Cortex Caught on Fire

Today I was testing all of our motors in preparation for the start of the season. I would keep the cortex on as I plugged the motor into the 1st port, ran the motor for about a second, unplugged it and set it off to the side. However, when I plugged in the last motor and tested it I heard a small noise and smelled burning plastic. I looked down and saw a small flame under the plastic. I immediately turned the cortex off and unplugged everything, after a few seconds the flame went out. I want to get some help to find out what went wrong so that this doesn’t happen again.

I took the cortex apart so that you can see where the fire had burned, it was not a very big one but if this had happened during a competition It could have gone unnoticed for a while and grown.

Thank you for your help!
burned cortex 1.JPG
Burned cortex 2.JPG

Check the motor wires where they enter the motor housing. The insulation is probably cracked and it shorted out at that point. Many teams avoid using ports 1 and 10 with their built-in motor controller. On ports 2-9, you’ll burn up a $10 MC29 instead of the Cortex when you have a short.

After the burn out I continued the testing. Different motor, different code, different battery, and instead of using the vex-net keys I used the usb cord. It happened again. It was the first motor I plugged in this time. Both of the motors had no damage to the insulation. I think it may be the controller just because that was the only constant. Is there anything that could have caused something like that to happen with the controller?

Again, a short circuit. Also, using the VEXNet keys versus the USB A-to-A cable should make no difference in this case. And no code should cause your cortex to burn. :slight_smile: Bear in mind that the motor wire insulation can be (and often is!) worn within the casing of the motor. But, probably not on two different motors.

If you absolutely sure of the motor insulation (99% of the time), both inside and outside the case, I’d switch to VEX Tech Support, probably give them a phone call…