Trans Computer- Update

[Greg Linstad <greglinstad@xxxx>]

Thanks to Adam, David, Elvis, John, Martin, Nick, and Rick who responded
last month to my post about replacing the infamous blown caps.

I'm pleased to report that with help from those listed above and the
excellent write-up with pictures in the archives by Mark Hershey (thank
you Mark wherever you are!) the tranny in VIN# 6214 now shifts
perfectly.
After removal of the computer assembly and inspection of the 2 circuit
boards inside (each about 2 by 2.5 inches), I discovered that one of the
caps was in fact blown out like Mark's picture showed and the other was
starting to bulge out. Remember this car sat for years and has less than
10,000 miles. I located the replacement parts (most from an on-line
source like Digikey or Newark) and prepared to remove parts. I did not
totally unsolder the boards from the cable they are attached to, just
carefully spread them apart to be able to work on both sides. Removal of
the conformal coating to get a clean surface for soldering proved more
difficult than I expected. After trying every solvent I had, I obtained
the best results using a furniture stripper gel that dissolved the
coating very well. I used a copper mesh strip called Solder-Wick to
remove the solder from the areas of rework, which 'soaked up' the
existing solder when hot enough so the parts just fell out. I decided to
use the highest value cap suggested (50 volt tantalum) which was larger
than the old ones and would not allow the board to slide back into the
slot in the housing. These slots orient the boards parallel to the sides
of the housing, but due to the larger size of the 2 caps I put the first
board into the second one's slot with the other board not in a slot but
resting against the inner corner. This made the boards sit at an angle
but still held in place within the housing (anyone who has seen these
boards will understand what I mean). Sprayed new conformal coating on
the repairs, put that white conductive grease on the 2 replaced
transistors, put everything back together, drove the car to work this
morning and it shifted like a new car.
If anyone else is thinking of doing this, you should try. It is not at
all that difficult.

Greg Linstad
pndc.org
VIN # 3507 121,000+ miles 5 speed
VIN# 6214 9,600 miles Automatic (now shifting perfectly)