what kind of damage?

Hi all,
Any electronics experts that can help me with my '95 Audi S6?
A few months ago, the tach started doing strange things and the analog clock didn't work. I pulled thee instrument cluster and found a damaged circuit board. I found a used cluster and installed it. All was well but a couple of illumination bulbs were burned out. I waited a few weeks for warmer weather, pulled the cluster and replaced the bulbs. Reinstalled and the lights worked, but no tach, speedo, engine check display or clock. Pulled the cluster again, removed the rear cover and found this circuit board damaged in the same place as the original. The cover rubs on the board and damages it. I repaired the circuit board and now the clock works but no tach, speedo or display. Replaced the display with the old one. Still nothing. Any ideas? A reboot?
Don't suggest that I buy another car. I did. (2007 Audi A3 Avant 3.2 S line with DSG gearbox and real paddle shifters)

Oh, and we got three inches of snow today.


Ed

is a circuit on the board getting broken? photo would be great if possible.

--
MY 2000 S, Ocean Blue, Metropol Blue, Savanah Beige.
Bought June 2000 - Sold May 2010

The printed circuits on the board are abraded by the cover and break. In some cases short out on other circuits. I'll try to get a pic, but it won't be easy. They are tiny.

Ed B

OK, I would do the following:
1) clean sensor and connector ends
2) clean grounds at firewall and fuse box
3) check harness for mouse damage, IE chewing through protective shielding

I love Audi's, but, there attention to detail when it comes to electronics leaves something to be desired. My guess is, there is a bad ground , and/or higher then normal resistance(IE dirt/debris, pinch, mouse damage through harness, etc). You might ohm out the sensor, as it might be failing to ground, or shorting, but that is unusual. Nice car, always loved those engines.
regards

I've checked the items you suggest. I tried the old instrument cluster and its old (different) problems are still there. I changed the display unit with no improvement. The tach and speedo run off different sensors although they may use the same chip.

Ed

So, i have no idea what exactly broke. But:

1. on older VWs and Audis the voltage regulator ( a 3 -terminal black plastic device) was known to die. Could be.
2. But you also say the printed circuits are breaking. How? Rubbed off? Cracked? If so, and you can get it out, bridge it -- either with solder or with a small wire that you solder on. If its multi-layer, you're , uh, have a problem.

I dont hear this often. I wonder if something else is causing the issue.

Do you know about "Audifans" - the global mailing list exploder that's been running for about 25 years, originally as the "qlist" out of the University of ??????

Its full of people, including Satch Carlsson last i knew, coaxing old cars to behave.

Grant

Grant,
Thanks for the interest. The cover rubs and breaks the printed circuit in one area and sometimes shorts out other circuits. Both boards failed in the same area, one worse than the other. The tach failures were different and the speedo didn't fail on the first one. I repaired the second board and now the clock works, but still no tach or speedo. All other instruments work. Might be the voltage stabilizer.
I Recently heard about "Audifans" and am working on getting another instrument cluster.

Ed B