and other functions. The backlight is the least of my concerns as the tester perfoms very well and is just fine with a non-backlit screen.

TSH-02F Singapore tester instruction TSH-02F Singapore tester instruction
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TSH-02F Demo.flv TSH-02F Demo.flv
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My TSH-02F My TSH-02F
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The Blue Tester is often advertised with the set of features of the yellow tester. There is an added feature of O+ENTER for power off. The instructions included with the blue tester for many original buyers of the blue TSH-06F tester as many came with the instructions for the TSH-02F. The following photo is in a different language but clearly shows that a combo of buttons O+ENTER and other combinations perform functions (unable to read this language so it is unclear which key combinations perform fucntions. As of this writing the yellow tester is becoming rare to find 6/14 and I only see the blue tester TSH-06F being sold on big-auction-site. Functionally these 2ea models of testers are alike except for Off key and P key combinations. The blue tester also displays "self test Pass" (as shown in one advertisement) whereas the yellow tester internally self tests but doesnt display the message. If the yellowe tester fails the self test function it will display ERR 1 or ERR 2. This is a very speedy tester. It runs on one 9v standard battery for the TSH-02F (Yellow) and 2ea AA batteries for the TSH-06F (Blue) there is a built in voltage check meter which you can monitor the battery voltage remaining in your battery. It is interesting to see how much the battery drains after x-number of chips tested. I have not counted how many chips I could test on one battery set. Some tests of certain ICs and certain components drain the battery more than others. I sometimes use a standard battery and sometimes a rechargeable 9v battery for IC testing.

As of this writing I am unaware of the purpose of the P key. The answer is probably contained in the jpg file but since I am unable to read that languae - I dont know what the P key is for. I assume it is for self-test but I dont know for sure that is only a huinch on my part. If you have a blue tester and figure out what the P key is for - let me know.
Blue Tester Self Test and Power Off O & P.JPG Blue Tester Self Test and Power Off O & P.JPG
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TSH-06F tester showing TSH-06F tester showing
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The Black TSH tester shown in this video is not crystal clear which model it is - please note that the zener diode shown in the video is connected to a different 2ea pins than the video for the yellow TSH-02F tester.
Black TSH IC Tester.flv Black TSH IC Tester.flv
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Type : flv

TSH IC Tester pictured above (list of chips shown at bottom of page on left side in orange) My IC Tester # 6

Purchased new in early 2013 year from Singapore. Tests Digital ICs, a few Linear/analog ICs, Zener diodes and a few more. I imported this tester direct from the mfg and is one of the first few produced. This device did not come with a list of chips - but the instructions specified the families of chips that it can test. I enter the family in the menu and then choose the chip number within that family and in most cases this tester handles it well. Not all chips in every IC family series are supported - as I find out sometimes when it displays "not supported" meaning that this chip is not on the internal list. This tester is great at differentiating between LS (lowspeed type) and HC (highspeed type) chip types.

There was no chiplist included with this model of IC tester - I have created a chiplist for it - see the bottom of pages. I have manually gone through each and every chip in the internal menu one-by-one which was a laborious task. I made notes on which chips it recognized and which ones were not supported. Why the mfg didnt include a chiplist - I dont know - but I have one now because I made it myself - the hard way. This chiplist is identical in both the TSH-02F (Yellow) and TSH-06F (Blue) testers. I used up 1-1/2ea 9v batteries making this chiplist - with no chips in the socket - just going through the menu and looking to see if LCD display has a reaction to manually entered chips to create my own chiplist.

Update 8/23/15
I see 2 sellers on big-auction-site which have the model TSH-06F advertized as a "SainSonic Digital IC Tester" and over 20 other sellers have it at the $40-55 range and do not list any namebrand. One seller has this item listed for $36 and has sold 5 of 6 at this low price.

In response to my "translator wanted advertisement on Craigslist - I received a reply about a month ago with another partial translation - again stating that the P key is for backlight and further stating that he/she would tranlate the rest of the document at another time - but never heard back from them.

Here is a screen snapshot of 1 or 2 ads which states "SainSonic" - I have blanked out the website and sellers name etc to keep it generic.

SainSonic TSH-06F IC Tester.JPG SainSonic TSH-06F IC Tester.JPG
Size : 95.482 Kb
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Here is a text file in Word format - you can use an online viewer if you dont have the soft ware "Word" But this is just your average instructions in which it says the P key is for backlight. Another ridiculous online instruction in which it gives false information - can anyone reading this translate the image which contains foreign language text - that may contain better information?

TSH-06F Operating Instructions.doc TSH-06F Operating Instructions.doc
Size : 43 Kb
Type : doc
Update 11/20/15

I finally feel I have a complete answer to the question of what the O & P keys are for.  The P key is a backlight and I was told by a person who I have LONG since blocked on my emails as he was writing saying that his TSF-06F doesnt have any backlight and the P key being a backlight on/off makes no sense. He went as far as sending photos of his LCD and boards internally and it is not a backlight capable LCD.

So my only conclusion is that some early versions of TSH-06F are not backlight capable and some have backlight. I can clearly see in the following youtube video - that the IC tester in use DOES have a backlight.

Here is the video (I am not affiliated with this video which has some good repair tips)

See in this video - the youtube TSH-06F really and truly does have a backlight. And yet one person has showed me photos of the internals of an early model which does not have backlight.

As I look on big-auction-site - there are at least a dozen vendors selling this TSH-06f and  see no photos of the LCD screen with a backlight on. It is unfortunate that the sellers use "factory stock" images and data and didnt take the time to post actual hands-on photos. I hope this update and the video link clarifies a few things about this model's P & O keys and what they do - at least on some versions of this tester.

Update 9/7/16
On big-auction-site a seller is selling 1ea used TSH-06F blue ic tester for a low price. I asked a question by replying to his ad. My question was whether thebacklight worked when you press the P key. His reply, "Hi - I'm not aware that there is a backlight in these units - at least the one I have does not have a backlight that I am aware of and in fact my "P" key does nothing..." I didnt buy this item as Im looking for one that has a working backlight.

My point is that it is very likeoly that the buyer will receive a non-backlight do-nothing-P-key unit. Make sure you ask the seller or vendor to confirm that the P key works and produces a backlight. I have noticed that the price has decreased down to an average of $35 whereas about a year ago these were selling for about $50. Some sellers are still higher than the average. If a backlight is important to you -make sure you get them to confirm that the backlight function works.

Update 12/26/16
I see a youtube video demonstration of the China IC Tester which looks identical to the "Blue IC Tester TSH-06F" in which I have been looking for one with a working "P" button for the backlight. The youtube author is reviewing a China IC Tester (not my video) and mentions that there is no model number and only has printed on it "IC Tester" The video shows the backlight ON when the unit is on. I deduce from this video that the $31.56 big-auction-site IC testers MAY have a working backlight.

TSH-02F Yellow IC Tester (Singapore) - no backlight
TSH-06F Blue IC Tester (China) - backlight button does nothing - no backlight model  "ABI Chipmaster on  PCB backside"
TSH-06F "IC Tester" - Blue IC Tester (China) - possible yes working backlight "No Model Name on PCB backside"

Im not affiliated with the following video (pardon the derrogatory comments during the video - yikes) Its a beautiful IC Tester and took alot of skill and talent and precision tooling to make it.

The outter apearance of the case DOES NOT indicate model number and only difference seems to be "ABI Chipmaster" printed on PCB or NOT. Also internally the LCD screen either has a backlight or not.

Ive not had any success in getting a response from big-auction-site sellers - on whether their unit has a backlight or not.

Buyer beware of sellers of old generation Blue IC testers - trying to trick newbies into buying a non-backlight model. It is possible that simply replacing the non-backlit LCD to a backlit LCD screen will upgrade the previous version fully - But that is only speculation on my part. I do not own either version of the Blue IC Tester from China.


Micro Scences MSI Digital IC Micro Circuit Tester Model ICT-101 (pictured above)

IC Tester #7.

(List of chips left side purple color - see below)

There is an empty socket on the front of the machine - which  is for 24-pin IC chip clip (was optional accessory - but mine doesnt have this clip. As I read from the book this optional clip is only for 74154 IC which is a narrow .300" IC same as most 7400 chips so a special .300" IC clip 24-pin is needed and these clips are uaully designated "24/3" to denote 24pin clip for a standard .300" narrow IC). I have 2ea total IC testers that can test 7400 TTL and 4000 CMOS chips in-circuit while the circuit is powered on (the MSI ICT-101 and the B&K 560). It is a large tester 5"x12.5"x11.63" and weighs 7.63lbs. This tester is estimated to be mfg in 1983 and is complete with manual and ground cable (Pomona Electronics 3780-36-0) and 20-pin ribbon cable with end clip. Most of the internal chips are 7400 series with 1 static RAM and several ROMs. There is a D800 microprocessor in there also. A board which looks like a memory module is covered in factory black epoxy resin to shield the part numbers and protect from anti-static. The 2ea upgrade ROM which adds a few more ic chips to the list - is not in my machine (I have the standard ROMs with 2ea additional empty sockets for the upgraded ROMs to go there. My sockets U10 and U13 are in need of the upgrade ROMs. If you can provide these missing U10 and U13 ROMs - let me know. I realize it will be difficult to find these ROMs 35+ years later.

