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?
We’ll double check it. It could be the cause of the second and third failure, but I’m sure the Wago was not touched between successful operation and the first failure.
The sidecar has reverse voltage protection, so you should be OK if you “accidentally” hook it up backwards. :rolleyes:
We blew a sidecar once because we had an excess PWM cable hang down and touch the negative post of our PDB, causing a short. Anything is possible, though I don’t see how a short in the ribbon cable would blow something in the sidecar. Everything in the sidecar is “downstream” of the ribbon cable, and shorting the solenoid breakout to one of the 4 grounds in the ribbon cable would be more likely to blow the solenoid breakout than the sidecar.
This happened to us in 2011 at Boilermaker. We went through 3 digital sidecars and only 1 showed real signs of burn. We checked everything and we didn’t notice anything wrong. Our 4th side car that year works and continues to work. Our only possible cause was the possibility of a case short in a bb 775 motor.
If you’re using the solenoid breakout and have 12V wired to it, I’m liking your theory of the excess ribbon cable touching a 12V circuit on the solenoid breakout. There’s plenty of chips on the sidecar that aren’t expecting 12V and aren’t likely to survive it showing up on an unexpected pin. Even moreso if you’re powering the solenoid board with 24V.
The solenoid breakout and module is likely fine, since it’s rated up for the voltage it’s carrying. If I’m reading the spec sheet for the 9403 module correctly, it can withstand ±30V on the inputs with no ill effects, so it’s probably fine as well. Wouldn’t hurt to test all the channels you’ll be using, however.
This is a long shot, but make sure your power system is healthy from the battery wire issue (improper polarity Anderson Power Plug).
Have you drilled or machined near the DSC? The old ones are not conformally coated, and can short out if you get a little spec of metal in there.
When you mentioned “fixing” the cable, were you referring to moving it away from the protruding solder points or taping up damaged areas? If anything, try a new one on your next test. If it works, throw the old one out.
You might want to break out the multimeter and check everything for continuity. Are your fuses all correct? Have you made any wiring mistakes? Double check everything in accordance to the FIRST manual.
Do you have any BaneBot motors? If you had a BaneBot that was case shorted, for instance, you could have many mysterious electrical problems. If you do have a BaneBot, make sure you machine any OTS transmission to allow for air passages (most, if not all BaneBot issues are overheating related).
Following your description of the ribbon cable, I agree with Kevin. It sound like 12 volts or 24 volts if you are wired for 24 volt solenoids backed up the exposed ribbon and took out the side car. Since there are both inputs and outputs on the ribbon cable, there is likely some serious damage to the sidecar. Pictures are worth a thousand words.
Problem sovled. Thank you to everyone who provided input. The issue was definitely ribbon contact with the solenoid board. Opening up the three side cars revlealed the same chip (U2) was burned. We did some testing and found that only a very light pressure was needed to make electrical contact with the cut end of a ribbon cable, which would send 24 volts into the side car. We tried the ribbon flush and taped the end with electrical tape, and everything works fine with a new side car. Luckily nothing else appears damaged.
So, the lesson learned is secure all possible points of electric contact.
A,
If you take a sharp utility knife you can cut the ribbon cable flush with the IDC connector. Once you cut it, you have to check that no adjacent conductors are exposed or touching other wires in the ribbon. A sharp blade will usually give you no problem. After that, no insulation is needed.