3 Fried Side Cars

[acastagna]

My Electrical/Programming team had been making good progress until today when we fried 3 digital side cars. We had a functioning drive system on our test frame and successfully tested relays that would be used for our pneumatics and vacuum pick-up system.

After assembling the pneumatics hardware - compressor/relay/pressure switch and solenoid and setting up our Java code, we turned on power while but got only a brief burp out of the compressor and then smelled smoke from the side car.

We quickly killing power and carefully checked the code, wiring and hardware - everything checked out OK. We removed everything that had been added since our last successful operation (pneumatics and vacuum pump), replaced the side car, and turned power back on - only to get another smoking side car.

This time we removed everything on the side car except the power supply and the ribbon cable, double checked everything again including voltage going to the side car, and proceeded to fry a third side car. A post mortem revealed one obviously roasted IC chip inside.

We were utterly perplexed, until one student noticed that the ribbon cable going from the CRIO to side car was not neatly trimmed and the excess at the end was butted up again the solenoid breakout board on the next CRIO slot - right against a row of protruding and quite pointy solder beads!

We fixed our ribbon cable, but haven't yet risked a fourth side car. Does anyone have any insight as to whether its is feasible for an unprotected end of a ribbon cable to short against a breakout board and cause a smoking side car? Also, is it possible we could have damaged the breakout board or modules?