Here is my photos and description of how I fixed my ICT-101 Tester. It is a free download and copyrighted All Rights Reserved. Do not post it in forums or share in any way. Instead - refer people to this page or give my contact info so they can download it from my webpage directly.

Update 5/29/15

I have acquired a second fixer upper ICT-101 (purchased Oct 2014) which has the 204 Rom Extended Chiplist stored on 5ea 2732 EPROMs. I am still looking for a 205 chiplist which is enhanced even further. As I work on repairing this second unit - then I can take advantage of additional testable chips- above and beyond the standard chiplist.

24-pin Ribbon Cable.JPG 24-pin Ribbon Cable.JPG
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Amphenol FRC D24 5 24-Pin.JPG Amphenol FRC D24 5 24-Pin.JPG
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This IC Tester has internal diagnostic checks and functionally tests itself in many ways when powered on. The menu lets you choose settings for ROM RAM CMOS TTL and more. My tester does not have the optional RAM/ROM test feature. My tester is a basic model and only for in-circuit testing of 7400 and 4000 series chips (this tester does not test every chip in these series/families of chips). The add-ons were not purchased by the prevous owner and this is a factory stock machine - now fully functional - after I replaced about $25 worth of discreet (common solder in place type) components and 2ea ICs purchased online. When I purchased it - it had a scrambled/garbled display (looked like this @#$%&*@# with all random characters) and was unresponsive to key presses. It had a bad transistor in the display board and a bad SCR and 2 bad 7400 series chips. The 1ea desoldered/now socketed static ram chip 6116 tested fine on my tabletop IC tester. Luckily the proprietary memory board was fine as the factory covered it with black epoxy and would have been difficult to remove epoxy. Since all of the chips were soldered in place - I had to make my own IC desoldering tool by hand and I removed each chip and socketed it. I checked each componenet one-by-one with a parts tester BK Precision BK815 & various handheld & tabletop IC testers shown on this page. The zener diodes I tested with Duoyi DY294 tester & TSH-021 IC tester which gave correct voltage checks (see above photo which shows germanium diode inserted into IC tester for voltage check)  Several parts were replaced with NTE brand replacement parts purchased from Radio Shack online and a couple of parts were purchased online internationally. I desoldered chips carefully and used the same chip to go back into the IC socket. I did not destroy any chip when I desoldered with my homemade desoldering tool and was able to test them on my IC tester and knew they were fine. The online auction I purchased this ICT-101 IC tester from says it was "military surplus". the preevious owner attempted to fix it and boogered up alot of things. It took alot of un-boogering to correct. I solder very well and my solder joints look pefect.

The general concept for using this tester is - you have to have a live powered-on board to be tested. But the board under test cannot be underway. What I mean by that - is the electronics have to be idle and not operating. Powered on but not operating. The microprocessor should be removed or the crystal disabled so there are no oscillations. The ground is connected from the powered on board to the ICT-101 tester. Very important - the ICT-101 needs to be powered on first before any connections are made. It tests CMOS and TTL Digital Logic ICs in circuit on live boards which are not underway. I hope I explained sufficiently - what I mean by "powered on but not underway" as I'm trying to phrase things in everyday terms. The book calls it "the board has to be in a static condition" and "devoid of active ICs" and "effectively removing disabling or tieing clock generators."

The tester should never be exposed to 6v or more (6v would kill the ICT-101 tester). Check voltage (This is a 5v tester only) before testing and removal of oscillations prior to use. The tester should not be clipped onto a chip more than 1 minute or it may weaken or ruin that chip. A sense of urgency in quickly testing a chip is necessary. You cant stop and answer a phone or shuffle papers while using this tester - otherwise you will burn out the chip under test - or damage the tester itself. Any possible future repair should be easy now that all the ICs are socketed. Test equiment should always have socketed ICs - that is my opinion - as it makes for easier repairs and fault-finding/troubleshooting. It is interesting that the mfg of this ICT-101 tester had a lifetime warranty on this tester and is no longer in business. The book states that an ICT-101 is necessary to troubleshoot an ICT-101. So it takes a tester to fix a tester. If I had another in-circuit tester - I could have removed the microprocessor, clipped on the test clip, and checked each IC one-by-one. That would have caught all of tha bad parts except the SCR- which would still have needed to be manually desoldered for testing out-of-circuit. I have alotof IC testers as a "second opinion" about a parts condition is helpful and avoids false pass/fail and replacing good parts un-necessarily. This in-circuit tester is one more "second opinion" about an ICs condition.

This IC tester was purchased used from a USA seller in late 2013.

Update 8/5/14 I have completed the machine by addiing a second ribbon cable in the righthand socket. I found a professional 24-pin IC clip and ribbon cable made by Logic Connection which is NOS New Old Stock purchased from big-auction-site. This clip was hard to acquire as it got lost in shipping for 3 weeks and ended up in another country. The honest person who received it - sent it back to the seller, and then I received it after about 3 weeks. I also added a 24-pin ribbon cable connector. This now gives me the ability to test just one 24-pin IC chip on the chiplist which is a wide style chip.

 Update 10/15/14 I have purchased a 2nd identical unit from an international seller. This unit was the sellers 2nd unit and didnt work- it had a scrambled display for example &%&%$@# is what it looked like. The seller then disassembled it and never attempted a repair and it sat in his shop for 10years disassembled. He sent me photos showing all of the major parts like boards and case and front and back panels. I have included those photos here which shows the as-is condition. I will chronicle the repair of this unit here. I suspect it has the same or similar bad components as my other ICT-101 tester repaired with the very same symptoms/issues. I suspect this model must be turne on and off very carefully with no bounce in the power switch otherwise the same discrete components and ICs fry - see my above article on which parts were replaced on my other ICT-101. I will need to wait a month approx for this non-working disassembled tester to arrive.

Upate 11/4/14 I have received this second ICT-101 and arrived from Brazil seller. The box was shipped very carefully and nothing heavy was placed on top. All of the parts arrived as sent with no shipping damage. All boards have corrosion and I knew the condition as the seller sent photos. It will take alot of work to restore. I am glad that all boards and small pieces were sent including all screws in a plastic bag. I look forward to having a working second tester of this model.

ICT-101 Broken Unit Purchased ICT-101 Broken Unit Purchased
Size : 14287.619 Kb
Type : zip
Heres some nice clear photos showing another ICT-101 on big-auction-site. I am bidding but I may be outbid on this non-working "doesnt power up" machine. Interestingly - the seller is showing the insides too. Its not too often the seller takes it apart. Maybe that will be counter-productive in the final bidding/sale price - who knows. I have included these auction photos here. It looks the same as my 2ea units - no difference between units - as far as I can tell. I am inlcuding them here because they are nice clear photos.
ICT101 Auction ICT101 Auction
Size : 1384.474 Kb
Type : zip
I found a reference to "Inline Test Systems ICT-101 Automatic IC Tester" Here is a PDF file which contains the exact description of the ICT-101 IC Tester - except it is listed under a totally different namebrand. I have a hunch that it is the same IC tester - but possibly a earlier or later version. I dont know what the story is on why it has a different brand name - possibly a sister company or an early incarnation of the company name - who knows?. I dont know what was included in that price - I know there was a basic model and more advanced models capable of testing RAM/ROM and out-of-circuit IC chips. I dont know what what was included for that price. It is part the history of this IC tester - so I am including it here for reference. This ad also has listings for several other ancient computers and test equipment - it shows how vintage this tester ICT-101 really is. In my experience it works very well. It identifies and functionally tests chips in-circuit which is a very rare feature among IC testers. Through the "magic" of search engines - I recognized the ICT-101 description matches the MSI ICT-101 tester - same as Inline Test SYstems ICT-101. Same unit different brandname - that is my hunch.
I also know there is an IC Tester called a "Micro Concepts Boardwalker model 101 model 102 model 103" which is somehow affiliated with the MSI ICT-101. I emailed a person with an online resume which listed boardwalker development - I emailed that person and asked him a bunch of questions and it turns out that some of the same people developed both machines. He didnt remember much about it because it has been decades.

I see some reference to " backdriving " or " back driving " or " node forcing " which basically means in-circuit testing. I dont own a Boardwalker - but I have 2 other models/brands which do in-circuit testing ( MSI ICT-101 and B&K Precision 560 ). Or as some websites call it " backdriving " in order to test the IC. It's a great feature. It is amazing how few components and basic off-the-shelf ICs are used internally in these testers. The downside is backdriving puts stress on the IC being tested. My MSI ICT-101 manual warns to only leave the IC clip on for maximum 1 minute or damage to chip or the tester can result. The online articles about backdriving show alot of math and circuit diagrams and make it sound so tedious and complex. These testers do that very easily and quickly- the results on the LCD display is instantaneous - it finds the IC and identifies it very easily and immediately - no lag at all.
Boardwalker 102.JPG Boardwalker 102.JPG
Size : 27.337 Kb
Type : JPG
Update 5/25/15
I spent a few hours cleaning the ICT-101 which I purchased from San Pao Brazil Seller. I purchased it in 2014 and didnt know what to do with it until today. I was fearful of bugs or other contaminants as it looked it it was left outside disassembled. I purchased a big plastic storage container from "Dollar General" store for $9 and used about 2 gallons of water and about 1/2 quart of Green Cleaner.  I used a small paint brush to gently scrub away all of the dirt and particles. I have cleaned every part as much as possible and then rinsed in water and let to dry. I was careful with the switches and transformer and speaker - not to submerge in water or liquids. Some boards like the LCD board and the power supply board were not disassembled - I used cotton ear swabs to gently clean as much as I could safely.

