MC2100 Motor Controller treadmill

Thread Starter

martinamw

Joined Dec 14, 2023
7
Hi All

Really hoping I can back into my electronic repair hobby with some help. I had a treadmill “run-away” speed went full and a MOSFET blew. I replaced IRFP250N properly with the insulating/thermal pad. Now the motor works but it has no strength, no torque - as if it’s not getting enough current.

This seems to be common issue from browsing the threads - any help appreciated.

Martin
 

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Thread Starter

martinamw

Joined Dec 14, 2023
7
The actual board though is the same as one i’ve seen around these threads. With the reverse engineered schematic - I confirmed the PWM signal and speed sensor. I have a burn mark on heat sink next to the high power white resistor - although it is reading correct value (3.3k I believe).

I’ve seen a lot of threads with the same issue. After replacing the FET - the motor works, but has no “strength” to it. I could stop it with my hand on the belt. The DC power is ramping up - although on the oscilloscope - the power looks dirty, not a clean power signal - if i look at 10us timing.
 

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MaxHeadRoom

Joined Jul 18, 2013
28,829
Have you tried the motor on a separate supply?
It should have quite a bit of torque, even on a 12v automotive battery. Check current at the same time with the test and some load applied.
 

Thread Starter

martinamw

Joined Dec 14, 2023
7
Higher the V the better .
Hi - so I attached an old xbox PSU (12v - 16amp)
Motors spins at constant speed, but has same low torque issue. I could stop motor with my hand - I suppose at this point it seems the motor is bad ?

Up to this point I’ve replaced all the components on the heatsink. Motor is measuring ~ 1ohm across it.

Thanks
 
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