I have a ProForm 590s treadmill that started going full speed when I started it for about 2 seconds then would stop. The console worked fine but the unit did nothing. After spending some time researching on the web. I confirmed that the speed sensor was still good by using a multi-meter and doing a continuity test on the sensor. When the sensor was aligned with the magnet on the motor, it was closed and completed the circuit.
After that, I scoured some boards and found this post:
“Yep, control board has a shorted HexFET and/or kickback diode. The MC2100 usually comes back to life by replacing the IRFP250 with IRFP260 or better, check current limit resistor in series with the HexFET. A good signal from the console will show a red blinking LED on the MC2100, when the controller see’s too much motor current, as in a runaway, or a feedback mismatch, it kills the drive to the motor section but will leave power to the console intact usually. Fitness Remedy in Sun Prairie Wisc repairs all kinds of fitness electronics for fractions of replacement costs. Good Luck, and remember, there are lethal voltages on many motor control boards, so take care troubleshooting. signed….former treadmill control board engineer ;o) ”
In any case, I swapped out the MOSFET and the treadmill is now working again. I really appreciate everyone who responded to the other boards. $7 fix versus $160 board.
One item to note, when you solder the new MOSFET in place, make sure the hole aligns properly so that the little bolt will line up with the heatsink hole.
Hopefully this will help some others who may be experiencing a similar issue.