I removed the socketed CPU and Socketed 5ea Eproms and put them on a scrap styrofoam piece labeled with a magic marker - with a diagram on where they came from and orientation. I will save these ROM images (I will not post the ROMs) as a backup in my records because ROMs do go bad. I am hoping these are the extended ROMs with an extensive chiplist. The stickers are illegible and I will need to put new stickers on. I was careful not to clean the ROMs or expose them in sunlight for too long. I cleaned the board - with all ROMs and CPU removed.

This was a nightmare project that I wrapped in a shopping bag (as soon as I received it) and sealed airtight with clear packaging tape since 2014. I wanted to make sure there were no bugs or other critters. Also one thing that has been on my mind for many months - which I solved today. The memory board has several rows of SIL single inline connectors. One of the pins was broken off and jammed inside one of the female connector holes. I was thinking about this problem for months. Today I came up with a solution - I used a sharp utility knife to gently pry up on the tiny pin - it was wedged in there. I got it out. Look at the photos - you will see a tiny metal sliver along with the screws. That is the pin that I got out. That is a great relief to have this unity cleaned and drying and the pin out of the hole. That broken off pin is probably why the previous owner never finished the project. He included a replacement inline connector - but it was a very difficult thing to remove that stuck pin. It is SUCH a relief on my mind to have this cleaning done.

Here are some photos in zip file.
clean ICT-101 Brazil clean ICT-101 Brazil
Size : 9903.353 Kb
Type : zip
Update 5/25/15
I received a tracking number from Italy seller today regarding a third ICT-101 which I purchased. I saw it on big-auction-site from Italy and somehow it showed up on google search (I search several times a week for IC tester auctions) and by some freak occurance this showed up on google search for one day. I paid the asking price and then was refunded same day - seller stated that she was offered a higher price. Then I replied that I can offer more and she basically doubled the price and sold it to me. This is a working ICT-101 which is 240 volts and she posted photos showing the LCD displaying properly and powered up and also includes manuals. It was shipped by the seller today 5/25 so I look forward to its arrival. My hunch is that the transformer is probably the same as 120V version ??? and by re-arranging the solder points on the windings - it can be changed to various input voltage. I will take photos of the 240v ac transformer when ICT-101 from Italy seller arrives.

ICT101 Italy Pics ICT101 Italy Pics
Size : 1563.903 Kb
Type : zip
Update 5/29/15
After letting the boards etc dry fully (after a thorough cleaning) I did 2 things today
1. Performed a general Lissajous testing on boards and power supply
2. Made a backup of my 5ea Eproms 2732 and saved to my computer

I see that every component on the power supply gives a vertical line Lissajous pattern- this tells me that there is a short present. It is strange that EVERY component I check gives a vertical line.

When I check beyond the power supply - I see the large mainboard has several component which test normally and chips give a normal reading.

I checked the LCD display board and found an odd reading on the LED which is a vertical line. Also some soldering looks very homemade and some solder joints look like someone started to use solder sucker.

This tells me that the power supply has an issue and the LCD board has to be resoldered as some pins on the LCD look like they may not even be protruding through the hole?

My 1st unit was a unit purchased from big auction site -  it also had VERY VERY bad soldering - it possible the mfg did that. It looks very unprofessional - but there is a point of overdoing it and as long as it works - thats the main thing. The old solder is difficult to heat and uses rock hard flux - yikes.

When I copied my ROMS - I had to figure out the Willem 5.5C settings for the 2732 Eproms. I made notes (as I always do) on this chip - so I dont have to figure it out next time- I can just refer to my own notes. The Willem is a good program - but it doesnt give all of the board settings. I had to figure it out and also voltage for the chip. I was glad to see that my ROMs for the Brazil ICT-101 tester are actually the Extended ROMs - this has about 26 additional chips above and beyond the standard. So, I would guess that the ROM version is 204. I dont have the greatly extended ROM 205. But even so - I am glad to have the 204 chiplist now. Every little bit helps. The version was printed on the sticker found on each of the chips - but due to the previous owner leaving it outside - the labels look tattered and unreadable. THe only art that is readable is 84. Inside the ROMs I found a date code of 1984. Also I can visually see a list of chips (viewing the BIN files using Notepad) including 74299, 74653, ... 74245 etc which confirms that yes I do have the 204 ROM chiplist.

Update 6/1/15
I removed the power supply and checked the components one-by-one using my Bk815 and caseless tester and Fluke mulimeter and Beckman Scopemate2. I was alarmed that the Scopemate2 showed a vertical line on all power supply  components - so I tested each one strategically removing it from the circuit. When I tested the parts out of circuit - it tested normally. Regarding the vertical line- I would say that it is just how the components are arranged that is causing that reading.

I found 2ea bad parts in the Power Supply

1ea SCR (2N6395 substitute NTE5552) which even my caseless tester cant identify. I tested it on my Mosfet tester and it gave a strange result - usually when I press the button - the red light comes on. ANd when I let got the red button - the LED turns off. Well it is opposite - always lit and when I press the button it turns off. It did look right to me so I have further tested it and looked it up in the book and eve my caseless tester doesnt know what to make of it. It is a bad part - and needs to be changed. The second bad part is a big heatsink transistor 2n3055 and I had a couple in stock. I suspect when I fixed my first ICT-101 I proabably ordered a few extras. One of my instock 2n3055 is bad (maybe was the one in there that I changed out?). The Brazil ICT-101 has a 2N3055 which tests 17 on Hfe gain but it has .08 leakage- and the replacement has 11 hfe gain and 00 leakage. Even though it looks brand new it could be a used one. Nonetheless - Id rather have one that has no leakage. So that is a bad part and needs to be changed out. Now it still is functional with a leakage - probably but I dont want to push my luck as it may weaken some other part. So it needs to be changed. Im glad I had one in stock.

Also I found a solder point which had a copper island which was detached from the PCB. I used epoxy and glued it back on. Then I scraped 1/4" of each side of the copper trace and soldered the bridge. Leftover hoopla from the previos owner's unsuccessful attempt to fix it. At this point I have not even attempted to plug it to AC power. I will go through everything first such as checking wiring of transformer - fixing SIL pins, checking chips etc.

I noticed that the power supply underside has a chart which indicates which pin is for 120V and 240v and 100v etc. So this powersupply is universal worldwide but it need to be wired a certain way. I will make sure it is wired the same way as my working ICT-101 unit. It apears that this one is set for 120V - so the previous owner must have run it on a voltage stepdown transformer. It is un-necessary because it is internally capable of any voltage conversion.

I have gone though 100% of the power supply and at this point know all the rest of the power supply parts test good.

Update 6/9/15
I received the Italy ICT-101 unit a few days ago- I left it for a few days due to the weather. I noticed that the box when tipped made a "clunk" sound and I knew that something inside the box was banging around. I disassembled the shell and found that the seller had unscrewed the transformer/power supply and was just banging around in there during shipping. Fortunately I got REALLY LUCKY that shippers were not rough on this box. Even though the outside of the box looked like an accordian - it didnt get tipped or jostled much. Nothing was broken - only a few wires were pulled from their crimp connector spade ends. I re-crimped the ends back on - reusing the old spade connectors. The only thing I found missing was a tiny washer - which I have plenty of nuts/bolts/screws/washers in my workshop. I spent a couple of hours cleaning mud off the ribbon cables and case and book. Heres another IC tester that spent some time outside in the mud. But I brushed ou the very minor debris - was in drastically much better condition than the last one. I ran out of daylight at 9pm and will have to finish cleaning the LCD front panel assembly another day. This Italy unit is a 240V. The Brazil unit was a 220V unit. I made careful photos of each one. It is unfrtunate that the 2 wires were disocnnected from the spade connectors on this Italy unit (blue and brown wire) and I will have to use my best judgement to decide Left or Right. I will base my decision on my 2 other ICT-101 units and hopefully that will be correct for this unit also.

I got cheated severely by the seller. But I can fix it. Isnt it terrible when people do that to buyers? I never do that kind of stuff to other people. The main thing is that the memory board is present and all boards are present. The ROMs have 204C sticker on it. It also came with the ground wire/clip end and 20-pin IC clip and ribbon cable. Almost every single part is common and replaceable on this tester. It is VERY serviceable wih just off-the-shelf parts. Im very pleased to have it. I even have a manual which is slightly different than my 1st units book. I now have 3 testers and 2 books. All of my units have zero rs-232 ports on the back. I am confident that I can change the 240V and 220V units to 120V. The newest manual has a diagram for voltage changes - but it doesnt show 120V. I have a REAL unit with 120V (that I repaireed) so I can just look off of that unit - and see how it was done. I got very lucky no boards were broken by the heavy transformer/powersupply banging around in there. There are some scraches on the board below the power supply. the top of the transformer has a very beaten up sticker (I straightened it as much as possible) and the model of the Italy transformer is the EXACT same as the Brazil transformer. They are idetical units. I feel that the Bazil ICT-101 is probably a very early model because the memory board is not green and the epoxy covering it is kind of rubbery or sticky. This newest Italy ICT-101 has identical looking memory board to my first unit. My hunch is they are all electrically exactly the same. I see the very same components on the power supply and boards. Same layout of parts. Same bodge wires under the board. This Italy ICT-101 has a MUCH BETTER soldering job than the other 2ea units. It looks nice and neat solder joints on the LCD front board/panel. I cant begin to tell you how awful the 2ea other units solder job looks. I didnt do that - it came that way. That solder it also doesnt want to melt at standard temps.

