My treadmill MC 60 control board does not run the motor.When I try to start the treadmill only the speed control diode lights up.The diode that shows that power is on the board does not light.There is 120VAC going to the board.I have checked all resistors,and diodes and they're ok.I have also replaced the two Lm324 ic. Any help would be appreciated.

 

Did you check the leds and SCRs? I've seen faulty leds on these boards that prevents the machine from running.

 

If the power LED does not light then it indicates you do not have the 12VDC supply maybe.
Do you have the schematic?
Measure across zener D10 for 12v.
Max.

 

If the power LED does not light then it indicates you do not have the 12VDC supply maybe.
Do you have the schematic?
Measure across zener D10 for 12v.
Max.

Yes it’s reading 11.5 volts

 

Did you check the leds and SCRs? I've seen faulty leds on these boards that prevents the machine from running.

They are good

 

Another common problem is the MOC3052 opto, there is a LED right next to it, does it light?
Max.

 

Another common problem is the MOC3052 opto, there is a LED right next to it, does it light?
Max.

No it does not.When I slide the speed control knob up the speed control led lights up and fades out when I slide down .

 

Which LED is this? D7?
Max.

 

Which LED is this? D7?
Max.

Yes D7

 

Then it is acting normal and (attempting to) control the Opto, it could then indicate the common problem I mentioned in #6 and the opto itself is shot.
Max.

 

Then it is acting normal and (attempting to) control the Opto, it could then indicate the common problem I mentioned in #6 and the opto itself is shot.
Max.

Ok thanks will see if I can get it and will inform you on progress.

 

Once I repaired three of these boards, two of them had a led on open circuit, and the other had a bad LM324.

 

A faulty ON LED in itself should not cause a problem as it is just an indicator.
Max.

 

A faulty ON LED in itself should not cause a problem as it is just an indicator.
Max.

I don't remember now which led was faulty, but for sure, it wasn't one just for indicator. I think it was the SCR trigger led.

 

If the LED connected to the pin 2 of the MOC3052 is varying it normally shows that the input to the opto is active, if so it could be the opto output.
Others have found this opto an issue so it would not cost that much to replace it.
Max.

 

Once I repaired three of these boards, two of them had a led on open circuit, and the other had a bad LM324.

I replaced both Lm 324 and the leds are ok as are the resistors and diodes.Im looking at the moc 3052.

 

If the LED connected to the pin 2 of the MOC3052 is varying it normally shows that the input to the opto is active, if so it could be the opto output.
Others have found this opto an issue so it would not cost that much to replace it.
Max.

If I remove the moc 3052 from a working board and put in this one I’m having problems with is there a chance it might get hit.I can’t afford to damage it cause it is hard to get and I would have to import it.

 

You would need to use some recognized de-soldering method, the pump or solder sucker is usually best, or copper braid in a pinch.
Or measure or scope the output and see if you get a changing signal.
Max.

 

You would need to use some recognized de-soldering method, the pump or solder sucker is usually best, or copper braid in a pinch.
Or measure or scope the output and see if you get a changing signal.
Max.

I change the moc 3052 and the same problem it’s only the capacitors left for me to change.I think l have an open circuit some place on the board

 

I change the moc 3052 and the same problem it’s only the capacitors left for me to change.I think l have an open circuit some place on the board

I tried another moc 3052 and it woks now.Thank you and all others who had an input.Thanks again.