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.

 

Hello, thank you for your reply. I tried it, lamp is working but the main voltage on the IGBT's drain is very low. I also tried to drive the disconnected motor, with an external power supply in order to check the motor's windings and carbon brushes. Unfortunately I have only a 40Vds 5A power supply but in any case, motor is running. So I checked the opto isolator statically on the diode side and seems ok. SCR has been replaced. I can not check the micro's PWM pin 12 and the NPN 2N4401 transistor. As far I understood the micro is modulating with optocoupler and SCR the main voltage provided to the IGBT = speed control, while pin6 = micro out and pin4 = micro input are regulating PWM for current control. Correct? So i will recheck the input rectifying bridge. By the way do you have the right schema? I think I have a wrong one, main capacitor is 1500uF@ 200V <=> wrong since I use 240Vac input -> 338Vdc. Thank you. Have a nice day