I see some crud in between the LCD panel/board so I will use an aircompressor to blow it clean tomorrow. I ran out of daylight so that will have to wait. I reassembled everything as it showld be - after cleaning and repairing wires and straightening the transformer sticker etc. I scrubbed all the muddy ribbon cables and the 2ea white plastic rectangle spacers that go below the transformer. It looks nice now. Why in the world do sellers cheat like that? After about 3 hours of work - I am very pleased with what I see. I got very very lucky- it could have been all in broken pieces. Yikes.

At this time I have 2ea ICT-101 on my workbench open. The Brazil unit I am not done with figuring out which parts I need to order. With the Italy unit Im hoping that it will power up after I change the AC cord to a USA 125V cord (I will use a PC AC cord with the end cut off) The seller sent me photos showing the unit powered on. I hope that was a real and legitimate photo of this unit powered on.

There is no way I coul;d have plugged in this unit without extensive work for 3 hours. The screws were wedged under the bottom circuit board, wires disconnected, transformer not mounted. If I would have plugged it into my 220V transformer I would have blown boards, powersupply, and my step-up transformer. I wasnt going to risk anything by trying - Im not a gambler - I dont take chances. I decided to disassemble the unit completely and do what I did to make sure it is clean ad properly assembled - with nothing out of place or missing. It is no longer a disasster mess. It now looks very good.

Update 6/14/15
I spent about 1-1/12 hours cleaning up the front panel with about 15 q-tips ear swabs and green cleaner (saved some from the cleaning tub and filtered it with several coffee filter for reuse) The panel is nice and clean and I thoroughly cleaned the ribbon cable and in between the front panel and the circuit board and all over. As I was carefully and slowly prying off the 20-pin connector which goes to he front of the panel - 2 pins got bent/ It was slightly rusty in there and didnt come out smoothly. When I tried to carefully straighten the pins - they both snapped off. The metal was brittle (I can tell this tester spent some time outside and probably caused the metal to corrode/degrade). I spent a good hour or more trying to locate a replacement 20-pin connector. I tried big-auction site and some sellers wanted big money for this type of connector $13-26 each and not even the right pin count. I went to DIgikey website and found 3M and AMP and several other brands from between 1.60 to $3.10 each and some gold plated - I bought that gold plated one. It was a lucky find because you have to use the right wording. I ordered Digikey part number 1-746611-0-ND and with US Post Office First Class mail shipping - my total came out to about $7. I was lucky to find a good substitute. The moral to the story is that this ribbon cable should not be removed - it is prone to get broken. One that ribbon cable and 20-pin connector are installed - leave it there. When it arrives - I will snip off about 1/2" of ribbon cable from the end and then install the new 20-pin replecement connector. Some sellers call it a Header, IC connector, DIP, AU DIP, Conn, 20 POS, 20-pin, 2x10, .100 x .300 All kinds of copmbinations of these wordings. It seems that all vendors refer to this type of connector - in a drastically different way. I will need another one - to buil a cable for my third unit. But for now I just ordered one.


Update 6/15/15

I tested a brand new NTE5552 which I bought to replace a 2N6395 SCR and I found that the new part gives the same strange Lissajous pattern vertical line. Also my SCR tester gives the same LED lit then when the button is pressed the LED goes out for as long as the button is pressed on the tester. This LED response on the tester is opposite of normal. I made an error in thinking that the original part is blown - when in fact the 2N6395 wasnt blown. SO I ordered a $6 replecement part for no reason. It happens to the best of us- I try to keep the misordered parts to a minimum. I put the new part back in its package and will save it in my inventory. So I would consider the power supply fixed at this point. I thought 2 parts were bad but in fact only one was bad/weak which was a 2N3055 which I had in my inventory which replaced a .08 leakage part with a 00 leakage part. Power supply repair is now done. I need to rewire the transformer from international voltage to 125V AC US standard.

I usually make a detailed notes sheet when I am fixing something. I put the pinouts, measured values, notes etc. I will include the scanned notes pages here which shows my diagnostics on all the components on the ICT-101 power supply.

ICT-101 Brazil powersupply repair 1.jpg ICT-101 Brazil powersupply repair 1.jpg
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ICT-101 Brazil powersupply repair 2.jpg ICT-101 Brazil powersupply repair 2.jpg
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Update 6/16/15
I spent quite a few hours late-night converting the Italy and Brazil ICT-101 units to run on 120V AC USA. I am fully done with one unit's power supply. It has a PC power cord which I found in my inventory parts and cords etc. Actually Im very surprised to find an exact match for the cord - it has the very same 120V plug in every detail. I measured the length and cut down a PC cord so it is EXACTLY the same length as my first unit wjhich came with a factory installed cord.

When I powered up the Italy ICT-101 - I noticed that the self-test did not comnplete fully. It gives a error message "Interface Bad" I can clear this error by pressing reset and then the menus respond normally. I do not have my ribbon cable connector so I cannt test an actual chip to see if the tester performs fully. The error may mean that a component on the boards is bad. The power Supply provides 4.63V at the rear red/black connectors. My working unit gives 4.75V which is probably close-enough. I feel that the power supply is OK now.

I used the opportunity of a semi-working unit - to test the display board from the Brazil unit - which is not as far along. The display is a 16character 5x7 dot matrix alpha numberic LCD. It uses Hughes H0551 and H0550 ICs which are proprietary. I see that the Brazil LCD display shows the first 2 characters properly. The third character is 50 percent working and the remaining 13 characters are not working properly.

I looked at the solder joints and they are horrible and tnkered with by the previous owner. I compared the display panel boards by Lissajous pattern and found that all three display drivers are bad. The working display panel has a zig-zag lissajous pattern on all pins. On the partially working display panel assembly - most pins show a zig-zag lissajous pattern but some show a L shaped lissajous pattern or some are unresponsive. The solder joints are just horrible and just barely connecting. Due to the sensitive nature of soldering onto LCD glass panels - I cant just solder all of the connections- too risky. So I made a mark next to all pins which dont respond normally - next to all connections on the display panel solder joints. I will resolder only those joints and it may have a beneficial effect on the number of characters displayed. But still there are definite drastic differences when I compare lissajous pattern of the working/partially working - so there is a definite problem within the display driver ICs.

Brazil ICT-101 faulty display A.JPG Brazil ICT-101 faulty display A.JPG
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Brazil ICT-101 Faullty Display B.JPG Brazil ICT-101 Faullty Display B.JPG
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Brazil ICT-101 Faulty DIsplay C.JPG Brazil ICT-101 Faulty DIsplay C.JPG
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Brazil ICT-101 Faulty DIsplay D.JPG Brazil ICT-101 Faulty DIsplay D.JPG
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Brazil ICT-101 Faulty DIsplay E.JPG Brazil ICT-101 Faulty DIsplay E.JPG
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I made some notes on the transformer wiring for the 120V 220V and 240V configurations. The underside of the power supply shows a chart for configuring the jumpers and output lines for various voltages.

Update 6/21/15
I finished repair of the Brazil ICT-101 and is now fully functional. I did some extensive testing with it and side-by-side comparisons with my USA ICT-101 and now works and looks equally well. I have moved the Italy ICT-101 display panel assembly over to the Brazil tester in order to complete it. I feel very tired and very glad to have a second unit as a spare.

I spent the last few days doing work including the removal of 2 chips on the mainboard of the Italy ICT-101 which gives a strange "interface bad" error at the conclusion of self-diagostics test. I have socketed 2 chips after carefully removing the ICs. I have put back the same ICs into their sockets and get the same results as before. Since I have a massive quantity of 7400 chips purchased from a local shop about 10 years ago which closed- I decided to go through one of these boxes and sort the chips using styrofoam sheets as a temporary holding area- I then moved these sorted chips into their components cases. I am about 1/2 done with this sorting process - I estimate 2 thousand chips or more per box. I have definitely found in-stock replacements for the socketed chips. It is interesting that my out-of-circuit IC testers test the socket chips as being good- but my ICT-101 units - they sense some flakiness in these chips while powered on in-circuit. Sometimes these chips are misidentified and sometimes identified properly. WHen comparing a workiong mainboard - the ICT-101 identified these same chips easily and quickly. This tells me that the socketed ICs are bad and the 2 adjacent chips are suspect also.

