Bricking a PCM while on the road?

[Tom H]

if there is no communication to the computer the only way to bring it back to life is by pulling the T side chip and bench flash it with the programmer.

After checking and possibly reseating the PLCC32, I'll try to socket the E side and clean flash it, even though I am pretty certain it has nothing to do with the communication link.
Hopefully I can make this one come back to life.

I detailed a way to reload the PCM without removal of the chip. Look for bootstrap...

The conformal coating is there for a couple of reasons. The coating prevents condensation from forming on the board. This condensation can result in oxidation of the tracks, breakage--> brick. Also, depending on the drive of each of the parts, the leakage can result in errors on the bus --> brick. All the other failure modes relating to sockets --> brick. If you are going to uses a socket, try to find one with a thicker gold plate. Vibration will cause fretting corrosion between IC lead and socket. Just a ton of failure modes. Above it was indicated that the ribbon can fail, I had this also due to handling. This was easy to fix for bench work, but very hard to fix to put it back in service.

Suggest working with an untouched PCM, working through the header and reloading that way. Once the conformal coating is broken, all bets are off. The coating is a PIA for the manufacturer, results in higher scrap, cost of chems, no rework or bed of nails test once complete. They put it there because it was necessary.

Hope this helps -Tom

[winchy2]

Thank you Tom. I agree with you on the conformal coating. Maybe, after I do some checking under a magnifying glass, I can brush in some Urethane or something like that.

Also, looking for the bootstrap info, I got to your other thread on the hardware research you are doing. Pretty amazing stuff! As an EE myself, I love this type of work. Keep it up!