I'm attempting to repair an older treadmill that I received as a gift. When trying to start the treadmill, it is able to power up successfully. But when pressing the start button, it starts counting down from 3 to 0, and it seems like it ever so slightly starts to try the motor before erroring out with an E7 error (Input power anomaly). I'm able to also run the calibration where it starts the motor for a brief second before shutting it off again, and reinitializes the LCD display, moves the incline motor back to its base, and then goes back to normal. (Still has the same startup error though).
I've tried testing the various circuits on the board, and from what I can tell, the components appear to be within their normal range. I believe that the yellowish stuff that is near some of the components is board glue, but I'm not 100% certain of that. The stuff itself appears to be solid. I have no idea how long the treadmill has been in this state though, as I just received it recently. I'm fairly handy with electronics, so any other components that could be tested to determine if they are faulty I could probably do. The new controller board is $250, so if its a 10 cent capacitor, I'd like to start with that approach as opposed to replacing everything for a cheap component.
I've checked as many components as I can reasonably get to, specifically starting with the MOSFETs that drive the motor. My assumption was that it was either having trouble switching those own, or else the capacitors are not charging properly to supply enough power when first starting up the treadmill. I've done the following troubleshooting steps:
1. Connected the motor directly to a power supply to run it (it runs)
2. Checked the RPM cable for the motor when it turns to see if it registers periodically (it does)
3. Tested the incline motor (it goes up and down)
4. I purchased another motor controller (though I think its slightly the wrong one) and it gets an E5 error.
5. Visually inspected the circuit board for any burnt parts / connections (didn't see any)
Unfortunately, I don't have any schematic of the system directly, but I do have a few of the service manual docs that have some advanced troubleshooting steps. Those didn't seem to really help in this particular situation.