I also spent some time researching replacemet IC chips made by Hughes and see in their "1984 Hughes CMOS Databook" found online as a pdf file - I see that the 0551 and 0552 are LCD drivers and I searched for replacements looking through many pdf files and online datasheets. I found no substitute for this IC - it is very unique and sophisticated - very much like a ascii terminal on a chip. I see that it is a hard to find chip. I have requested an online quote from an online source which states that they have a few in stock. The hunch that I am making is that the "HC0550-0-P-000" and "HC0551-0-P-000" is the same chip but just has a different part number. The original part number on my board doesnt pull up any results online. After much research and trying various searches for incomplete part numbers and then verifying pinouts and descriptions. It is my hunch that this is a match for the chips I need. I hope my hunch is correct and that the price quote isnt astronomical. Here are some photos of my display board assembly's PCB showing the 3ea chips which test bad and this LCD board only display the first few characters- the rest are just black all-on characters. The Lissajous patterns on these ICs shows me all 3ea ICs have internal issues and shorts on several legs.

My hunches after doing much research and checking online information as best I could
1. Hughes HLCD0551 Intelligent Display Driver (Main) = Hughes HC0551-0-P-000 or HC05510P000 Column Driver (1ea needed)
2. Hughes HLCD0550 Intelligent Display Driver (Peripheral) = Hughes HC0550-0-P-000 or HC05500P000 Column Driver (2ea needed)

I hope that my hunches are correct, and I hope that these chips are available for purchase at a non-skyhigh price.

ICT-101 Brazil display board closeup ics.JPG ICT-101 Brazil display board closeup ics.JPG
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Update 7/17/15
I ordered these ICs a couple of days ago. Today the seller emailed me that it is shipped. I hope my research and professional hunch is correct- about these chips being a correct replacement. $100US is alot of money to spend on 3ea chips. This seller was a reasonable seller and accepted my lower offer from $38 to $30each. This was a real bargain compared to other "unreasonably priced sellers" who sent me quotes of $600+ These chips are discontinued and the last known price was approx $15each as of about 10 years ago. I gladly paid double their value. But the Jotrin has a reasonable price and I felt the IC tester was worth it and I'm taking a gamble on my professional hunch that these replacement ICs are the correct ones. I hope so.

Jotron Electronic Limited (Very reasonable price and prompt emails etc)
HC0550-0-P-000 HUGHES DIP40  1ea $30US ea
HC0551-0-P-000 Hughes DIP40  2ea $30US ea
$10US Economy Hong Kong Shipping 2-5 weeks

Update 7/25/15
I received the 3ea ICs from Jotrin yesterday and I have not tested them. I need to purchase 3ea 40-pin low-profile IC sockets still. Here is a photo of the Jotrin items.
Jotrin 3ea ICs for ICT-101.JPG Jotrin 3ea ICs for ICT-101.JPG
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Micro Concepts BoardWalker 103

This is a digital IC tester which can test in-circuit (using lefthand zif socket on front panel) and out-of-circuit using a ribbon cable with IC clip - attached to blue connector on right side front panel "Test Clip" My unit was purchased 9/2016 used and was missing the ribbon cable and manual. This unit is model 103 and has Version 2.0 software and shows 1991 mfg year on LCD. Backlit EL (Electro Lumen) display (Blue-ish Green-ish Backlight). According to my research, I believe that this was the last revison/model of this series of testers. Im glad to have another in-circuit tester which makes my life easier when repairing damaged or non-working vintage boards - it means that I dont have to desolder the IC before testing (as often - desoldering is still required for stubborn issues with some repairs)

Very Large - about the size of a desktop PC case. Has a carry handle which serves as a "foot" when swiveled down. I repaired this unit (see my repair notes for details)

In-circuit testing, out-of-circuit testing, Search function (identifies unmarked or house-branded chips), Probe Function, Logic Monitor Function


I have not yet created a chiplist for this unit. I am able to scroll through the menu to see all of the testable ICs. I have the standard ROM built-in. I do not have the extended plug-in ROM which goes in the front panel lefthand IC socket.

Update 11/15/16
I received 5ea 34-pin IDC connectors today from international seller. I immediately got to work crimping the connector onto my existing 16-pin ribbon cable with IC Test Clip. I made the mistake of plugging in the new connector into the Boardwalkers 34-pin socket which was missing the 2ea blue side levers. After plugging it in - I pulled on it carefully from each end trying to unplug it- and the connector's snaps broke. Since I ordered 5ea, I had 4 spares - no problem. I redid the connector and shortened the cable with a pair of scissors to get rid of the marks/piercings of my previous attempt.

This time, I scavenged 2ea blue IDC connector levers from a bunch of high end equipment which I am working on (Rank Cintel ADS2) and I have alot of spare parts for. Th blue levers are not a perfect fit - a different brand of connectors - but works good enough where the levers can safely unplug the IDC connector from the socket.

I have included 4 photos "Boardwalker IC test Clip A,B,C,D"

I powered up the IC tester and went thorugh the menus but shut it down since I just dont have a manual for how to in-circuit test ICs. I didnt want to risk damage to the tester or circuit- without a manual possibly doing something wrong.

My BoardWalker 103 repair notes 100516.txt My BoardWalker 103 repair notes 100516.txt
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BoardWalker103 Passed Loose Pic A.JPG BoardWalker103 Passed Loose Pic A.JPG
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BoardWalker103 Passed Loose Pic B.JPG BoardWalker103 Passed Loose Pic B.JPG
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Boardwalker Test Clip A.JPG Boardwalker Test Clip A.JPG
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Boardwalker Test Clip B.JPG Boardwalker Test Clip B.JPG
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Boardwalker Test Clip C.JPG Boardwalker Test Clip C.JPG
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Boardwalker Test Clip D.JPG Boardwalker Test Clip D.JPG
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Micro Concepts Boardwalker 101

TTL digital IC tester for use with out-of-circuit and in-circuit testing.

Purchased used 4/24/17 from online seller auction site in untested condition. The date of Mfg estimated 1987 (manual date 1987). The case is grey and front panel and rear panel are a darker grey color. Buttons on the front are membrane style (like a microwave oven) The LCD is 16 characters x 2 rows dot matrix style letters and numbers- with no backlight. It came with quite a few test clip ribbon cables - only one of which looks original. Im glad to have the multitude of 24-pin, 40-pin, 20-pin cables - some of which have IDC connector and others have DIP IC style connector. Some have shrink tube attachment of IC test clip. Possibly some of these cables were made by the previous owner. Included was the original manual (about 3/4" thick) and a white AC cable with a right angle PC style detachable power cord (not sure if that is the original power cord but works good)

Missing one square rubber foot (I may have one just like it in my inventory- it looks like alot of contact cement was applied - may have been attempted to fix by the previous owner?) and missing swivel handle/stand - the 2ea attachment points for this handle are present. The box had a rough journey and very very low amount of styrofoam (only 2 pieces) so the tester arrived with broken 26-pin (13-pin x 2 rows) IDC connector on the units face (I will replace it at some point in the future) and most of the test clip cables arrived with bent pins (will try to carefully straighten without breaking off the pins)

ROM version is 2.0 (probably the latest version for this model) and I successfully tested one 74373 IC (pin one is facing up when inserted into IC socket) which completely covers the right-most IC socket (this socket is for skinny ICs up to 20-pins) I was amazed that it powered up and gave a normal looking LCD display (how many times have I received a used item and it worked fine?). There is no backlight. I skimmed through the manual and it said that the Pin Selector Switch is required before testing an IC. I scrolled through the chiplist (Long List) and found 74373 and moved the VERY LOOSE almost broken Pin Selector Switch to 20-pin setting. Then I pressed GO - didnt work (said no ground detected) and I tried the select button and got more errors "VCC and GND dont match"

I made the correct assumption that the loose wiggly pin-selector slide switch was the culprit. I pushed it in slightly and then proceeded to test properly. "74373 PASSED" and I photographed it (see photo)

So the basic function of the tester is in working condition- but pin-selector switch is in bad shape.

The BEST feature of this tester which is In-Circuit IC testing ( some people call it "backdriving" ) has not been tested yet.

As I have an opportunity to read the manual and improve the loose/wiggly pin-selector switch and other repairs, I will update this description.

There are 3ea IC ZIF sockets on the front panel. The left is for External Library ROM chip (I dont have that Extended ROM- the manual shows loading the software "E Z Walker" on 5-1/4" floppy diskette and PC to develop custom ROMs.) and the Middle Zero Insertion Force (ZIF) IC socket is for WIDE chips. The right-most IC socket is for narrow/skinny IC chips up to 20-pins.

It appears that when testing a loose/unsoldered IC chip the pin-selector needs to be moved to the right - to select the correct number of IC pins 14, 16, 20 ... But when testing a soldered chip mounted permanently on a PCB circuit board - then this pin selector switch needs to be moved left-most to the "OFF" position. This pin selector switch is not a power on/off switch - but it does select where the IC chip under test is located - in the zif socket or soldered onto a board and linked to the Boardwalker 101 by ribbon cable with IC test clip.

Unfortunately my pin selector switch has a drastically bad feel and wiggles and wobbles - it has a hacksaw blade feel when moving it left and right. It is possible it was damaged in shipping - its too bad that there was insufficient packing material as I paid extra and requested it and even offered to pay more etc and explained that ... Whats done is done. Now I have to focus on its repair.

