Bought a used treadmill. When I got it home I found the belt was no longer working. I also found a bunch of mouse poop inside the controller area with some on the board...nice.

I used a brushed and vacuum to get it off as best I could.

The SCR led does not light up, but the speed control one does.

I think I traced the issue to the R21 resistor. I have no continuity across the resistor and with the treadmill set at 6, I get 7V on one side and nothing on the other.

I can try to just replace that resistor, but I worry that it will just pop again.

Any advice on how I can try to check the board out further? Also what should I clean it with?

 

I'd use Isopropyl alcohol and a disposable brush to clean it.

 

My schematic shows R21 to be 80k.
Max.

 

Weird the one I have shows 100k

 

That reverse engineered one also had a note that it should be 100k but a 80k was actually in that particular one.
So go with 100k.
I sold the MC-60, just have the MC2100 right now.
Max.

 

Replacing the 100k resistor did the trick! Thanks for the help. This site is awesome!