MC-70 treadmill motor board powers up for a few seconds then shuts off

Thread Starter


Joined Jun 1, 2023
Hello! I salvaged an MC-70 motor driver board along with the accompanying T.M. motor from a working unit for use with a DIY pottery wheel. I hooked up a 5K potentiometer to the L/W/H pins, but when I turn on the power and start turning the pot, the relay clicks on for a couple seconds before flipping back off. I'm using an incandecant lightbulb for testing, but the same thing happens when connected to the T.M. motor. It doesn't seem to matter how much I turn the pot, it always flips off after the same amount of time.

I tested all the diodes and the MOSFET isn't shorted, so I'm not sure where to go from here. Any ideas on which components I can test or if I'm missing something obvious?

I've attached a photo of the board and here's a video of the issue. Thanks!