I see a 25-pin connector on the backside - I dont know the purpose of that connector yet Most likely it is the way to connect to a PC using E Z Walker software (I have emailed seller to see if she has missing handle and 2ea missing diskettes)

The manual explains "Boardwalking" as a custom ROM test sequence made by the user - in which an entire board can be tested IC chip to next IC chip to next IC chip ... in the users custom sequence contained in the user created ROM. Boardwalking (to the best of my understanding after reading the manual sections) means being able to test every chip on an entire board. It further explains that the user can create a new ROM for every different board. Thus making a unique ROM for each and every unique board- this saves time in scrolling through the chiplist- and also allows custom chips to be tested that are not on the chiplist. I dont have this software to do this - but this "holy grail" description and screenshots are in the Boardwalker 101 manual. I have previously heard of this feature on other testers - and never found anything substantial to backup this online "rumor" - with other brands/models of testers. BUT HERE IN THE MANUAL for Boardwalker 101 I see that for this tester there actually WAS a way to custom make these ROMS.

The manual is one of the best Ive ever seen. Exploded view diagrams, extensive cross reference of Generic ICs, namebrand ICs, military ICs, schematics, long detailed descriptions of functions. Also a chip by chip explanation of how the machine works. This book is like an encyclopedia for the expert and sections for the novice/casual user.

Also the tester has a "logic probe function" but that term denotes one pin testing - whereas this machine has "logic monitor"  (an industry standard term) that is a more fitting term as it shows all pins on an IC simultaneous. I havent tested this function yet. This tester has logic monitor function - yet understates it by referring to it as logic probe. Pen-style Logic probes can be used on a LIVE OSCILLATING CIRCUIT but the Boardwalker 101 is NOT FOR LIVE OSCILLATING CIRCUITS so Im not going to use that function or even try it. I have a normal standalone logic monitor (see photo of LM-2A elsewhere on this page) which I can use for live circuits.

Some quirks in version 2.0 ROM

The arrow up button scrolls down numerically in the internal chiplist.
(This appears to be correct as the book describes the down arrow as moving forwards in the chiplist)
The arrow down button scrolls up numerically in the internal chiplist.
(This appears to be correct as the book describes the up arrow as moving backwards in the chiplist)

The cross reference section of the book showing military, name brand, generic ICs - the manual has some similarities to the manual for the Micro Sciences ICT-101 tester. This artificially makes the chiplist longer as mfg variants of the 7400, RAM and Eprom, 4000, 9000 series chips part numbers is long - whereas the generic list of chips is much shorter without redundancies.However some mfgs make their part numbers "far out" and unrecognizeable as ordinary standard 7400 series for example. The elaborate cross reference is both redundant BUT useful in those rediculously marked yet cross-reference-able to generic standard IC.

Super great manual with nice drawings and illustrations etc. Couldnt be better. I hope when I delve deep into programming a ROM (assuming I can acquire the software) Is the manual going to leave me scratching my head or will it be thorough - we'll see.

As I compare the Micro Concepts Boardwalker model 103 to the model 101 - I see a huge size difference and the newer of the two being much larger. Also I see the same connector on the back with missing metal surround shield on the connector - so that makes me think - it is supposed to be that way. The basic LCD navigation of menu "feel" is similar- I am missing the Board Walker 103 manual so by reading the 101 manual - I may learn about the basic function of both units - possibly the custom ROM creation is the same on both units? Who knows?

As the front IDC connector arrived broken - I taped the 2ea pieces to the top of the case (see photo) so they wont get lost. It got broken as the Boardwalker 101 tumbled around during shipping in a large box with almost no packing material. Im lucky to have had as little damage- it could have arrived in much worse condition.

There is a paper sticker on the front face panel that is very worn and almost illegible - it probably warns the user to connect the clip under certain power-up sequence. I will read the manual and try to figure out what the sticker says.

There is some damage to rightmost ZIF socket where it looks like a soldering iron was touched on the plastic. This test socket still moves well and tests IC well. I will leave it alone. "If it aint broken dont fix it."

The case is exactly the same dimensions as the MSI ICT-101 and I received emails from a software engineer who worked at both companies and was told that there were people who worked at both firms. This explains the similarities between units.

Let me know if you have a replacement multi-position slide switch for this (off plus 6 additional detent/click positions so that means 7 total detents slide switch). I have the little black cap that goes over the little switch's lever.

Clear plastic tape Sticker #1 Reads IN UPPER CASE BLUE LETTERS

White square paper with red letters Sticker #2 Reads
"WARNING! Before connecting test clip, remove all ICs from front panel and place pin select switch to off position. Damage may result."

Version 101A is special

On the front panel it shows model 101. But the rear panel metal plate shows model 101A.

As I read the manual, there is a section in the back for model 101A which shows "E Z Walker" or "EZ Walker" software which is used to custom progam a library ROM which can then be used on any 101 or 101A. WOW Im looking at a machine that can do this. As I contacted the seller - she threw out a box of diskettes 3 weeks ago - and she is looking to see if an old PC has this software installed.

If anyone has the "EZ Walker" software (book shows ver 1.00 but any version is fine) for any of the Boardwalker series - Let me know. It is possible that both of my units models 101 and 103 can make these custom library ROMs?????
Boardwalker 101 received 042417 Rear  Panel.JPG Boardwalker 101 received 042417 Rear Panel.JPG
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Photo of Boardwalker 101 Manual.JPG Photo of Boardwalker 101 Manual.JPG
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Lots of bent pins.JPG Lots of bent pins.JPG
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This is a Portable Linear IC Tester LIC and is a handheld tester. It is my only linear IC tester at this time and my 8th IC tester. It has the same shape and style case as another one of my testers. I'm glad to have purchased this tester as I was looking for a used one for a long time. This unit came with the original AC power adapter which is 9VDC 500ma or can run on 2ea standard 9Volt batteries. Several companies sell this tester under various name brands. I have listed the chips it can test at the bottom of this page on the right-hand side in grey color. This tester was purchased from a Canada Seller on 11/13 and shipped to USA. Purchased (New Old Stock NOS and never used by previous owner) in 2013. Manufacture date estimated 2010 (this is a currently available item as I am writing in 2013).

The label is clearly marked for chip and semiconductor orientation of inserting in the socket. The Power Off procedure is not clearly marked on the unit. Here is how to turn off unit (Hold Down "Type" button while pressing "Down Arrow" Button) I know this only because I have a "sister" unit very simiar (see GUT tester on this page above) which has it clearly marked on the label.

This tester has helped me numerous times in testing voltage regulators such as 7805 etc and ICs which are analog such as the LM series and many others. The chiplist is very strange in that you have to scroll through all of them and just in random order. They didnt even put similar semiconductors next to each other in the internal chiplist. There is alot of scrolling and hunting until you find that in the very long chiplist - but once you find it by scrolling through the chiplist - it does test the component very well. I am very careful about making sure the proper chiplist component is selected - for the correct semiconductor component to be tested. I am VERY GLAD to have it. It has saved me alot of un-necessary replacing of suspect parts.

This Tester was purchased brand new NOS from a Canada Seller in 12/2013. This is my IC Tester #8

One thing I realized after I bought these test clips is that they have a "nail" head and - that part I knew by looking at the photos- But what I didnt realize is that one side of the row of nails is much shorter than the other side (not obvious when you look at the photo below). This is how they come from the MFG. So really after much searching for a clip on connector to make this detachable - i have come to the conclusion that I needed to solder onto these as a connector would work only on the long nail side but a connector would not reach the individual nails on the short side. Some of my connectors had the nail head chopped off (previous owner) which can be done with a Dremel rotary tool and cutoff wheel. I put heat shrink tubing on every soldered connection. I purchased a pkg of 10ea 26pin 2x13 IDC connectors as a lot and crimped this on the ribbon cable. Remember even though the test clip is 24-pin and the BK560 ZIF socket is 24-pin - the header is 26-pin- so it required a 2x13 IDC connector to plug into the header correctly (the bottom 2 pins are ground on the idc header).

Above pictured is a B&K Precision model 560 (sometimes referred to as a BK560) Digital IC Tester. It has a 24-pin ZIF socket for inserting chips for out-of-circuit testing. It has an IDC header for connecting an external clip of various pinouts. This is my second tester which can perform out-of-circuit testing. Soldered in chips can be tested without desoldering in most cases. There are times when the chip must be de-soldered from the board before testing. Since I purchased this machine used -it came with no ribbon cable clips so I made my own set of 5ea clips 14-pin, 16-pin, 20pin, 24-pin and a 20-pin microclip for SMD chips (I see quite a few 7400 series chips which are SMD nowadays so this miniature clip is necessary to test the SMD mini IC chips of the various chip families) This tester also has the ability to learn an unknown digital chip's truth table and store that data into memory chip storage for future comparison (see 4ea empty IC ZIF sockets one of which has a data storage chip installed). The list of chips is very long and I will add this chip list in the future at the bottom of this page in turqouise color and right-hand side as my time permits. This is my 9th IC Tester. I will add a photo of my self-made clips at a later date. For in-circuit testing using the external ribbn cable clip- the circuit must be powered-on but not in-progress. By not-in-progress I mean that the circuit must not be running or operating - but it must be receiving power. To further clarify - The crystal oscillating the circuit must be disabled so that the circuit is not underway or in-progress. The crystal oscilator must be removed. For eaxample when I test diskette drives - I connect the 5-1/4" disk drive to a PC power supply but the drive itself is not connected to the controller card. This in essence removes the crystal oscillations and satisfies the requirement that the circuit under test is not in-progress. The tester tests chips which are at a standstill and are not processing any data etc. This is my second in-circuit tester and the same not-in-progress requirement is found in my other tester for in-circuit testing.


