Possible Cortex Motor Controller Burn-Out?

Hi everyone,

Recently, port 1 (2-wire) has been acting up on our cortex. Two days ago, these problems started after we noticed the faint but unmistakable smell of fried electronics. We originally attributed this to the VEXnet key as we had been having issues with it, and upon inspection, it felt very warm. A firmware update has solved these issues.

Later we tried to use the motor in port 1 again and realized that it refused to turn backwards. We looked for anything obstructing it and could not find anything. Then we plugged the motor in to a variable benchtop power supply and it worked fine. We took a multimeter to the brand new 2-wire extension cable we had been using and noticed that the port was outputting 6.2V while the mirror of this port (both on the robot and in code, port 10) was outputting 0V. Forwards, the suspect port outputs 2.3V while the mirror outputs 7.3V, and backwards the suspect outputs -7.3V while the mirror also outputs -7.3V. With this information, we believe that somehow we fried the motor controller in port 1. What would you guys recommend we do about this? Or is there a really obvious problem that we are missing that could be solved to fix this issue?


Team 610X,

Its possible for a motor port to draw too much current, overheat and become damaged.
Also it can be damaged if the motor has a short, please examine the motor and make sure the insulation around the wires is in good shape.
What kind of motor were you using?

Once a motor port is damaged, sometimes we can replace the damaged component and restore the port; however, sometimes the heat damages other components inside the Cortex and the damage is permanent.

I can analyse the damage in your Cortex and let you know if we can repair it, if interested send an email to support@VEXrobotics.com

For now, please use a 3-Wire Y cable to make-up for the lost motor port.



Thanks for the quick response!

We were using a 393 (default internal gearing) at 1:1. The insulation around the wires looks to be good but the rubber grommet is in pretty rough shape.

We are going to make absolutely sure that it is something internal that is broken and then we will get on that e-mail.