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Unread 12-10-2013, 00:16
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Re: Interesting Vexpro Victor 888 failure.

Quote:
Originally Posted by Ether View Post
Did you try pulling the PWM from the "good" Victor on that side to see if the "bad" one ran normally?

http://www.chiefdelphi.com/forums/sh...01&postcount=5

http://www.chiefdelphi.com/forums/sh...1&postcount=19


No, honestly I can say we did not try that.

Quote:
Originally Posted by Jon Stratis View Post
Could the clicking sound you heard come from the breaker powering the victor? Based on "clicking+LED blinking in sync", it could very easily indicate some type of short circuit that's tripping the breaker when you put the victor in reverse. Have you tried running the victor (both forwards and reverse) with no output attached?
Yes.
After seeing the behavior, we put a meter on the output to verify what was being sent to the motors. One had normal 0v to ~12v output based on the joystick's position and the other jumped from 0v to 10v then progressed to ~12v with the joystick.
These same results were also seen when the motor was removed and the output of the bad Victor was read open circuit.

Now that I think of it, it would be quite possible that if one of the FETs in the H bridge were shorted, this behavior would be exhibited.
In one direction, the shorted FET would not conduct until it's paired FET turned on. At this point it would cause lots more current to flow than normal, but the paired FET would still regulate. The current wouldn't trip the breaker because the motor would be limiting the current.
In the opposite direction, it would be shorting out half of the opposing FETs and could easily trip the breaker.

Sounds to me like you may have help explain it Jon!!!
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