I am looking for the decorative plastic cover which fits over the Eprom sockets. Either a black one or white one would work. Mine is missing this cover - the factory image shows with the cover and my own photo shows without cover (purchased w/o cover)

I am searching for the rare software option for this tester. The software named "AK560" or possibly a different name - will allow a vintage PC to connect to the back of the 560 IC Tester through the RS232 serial port. The software allows creation of customized IC test program - for chips not in its internal chiplist. I wonder if anyone reading this has a floppy disk (5.25" ? 3-1/2" or CD-ROM) with this vintage software which I am seeking?

This tester was purchased from a USA Seller on 12/13. This is my IC Tester #9

Update 6/22/15

I ordered 1ea 12" x 12" x 3/32" (.093") sheet of black ABS Textured and 1ea sheet 12" x 12" x 1/16" (.060") These sheets were purchased from big-auction-site and cost was approx $15 for both including shipping. Using my laser engraver, I will do my best to make a replacement cover for this IC tester - then glue those pieces together with Weld-On #3 which is a plastic solvent and fuses the material together. I was not able to find an original replacement after years of searching. I will fabricate my own. I plan on using these sheets for several projects including making a back panel for my semiconductor analyzer/battery pack (see PST-5000 further up on this page). If I cut carefully - this material should be/may be enough for both projects. Another alternative is a 3d Printed part - I do not own one at this time (I will buy one sometime in the future when prices come down). The ABS textured sheet cut/fabricate/glue will give a more accurate glossy testured finish which more closely resembles the original.

Update 11/18/15

I drew the following 4ea illustrations (using Microsoft Paint) of making your own Test Clip Ribbon Cable for use with B&K Precision model 560 IC tester. These diagrams show the 1:1 correlation between the IDC male connector and the IC under test. For example the top 2 pins of the IDC connector correspond to the top 2 pins on the IC being tested. 

Whether you choose to make a professional cable using real parts like IDC 26-pin female or ust makeshift jerry-rigged amateur wiring is up to you. I suggest making a good-looking cable that is professional looking. I purchased my IDC connector, and misc items, and my IC clips on big-auction-site.

Update 9/3/16

I purchased an original BK 560 manual from big-auction-site and posted a photo of this blue cover manual here. 

Here are a few photos/drawings.

BK560 owners manual Pic.jpg BK560 owners manual Pic.jpg
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The above pictured Berkeley 998  is a Linear IC tester and is a vintage analog piece of equipment (estimated 1965 to 1975 estimated mfg year). I purchased the manual and tester from different sellers. I feel fortunate to own it as it is rare. I plan on testing op amps and voltage comparators. To be honest the manual only gives one example on how to use it and I need help on understanding how to use this tester. All of my other testers are simple to use and operate. This vintage linear IC tester is very capable machine but I need to learn and am going through the book but I can see that the book's one example is insufficient. I am also going through the internals to test components one-by-one as this is a used item purchased recently - to make sure it functions.  Ideally someone will share their notebook notes on step-by-step how to test alot of chips with this tester. The title of the manual I have is "Model 998 Linear IC Tester Instruction Manual" and has schematics / parts list at the end. At the present time I am unfamiliar with how to use this tester. I look forward to using this equipment as it will tell me the linear/analog values rather than just pass/fail. This will help me assess the condition of chips so I can make the decision to replace if readout is weak.

Somethings that are not clear - use of oscilloscope in conjunction with tester? Slider sellings. Use of knobs and switches and dials. I have the 16-pin socket and the book says there are various 14, 16 pin sockets available- I would like to acquire those additional sockets.

Any help or insights on how to use are appreciated. I would like to know step-by-step how to test LM310 and LM311. I hope a kind reader will educate me on how to use this well-made machine (through email or video?). My email address is in case a kind soul will share their insights on how to test.

It is possible there exists a manual (I dont have that) that shows settings for various chips and semiconductors. I do not have any list or settings for various ics at all - only the very thorough (only 1 example in the book) example of testing Fairchild 709 which is quite hard to follow and understand. I purchased this tester in 12/2013 from a USA seller. The testing procedure is from a different era and I am having trouble grasping the concept. It is probably very easy but I am missing these necessary insights.

This IC Tester was purchased used from a USA Seller in 12/2013.  This is my IC Tester #10

Update 12/2013 I have ordered a NTE909D IC which is sealed in its original plastic bag - never used. I will use that 14-pin IC to go through the book's instructions for testing 8-pin 709 Op Amp. Due to the 14-pin rather than 8-pinout I will need to figure out which pin and slider switch needs to be used for this IC for proper testing. I noticed many other sellers of 709 chip or can package ic - the prices are skyhigh. I instead ordered this chip from RadioShack online for $3.60 w/free shipping and is a cross reference for the 709 Op Amp 14-pin edition and is a real bargain pricewise compared to sellers of other brands of 709 Op Amp. I will need to figure out the pin settings and make notes on the side of my book page - so I use the proper pinouts for the 14-pin chip.

ABI Digital IC Tester Chip Master Compact

This tester was purchased used and was mfg in United Kingdom on 2005 and has ROM version 2.00 which is the most current version for this model. It runs on 6V DC at 300ma (I disagree with this voltage as I think it is not correct- I think that the TVS was either 5v or 6V as my best hunch so connecting 9v would blow it out - which is most likely what happened to the previous owner. Some chips on this board have a max rated capacitor of 6V) by using an AC Adapter  (I do not have this) or with standard 4ea AA alkaline batteries. This model of tester is rebranded/branded under at least 1 other namebrand. Some models have a rs-232 port built-in which allows for user added chips and are considered the "Professional" series due to the ability for users to program their own test routines for unknown chips. My tester does not have this rs-232 port and I will use the built-in chiplist only. I see a downloadable firmware update on the ABI website for this model. I will check the firmware version and update it if needed. Hand-typed chiplist is shown in orange color on the right hand side "ChipMaster" I see some similar models advertized as being IC Tester / Identifier which refers to its ability to search for many but not all IC chips inserted in its ZIF socket. This is my IC Tester #11

I purchased this tester used 12/13 but the seller sent a non-working tester - the following files show how I got it to power up it and now works. Maybe it will help someone with a similar issue. I suggest only running this tester on batteries or its original power adapter. Do not use any ordinary AC power adapter - that is what the previous owner did and it blew out the tester. It now works well after repair. I may someday add a 5v internal voltage regulator - but for now it is un-modified except for the removal of the blown 5v or 6v bilateral/non-polarized TVS surface mount component (my best guess at what it was) which was causing a 390ohm short across the supplied power input. For now I am using it only on batteries - until I locate a replacement SMD part and possibly modify it later-on with a voltage regulator.

Update 12/15/14

I believe that fuses and TVS are both protection devices but TVS responds substantially quicker in nanoseconds rather than fraction of a second. TVS is much more INTOLERANT of too high voltages or surges or even micro second interuptions in power. When the TVS blows it is not an OPEN. It is a high resistance ( 390ohms in my case) short between the + and - Fuses are INLINE with the power. TVS is placed across the power. If a fuse blows - it opens and does not allow power to reach circuit, If TVS blows - it creates a high resisitance short - if the power source is not removed - the TVS heats up substantially getting hotter and hotter and hotter and in my case - I found a charred black board. Why didnt they use a voltage regulator such as 7905 or 7805 ? Possibly for power consumption reasons they chose to do it this way- putting the voltage regulator inside the AC power adapter rather than inside the tester? I dont have the AC adapter.

Update 12/15/14 (continued)

I caution you to NEVER connect an ordinary ac/dc adapter to this unit. It is my opinion that the part that was found to be blown on my own used unit - that part is a protection device with a very small tolerance for deviance in supplied power. It is intended to blow this part - if a non-specified power supply is connected.

Heed my advice and only use batteries. It is my hunch that should the original power supply go bad - this can also happen. Play it safe and use batteries on this tester.

How I fixed my ABI ChipMaster 010114.txt How I fixed my ABI ChipMaster 010114.txt
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Update 12/14/14

I see a video on youtube where a man is using a B&K Precision handheld IC tester (probably model 575 or 575A as my best guess) for determining whether a large quantity of Z80 chips are good. He inserts one after another after another and they all display "FAIL" on the screen. B&K Precision IC tester and ABI Chipmaster are "sister" IC testers which look similar and function alike. It is my opinion that the author of this video (not me) has entered the incorrect Z80 type into the tester - and therefore is getting "FAIL" - but in actuality - it is my hunch that this is a USER ERROR. Refer to my chiplist and notes at the bottom of this page - for example Z80 chip type can be one of the following:
Z80 Chips
Z80 CPU   (Use 780)
Z80 CPU  (Use 8400)
Z80 PIO (Use 8420)
Z80 CTC (Use 8430)
Z80 SIO (Use 8440)
Z80 SIO-2 (Use 8442)
Z80 DART (Use 8470)
Entering the wrong number ( I put this in parenthesis ) for example and then inserting a different type of Z80 will give a FAIL when in fact it is just user error. It is VERY possible that he has a whole bunch of BAD chips - however it may be just that the wrong number was typed in before testing these Z80s.

