Alek,
Had a few work projects to do, so I was away for a few days.
Finally got to see the PCB pix you PDF file posted a ways back, and by looking at the boards design my guess is that it was made 30+ years ago or so. Where did you get the TES-6102 reference from, or is that just a tag name you put on it?
What part of the world are you located in?
Do you remember what you were working on at the time that the PCB in ? was floating around the “school's electronics cabinet” (in what specific area of the school btw). Are we talking about a Science Lab or Physics Lab by chance?
I’m just trying to relate as to what “certain equip” of that time era was floating around the public is why.
From looking at the PCB’s backside it very evident that someone was not very good at solder R&R work, as there are so many cold solder points all over the board that it isn’t funny. After looking closer at that pix and seeing all those cold solder spots on the backside it was quite evident that someone tried to T/S that board prior (unless you had done that resoldering work?), but evidently in the process couldn’t find any bad components. There also appears to possibly be 2 bad resistors on that board as well as one looks to be slightly overheated, and the other one only appears to have one color band on it unless the colors are really faded??
That missing R23 looks to be a 1 or 2 watt resistor - as by the PCB hole gaps, and most likely it was a round type, and not a sandstone ceramic like R22 next to it. I would also guess that it was less then 10 ohms as well. When I see or work on ckts that have a higher wattage R like that of the 5-watt 2K ohm R22, and then another higher wattage R right next door it usually is the case, as R23 is mainly there acting as a surge resistor.
Even if that bad R23 was there (burnt bad or not), and it was replaced with a good R of equal wattage & value I doubt that board would work with all those cold solder joints there.
Your best hope of ever finding another know good PCB similar to that what you are looking for would be to take those pretty clear topside (JPEGS ONLY btw) photos you have there and post them on Craigslist under the category headings COMMUNITY or else WANTED, and make sure you word the post properly so as to help in identifying the PCB.
Depending on what country you are in you might want to target more then one area so as to overlap geographical areas and get more responses back.
You just never know - as I’ve done it before when I was looking for an identical piece of older automotive analyzer equip that I had all but successfully repaired - if not for the fact that a certain R was substituted for a Zener diode no less (I believe it was). The unit actually worked in some strange capacity believe it or not (not accurately though) - until that is - it was switched into the 24-volt test mode, and that’s when 2 certain under-wattaged R’s got super heated, and then one actually burned up being too low in wattage rating. There was also a secondary calibration procedure that was missing from the reference manual, but that part I had figured out anyway so no biggie even though it would have been nice to have.
Why that Zener diode was sub’d for an R value in the first place is beyond me, but seeings it was an older piece of test equip, and was pretty old LED display technology stuff it’s anyone’s guess. Things like that happened with those older Mfr companies - as QA wasn’t always cutting edge back then.
Beings that Zener diode was there being used as a voltage reference source, esp in the 24-volt test mode, and then seeings that it was missing from the PCB at time of mfr for some strange reason - well - it’s easy to see what caused the unit to fail.
I just missed someone on Ebay selling an identical test unit by maybe 1 or 2 days. Didn’t really care if theirs worked or not, as all I wanted to know is what PCB component was missing and what it was. I also would have paid a finder’s fee for getting a secondary copy of that CAL procedure as well. Oh well….
If you get no hits from the C/L search then next stop is the trash can, as other then that 2K ohm power resistor and that heat sink on the board there isn’t much else worth gutting.
Hope someone answers your C/L post…
Good luck Alek!
Frank