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Unread 31-01-2014, 18:23
F Elliott F Elliott is offline
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FTC #8114
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Join Date: Dec 2013
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Re: [FTC]: Tetrix motor controller weirdness with 4 motors

We are trying to get four v2 motors to work in our drive system. We got away with two v1 motors for our Qualifier but we were the slowest robot on the mat.

Four v2 motors on two controllers, one motor per port. Servos either upstream or downstream twitch out of control whenever the motors are running.

Here is a critical new piece of information:

1. The twitching is dependent on power setting to the motors.

So we started isolating the motors ONE AT TIME and as luck would have it the last motor running on his own still caused the twitching. So we isolated it and put back the other motors one at a time and everything is good. We pulled a brand new V2 motor out of the box and hooked him up to the the bad motors DC connector and all is good.

Conclusion:
We had a defective v2 motor which was affecting everything. The more power you command to it the worse it gets. I suspect this motor has some sort of intermittent short or weakness in it or something to cause temporary high current demand that pulls power below that needed for stable power to the servo controllers.

I believe now this was the same motor I tried for our lift motor in December. It was probably shipped as defective. Like an idiot I didn't label them and just put them back in the kit.

To trouble shoot, isolate and swap v2 motors one at a time. You might have one or more defective v2 motors in your robot.
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