Quote:
Originally Posted by GregGarner
The current theory is ESD on assembly.
If you are skeptical of this, then given the evidence, what is your theory?
I am certainly open to other theories, as my main goal is to figure this out and stop the bleeding!
Here is a quick summary:
1) 2 blown talon SRX devices when working on the robot, may or may not have been moving the motor (we just didn't notice exactly when they stopped working). These 2 were on different motors, and did not blow at the same time. When we replaced the talon we did not change any wiring or any motor, and the talons that were replaced are still working fine. The Talon SRX devices have no LED after they are blown, i.e. the CPU and the regulator were fried. These two were looked at by CrossTheRoadsElectronics and found multiple chips were fried (just nonworking and shorted, the tops were not blown off the chips).
2) 1 more blown Talon SRX, this one apparently went out while we were moving the motors manually, and it may have been powered or not powered on by the battery, not sure. Again the sympton is the LED does not come on at all. Changed the Talon, did not change anything else, replacement Talon is still functioning. This one has not yet been returned for post mortem.
3) Final Talon SRX blown when moving a bag motor. I will verify the symptoms (i.e. no LED) this evening, as I haven't seen it in person yet.
This one has not yet been returned for post mortem.
Note that we are using the PD board with circuit breakers, and we are using a standard FRC battery. This robot has been very carefully assembled, we did not connect up the Talon SRX modules backwards or get the battery polarity backwards. All connections were done with solder, covered by heatshrink (although we are switching back to high amperage connectors now because we suspect we may have to change out Talons in between matches if we can't solve this problem)
GregGarner
3612 Gearhogs
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Were the chips that CTRE found to be damaged connected to "the outside world" or were they only connected "internally"? The ESD would have been amazingly powerful to cause damage past the first device it hits. ESD can cause mis-operation of a device when injected into the system while it is running but I doubt that you would be touching those connections while running your robot.
Perhaps CTRE may want to check their supply chain for counterfeit parts. We have had several instances at work where counterfeit parts sort of work but caused failures where there was no "abuse" of the system.