Control Board is a 08 0052. Powers up but no belt movement. Gives error code for no belt movement. Belt and motor are free. Led flashes when moving motor by hand. Motor runs from a car battery. Fuses check good.
I can measure 84 vdc at the motor's black lead to chassis ground. That point also shows 72 vac ac (with blocking capacitor to meter).

Had no scope so I could not tell if the dc voltage was pulse-width modulated or ac ripple. Any thoughts on these measurements?
Schematic would help.
Thanks

 

Measurement to ground is meaningless, the voltage across the motor would be the one to take.
Check any fuse and if good, then the power semi's are the first suspect.
Post pic of the board.
Max.

 

Measurement to ground is meaningless, the voltage across the motor would be the one to take.
Check any fuse and if good, then the power semi's are the first suspect.
Post pic of the board.
Max.

Thanks Max
Fuses were checked and good. No voltage across motor, not even a blip when "start" was pushed. Motor does run when connected to car battery.
Just checking to see what is normal and no doubt ground measurements are useless. I do not currently have access to machine so no picture is available at this time.

 

So at this time it is pure guess work!
Max.

 

So at this time it is pure guess work!
Max.

Max is right. There is no use to measure voltage readings referencing Frame Ground, all drive circuits are isolated from that chassis.
As Max said, check the switching Fet(s) and kickback diode for faults. The flashing LED you see when you move the belt is the feedback circuit for a front roller or motor encoder, which watched speeds. This says there is valid bias power from the MCB or lower board. There should be an LED Marked PWM on the lower board? If so, let's watch this LED when you press start, in which it should begin to glow or flash to show there is a drive speed command signal getting to the MCB. If there is no LED like this, then servicers will need to use a scope to check for incoming PWM.
If there is an LED but it doesn't light when pressing start, I might double check console cables and console connections. Pics would help.
Good Luck!