I am not sure if this is the right place to post, but I see a lot of other discussions on known issues with MC-60.

I have an older (old) treadmill (Spacesave 580i) where the speed pot has simply stopped operating correctly. When I adjust the speed up just a little, the treadmill starts running at full speed with no intermediate setting whatsoever. The speed is set by a slider pot that appears to have a 16k range, up on the user panel. When I take this out and test it with the multimeter, it appears to be working correctly - I have ~2 ohms at low end and 16k at the high (from GND). However, when I go through the calibration sequence with the treadmill powered, the value indicated for that pot counts from 0 up to 255 and resets to 0 about 80% of the way up, then continues to count to ~30.

The panel board seems pretty simple - the brain is a PIC16 uController. I was thinking that many of the resistors on the panel board set dividers that set the voltage input but I don't know if the uController gets involved, or where the PWM is calculated that sets the actual speed (is this way down on the MC-60?).

So, the big question is - is this a problem with the panel board up top or the MC-60 in the base of the unit? The only thing throwing off my suspicion of the MC-60 is that the pot seems to be fine with the multimeter but the displayed value has that weird overflow.

Thanks for any help you can provide.

 

I'm looking at this more and had a few additional questions. It looks like there are three inputs (presumably from a pot) on the MC-60 and plenty of videos on the web showing how to hook these up directly. On my treadmill there is a power supply board (pb-12l) next to the MC-60 that connects to these three signals (H,L, and W) on the MC-60. I can only guess then that the control panel up top encodes my speed setting from the slider and sends that through the single PWM wire down to the the pb-12l.

If that is the case then I can start narrowing this down. I've already eliminated the slider at the top. That leaves either the encoding of that slider value (iffy) or the decoding of the PWM signal at the power supply or the motor control board.

Thanks for any additional support or confirmation!