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Phase A not working and GVDD_OV/GVDD_UV DRV faults

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Joined: 2019-04-01 15:08
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Phase A not working and GVDD_OV/GVDD_UV DRV faults

I have a VESC6 derivative (ESCape) to which I accidentally applied 5V to the 3.3V rail when using an ST-Link. I then attempted to repair it, and now have a series of issues.

The MCU was immediately toast so I replaced it. I could then connect to the VESC tool, but the motor would not rotate smoothly and stutter when started from stationary. I unplugged each phase in turn, B and C resulted in the motor just buzzing without any movement, and but unplugging A had no effect. Based on this I believed that the A phase was not functioning. I read that this could be caused by a dead AD8418, which from the schematic was on the 3.3V rail (although 5V should still be withing absolute max ratings). I replaced the AD8418, but messed up the orientation, so on plugging in the board it burned and gave off smoke. I immediately unplugged the VESC, then purchased another replacement. I installed the replacement correctly, but the board would not power up. I found the LM3671 DCDC converter was getting hot, so I replaced that and the board was booting again, but phase A was still dead. I power cycled the board a few times, tried different modes, and nothing had any effect, except that the last time I powered on the board, and tried to run the motor using the arrow keys, I got a red blinking light and error "DRV" in VESC tool.

I replaced the DRV8301, and for a few minutes I was back to 2 phases working, before it starting showing the same error. I replaced it again with my third and final (!!!) DRV8301, which immediately gave the error.

I read the fault codes, which report "GVDD_UV" normally, then "FAULT GVDD_OV" when I try to run the motor. I measured AVDD to be 6.6V and GVDD to be a *constant* 11V using a multimeter.

What do I do?

Any advice/help would be greatly appreciated.