[urq] CGT Digital Cluster

[Steve Eiche]

Eric,
The digital dashes are tricky.  The LCD panels can be fixed with the 
rear window defogger repair conductive paint, but it is kind of a one 
shot deal.  Only do it once the dash is working and you don't plan on 
taking it apart again.  Also, make sure that you do not touch the face 
of the LCD panels as it is almost impossible to clean them without 
scratching the coating.  They are extremely fragile.

As for the bulbs, they run off of modulated AC current to control 
brightness, not DC.  Those bulbs WILL blow if you connect them to 12VDC 
(assuming that the correct bulbs are in it).  The processor and other 
circuitry must be up and running for the bulbs to light.  The idiot 
lights are independent, so it doesn't mean much if they work.

The circuitry is not terribly robust and there are a few failure points. 
  You pretty much need an oscilloscope to trouble shoot it.  I have 
repaired a few over the years, so I am fairly familiar with them.  If 
your LCD panels are good, you might consider repairing it.  If they are 
scratched and the traces on the glass are damaged, I would consider it junk.

Just my .02

Steve

Speaking of instrument clusters...  I picked up an '86 CGT just for the
straight driver's door (don't ask).  Anyway, it's got the digital
cluster, but it's dead.  I took it apart to try to diagnose.  The most
obvious problem is where the ribbon cables connect to the LCD glass.  It
appears that the contact points have worn off the glass.  Anyone know of
a satisfactory way to restore these?  I'm thinking maybe a thin coat of
electrically conductive nail polish...

Of course, there may be other issues with this thing.  The idiot lights
work, but the contacts for the big 4.5W halogen bulbs for the LCDs don't
show any voltage.  I have dreams of putting this thing in the urq.  I
know, it looks cheesy, but somehow it just fits with the vintage.  Oh,
another cool thing the CGT has is an original Blaupunkt (Portland?)
aftermarket head unit.  It's virtually identical to the original Audi
unit.

Eric R.
'86 urq
'93 urS