Home 15A circuit breaker trips when I press the Up speed button to start moving the tread.
Display panel is OK
Elevation up/down OK
LED is on continuously.
Disconnecting the drive belt from the motor to the roller does not change the trip.
The motor works when connected to a 20V battery and drives the tread OK.
If I disconnect the leads to the motor, the there is no trip. A DC multimeter shows voltage that rises and falls with operating the speed up/down buttons.

I haven't seen reports of this behavior in the forums. Anyone encounter this before?

 

What happens with 100w lamp in place of the motor?

 

What happens with 100w lamp in place of the motor?

Well. When there speed is raised by pressing the Up Botton once, the bulb flashes for a fraction of a second, then is dark. A second or third press of Up does not change the light. Returning to zero and pressing Up once again flashes for a fraction of a second.
With no light connected, pressing Up once shows about 120V DC, which then falls by about 2-3V/second. Another press Up and another 120V that also decays.

 

Can you post a photo of the board?

 

 

New information.
The same first step Up from zero speed will light a 7.5W bulb for almost one second. A 90W bulb turns off much quicker.
In calibration mode, fifth page, the status is zero before raising speed from zero. The status changes to one, 1-2 seconds after the first Up step. The documentation from the thread sticky page says a status of one indicates that the controller is in the Reset state.

When a high impedance DVM is the only load, a step Up from zero speed also changes to Reset. The voltage at the unloaded motor terminals goes to 120V DC at the moment of step Up. The voltage falls to 80V in 10 seconds. When the step Down back to zero speed is pressed, the status changes from one back to zero after 1-2 seconds.

Perhaps this Reset would occur for a large current foldback (but not expected for these small loads). Maybe a component failure is dropping a bad signal on the current sense circuit? I don't know enough to know what other conditions can bring on the reset status. When the motor is connected as the load, the outlet 15A breaker trips.

Also, there has never been a surge suppressor used in the AC line connection (and always connected to the same AC outlet - there is no difference if other outlets are tried). It ran OK for 15 years. The new circuit breaker tripping has just recently appeared.

 

Has theSCR ramp up circuit been checked?also the mosfet driver IC.

 

I don't know the approach to checking those parts. Can it be done with a multimeter?

 

Usually in circuit voltage checks, or removal to check, replace if suspect.

 

It looks like the MOSFET has all terminals shorted together. That. looks consistent with the symptoms.

Thanks for the lightbulb tip.

 

Yes, I think must be some component or more is shorted in the board
Any gate drivers in the circuit?, if so, you should check also