89 cavalier electronic dash

[doc777]

I am trying to repair a electronic dash for a friend. He has a 1989 Cav.
He has tried to find a replacement with no luck. To repair it would be over $150. I am an electronic technician, and am a fairly good car repair guy. I was wondering if anyone knows about this problem and what the fix is. It seems that if you have a car with this dash, you will get this problem.
Here's the problem. WIth a fully charged battery installed, while driving the battery voltage display keeps dropping until the alternator should kick in and rechage the battery. This doesn't happen and the battery goes dead. He's had it to another friend that is a mechcanic. He traced it down to the dash as the probem.