I have pcb from mower which is protected by black putty, upon removal damage a few componentsBefore that it was not working as should, during ON it will spin motor in low speed for seconds and turn OFF. Its 40V brushed motor, should be 10A rated circuit as power defined 400W. Its pwm speed control board with some other features like temperature control for pcb and battery. For me it seems that maybe FR1004A could be faulty, other components for failure maybe mofsets? There is AP9579GP and MXP84d7AT. Possible that I get same board with same issues, how to check what is broken here?. Heatsink was removed here.

 

I would say that board is 99.999% unrepairable.
If the FR1004A is bad, chances are there are other parts damaged as well, located under that epoxy stuff.
The effort required would be huge, and even then, the outcome uncertain.

 

I would say that board is 99.999% unrepairable.
If the FR1004A is bad, chances are there are other parts damaged as well, located under that epoxy stuff.
The effort required would be huge, and even then, the outcome uncertain.

but strange that it worked, everytime when you press ON motor spins for second ans stops.

 

but strange that it worked,

.... but you said it was not working as it should. There are numerous reasons why the motor could still spin, but for only a short time. For example, the MCU might sense excess current being drawn by the motor itself or by one of the associated MOSFETs , so shuts down. Or the power supply might be going into self-protect mode because of excess moitored current or temperature, Or some timing component may have failed. Or......

 

.... but you said it was not working as it should. There are numerous reasons why the motor could still spin, but for only a short time. For example, the MCU might sense excess current being drawn by the motor itself or by one of the associated MOSFETs , so shuts down. Or the power supply might be going into self-protect mode because of excess moitored current or temperature, Or some timing component may have failed. Or......

with battery all fine, have two so all the same. With other agree...