Search for "Z80 Tester" on youtube to see the video. It is not my video.

The technical specifications of the B&K Precision 575A (white case) and the ABI Chipmaster (black case) look to be identical in their chiplist and PDF manuals. These are "sister" testers.

Update 4/18/15
I contacted a kind person who posted a for sale ad for 1ea Chipmaster and 1ea Linearmaster. In his ad - he mentioned that he is using an aftermarket power adapter - and he showed that both testers work. I thought to myself - that is a very risky thing to do - hooking up a power adapter when the output of aftermarket power supplies can vary substantially- and yet the used ABI chipmaster (older model verson 2.00 rom without RS-232 port) that I have - came with a burned out TVS diode - probably caused by the previous owner hooking up an aftermarket power supply and exceeding the TVS diode rating.

So I contacted the seller and asked him to take his power adapter and measure the voltage output both for the Linearmaster and also the Chipmaster.

Here is what that kind person wrote (he has the older models without the RS232 ports - just like mine)

Power supply output without load (on air, no connection to the instrument) 13VDC maximum.
Connected with load 11 - 12 Vdc, depented on chip load (sigle test, loop....).

METEX M3610D with PC interface, 0,5% accuracy as long as I remember.

Chipmaster Tester: Output supply WITHOUT load (on air) 7VDC maximum. With load, 5 - 6 VDC. It varies depending on the load (big chips in loop, higher load in mA).

This tells me that the testers have a wider input voltage tolerance than I expected. The TVs diode inside will allow about 1 volt overvoltage (at least possibly more but - if you put in more than that - you risk blowing out your IC tester)

Keep in mind that the person used a RMS multimeter - and since RMS meters give a slightly different reading than a regular meter- that reading may actually be just right or off a tad. I suspect that RMS was the ideal meter to use. My understanding of RMS is that it measure the peak voltage - I could be mistaken about that. SInce TVS diode respond in a nanosecond or thereabouts - showing the peak voltage is ideal because there is always ripple - no matter how clean the power supply output is.

That tells me I need to look for a TVS (surge suppressor diode in surface mount chip package SMD) diode which is 6.8V or 7V maximum in order to replace it. Otherwise I will just put in a voltage regulator such as 7806 or 7906 which regulates the power to 6.0 or 6.1 volts from experience. I appreciate the help from this person - it helped alot - I sent a couple bucks as a thankyou for taking the time to help with this matter.

Littelfuse SMAJ6.5A = 6.5V 3.3watts max
Littelfuse SMAJ7.0A = 7v unknown watts max
Littelfuse SMAJ12A = 12v unknown watts max
Littelfuse SMAJ13A =13v unknwn watts max

I searched on big-auction-site for "6.5v" or whatever voltage "TVS" "Diode" Surge" Suppressor" in various combinations. This resulted in quite a variety. According to the 300ma power requirements this would mean a 3watt TVS is needed. Many of these are listed as 400w or 500w or 600w or 1.5kw. I think that is way too high. The Littlefuse specifications are 3.3watts so that is right where it should blow - in my opinion. It seems to be a good replacement (I havent tried it- just bookwork booklearning as of now)

I looked up the specifications on TVS diodes of various brands and I havent seen any that give specifications regarding the resistance value - after it blows. My blown TVS unknown brand "FT051 BE" gives a resiatance of 390 ohms and got charred and burned the board around it -probably due to leaving it plugged in after it blew - for who knows how long?

Note I was glad to received the above measurements from the kind person. I am also amazed that the power adapter he used for each one was a switchable universal power adapter - with a selector switch to select between various voltages. It is not normal or typical to have such a tight well-controlled voltage output. Normally a run-of-the-mill average common power supply that is a wall type ac adapter (wall wart type) will vary greatly - for example a 6v DC adapter may actually output upwards of 12V ... 9V ... 7.5V  they are all over the place having no internal regulation (Im not saying the voltage fluctuates). It is VERY risky for the safety of the ABI tester - to plug in a non-abi power adapter.

Update 10/29/16
Linear IC Tester BK 570 also has a TVS diode located inside. The PCB is marked SUP1 and have included a photo of this part with arrows point to it. In case a non-original power adapter is connected to it - this TVS diode will blow - instantly approx 1 nanosecond will turn itself into a resistor cutting off power and preventing damage to the rest of the circuitry.

I have purchased one of these expensive testers and I have learned from experience from ABI Chipmaster that it is VERY important to feed it correct power. Never even slightly higher.

sup1.jpg sup1.jpg
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BK Precision 570 Linear IC Tester purchased used from a Craigslist seller 9/2016 and included manual and ac power adapter 12V. Can run on 2ea standard 9V rectangle batteries or ac power adapter. It is an "out of circuit" tester meaning that the IC needs to be removed from the board (having a socketed chip is easier than desoldering to test) and plugged into the ZIF socket. Some ICs require a capacitor to be inserted from one pin to another pin - according to the manuals notes. The need to run 2ea 9V batteries is odd and my other brand/model linear tester - runs on 2ea 9V batteries also - so as far as portable linear IC testers are concerned - this is normal. It has a built-in self test function. It has a search function or the IC number can be typed using the membrane style keypad. I see an ON button but still havent figured out how to turn it off. It shuts itself off after 3 minutes of non-use. This is my 14th IC tester and - even so has unique chips that I can only test on it. Mfg date of this model tester is approx 1996 to 2004.

I was searching for a linear IC tester to add to my extensive chiplist. This is my third linear IC tester and glad to have acquired it. It is a very expensive unit and commands a high price new or used. As I repair/restore my Rank Cintel telecine from the 1990s and other machines/equipment etc

see my other webpage

... filled with thousands of socketed ICs both linear and digital and my need to check these vast quantities of ICs drives my search for more linear IC testers. The chiplist on this 570 unit is not extensive. The BK570 chiplist versus the BK575 is vastly shorter in length but one is a digital tester whereas the other is for testing analog/linear chips - so the comparison is like comparing apples and oranges - two different things. Despite its relatively much shorter list of chips that it can test - I value it greatly due to the high quality and uniqueness of the chips it can test. I really needed this unit in my daily repairs - and very glad to own it and use it. There arent that many brands of linear or analog IC testers on the market and my philosophy of "test a chip on as many testers as possible" is quite limited since I only own 3 brands/models of linear testers.

A "twin sister" tester to the BK Precision 570 is the ABI LinearMaster which is a look-a-like and functionally-equivalent (case color difference). Either model/brand is wonderful to own and use.

The Gold standard is the BK Precision and ABI - both linear and digital. Top of the line. I value ALL testers and I still continue to test all ICs in question on multiple machines. Even at the high price - it is worth every penny.

Microcontroller Based IC Tester (Caseless and purchased New Sealed from big-auction-sites)

This is my IC Tester number 12

Microcontroller Based IC Tester which has no name-brand and has no case.
This was purchased 2014 from big-auction site and was difficult to obtain because I waited too long to buy it and at that time only one seller for this item remained. It was actually cancelled by 2 sellers which I tried to purchase from. One seller from another auction website told me the reason he cancelled was that he mailed it and then it came back with reason "Failed Xray Test" which means that security would not allow it to be mailed internationally. But I finally successfully ordered it from anotgher seller (same seller who cancelled originally) and arrived - great its finally here! Very hard to purchase but worth the wait.

There were no instructions that came with this tester. The original Ad that I purchased from showed the chiplist and I have included all the information inside this Zip File which I created.

ONE very important thing which was not on the website - not printed on the circuit board - not anywhere.

The polarity of the power connector is center pin is positive +
The voltage required is 7-12volts DC.
(I use a 9v standard rectangle battery)

I made myself a power cord with a 9v battery clip and then connected it by soldering and heatshrink tubing to a DC power plug which I had in my inventory. I traced the electrolytic capcitors negative - side with a continuity tester (Fluke 73 multimeter set to continuity) and I knew that whichever part of the power jack had continuity with negative-side of the electrolytic capacitors was also minus on the DC power jack.

That polarity description is nowhere to be found anywhere online - I wonder how many people blew out their IC tester by hooking up the polarity wrong? I hope not. There is no voltage regulator on the circuit board. I recommend only running it on 9v battery power.

I tests well and has a very short chiplist - I'm glad to have it.

I purchased several cases and a keyboard and 9v battery compartments etc and I will decide/modify a case to work - will update this post as I figure out/modify a case for it.

I have added the chiplist on the bottom of page lefthand side "MBICT" and is only for a short list of 7400 chip testing.
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Caseless IC Tester model TES200

Purchased this from Hong Kong and is brand new. I jumped on purchasing this new item as it has a long chiplist and price is low. I didnt want to miss an opportunity to buy it - by waiting too long. (I am having trouble acquiring another caseless tester