Burned Out Motor Controllers

VEX V5 General Discussion Technical Discussion
1

Today, I was testing motors using the debugger in RobotC, and I looked at my robot to see a bright orange glowing motor controller, a large volume of pink smoke, and a putrid smell. I immediately shut off the cortex and removed the now burned motor controller (I attached an image).

I don’t know what caused this malfunction, but this motor controller is a few years old, it may have just degraded. But if it was something I did wrong, I would like to know what happened. Has anyone else had this issue?

P.S. Two years ago, the same thing happened to a motor controller on my robot, but I wasn’t there to see it.

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2

We end up with burned out motor controllers when there is a short in the motor wire. Often right where the wire exits the motor housing.

3

I am going to replace the motor in question, and hope we don’t have another issues. Thank-you.

4

This happened to a classroom team at our school last year but we dismissed it as not a real problem because it has happened to only one of our many many motor controllers that we have

Hope this helps

5

I would just recommend checking all your motor wires where they exit the motor since I shorted out a cortex a little bit ago cause one of my motors plugged into port 1 shorted and caused the internal h-bridge to short and ignite.

6

I think it was a short in the wire from the motor, there were exposed wires. We replaced the motor, and everything works now. No more ignitions.
Luckily, the port on the cortex still works.

7

You just have to be careful with ports 1 and 10 since they have integrated controllers. If the motor shorts it breaks the cortex whereas the speed controllers protect the cortex.

8

Good to know! Thanks everyone for your input.

9

I’ve had that happen before. The part of of the wire that comes out of the motor is very fragile and delicate and is shorts out unless you are very careful.

10

Motor controllers can burn out even with no short too, so you always need to have a couple spares on hand at competition. Yesterday, we had a robot battery start smoking…smoke just started blowing out the hole where the wires come out! It was an older battery, and must have had some internal short.

Better fix your code for the future:D:

int main()
{
std::NoSmoke;
}

11

We’ve had 4 cortexes burn out on one port due to shorts in motor controllers and in motors. Make sure to inspect wires before using them. Also, watch for any funny business like a wire only working in certain positions. We’ve had 3 motors and two motor controllers, and a Cortex have cold solder joints fresh out of the box.

12

4 Cortexes? Ouch!

Does someone in your team just sit there with a knife and periodically short your cables? :smiley:

13

Yeah 4 cortexes wow. Must have put some sort of dent in the budget