Hello
I have the following issue. After replacing the IGBT, freewheel diode, and SCR, the main motor is spinning again, but with very low torque. I can stop the main motor just by hand. Motor speed control is ok. Led flashing, auxiliary motor (= incline motor) is working. Disconnecting but in running condition, the main motor voltage the +AT is low (about +9Vdc).
Optocoupler seems to ok at least on the diode side. I can not check the transistor in cascade to the optocoupler diode.
Current sensing resistor, power capacitor, AT fuse, +5V, trimmer seems ok.
I do not have an oscilloscope, so I can not check the PWM signal nor the micro's watchdog signal.
I do not know if the microcontroller's analog input is still ok, but it is unlikely that all other functions are still ok, except the analog current sensing pin.
I did not change the MIC4227, IRF250's driver, but the motor is spinning. Main motor checked using an external power supply @ +30Vdc -> running, but I do not know the torque and speed.
Could somebody help me?
Thank you. Have a nice day.

 

Did you test/check the MIC4227? In some cases this gets gamaged.

 

no, but without an oscilloscope I do not know how to do it? It is a SMD component. Do you have a suggestion? may be I can check the the input and output frequency with the multimeter? better then nothing

 

Check with voltmeter at full voltage, use 100w lamp in place of motor, if neccessary.