[V8] FROM THE SOUTH OF THE CONTINENT AGAIN

[Mike Arman]

When I had all kinds of weirdness in the instrument cluster, I did the 
reflow soldering trick and that solved everything.


What happened is this - PC boards are soldered with a device called a 
wave solderer. The temperature of the solder has to be hot enough to 
make good connections, but not hot enough so the board or parts get burned.

Problem is that if the temperature is set so the components and the 
board are not damaged, the larger parts (the interconnect pins) don't 
get soldered properly - they are not hot enough. If the temperature is 
hot enough so the interconnect pins are soldered properly, the rest of 
the board may be damaged. This is not limited to Audi PC boards, I have 
seen this in computer power supplies, TVs, etc.

Anyway, here's the fix - remove the dash pad (there is a screw at the 
front center which is hard to get to). Put a shop rag on the dash, and 
remove the instrument cluster. You have to release several wire harness 
plugs, they do NOT just pull apart, yanking on them will damage them, 
and if you think you have problems now . . .

Lay the instrument cluster face down on a soft towel on your workbench, 
and take out the hex head screws that hold the PC boards to the back of 
the assembly - there are a bunch of them, some are hard to find, and DO 
NOT FORCE ANYTHING!!!!.

The boards will lift out, and you will see the interconnect pins which 
transfer signals and power between the boards. Use a magnifying glass 
and take a good hard look under a bright light at where the pins are 
soldered to the boards - you are guaranteed to have some loose pins 
where the solder wasn't hot enough back in 1990 or 1991. Wiggling the 
pins (gently!) will also show this. If it moves, it needs to be resoldered.

Using a soldering pencil of about 25 or 30 watts and some good 
electrical solder (rosin core!), carefully resolder all the pins. You 
might as well do them all, it is a PITA to have to go back later to fix 
one you might have missed.

Use some contact cleaner (Radio Shack or other contact enhancer, the 
stuff is expensive but worth it), and put everything back together, Now 
is also the time to replace any burned out instrument light bulbs, it 
will never be easier.

Reattach wiring harness plugs, install instrument cluster, and check out 
the operation of all functions. Leave the dash pad off until you know 
everything is working correctly. When you reinstall the dash pad, try 
not to drop the center screw down the defroster vent ;-)

Best Regards,

Mike Arman
90V8Q, still a lawn ornament, but I'll get to it soon.