Microwave oven shutdown problem

[SABER.MAHDAVIFAR]

Hello. This is a Hardstone brand microwave oven board. It had a power failure problem. The power supply was broken and the power problem was solved by replacing the switching IC. The 12 and 5 voltages are OK. Now the device does not turn on when the power button is pressed. I tested the power pins of the display board ICs, which are the microcontroller and LED driver, and they all have voltage and none are shorted. Why does the device not turn on? How can I test the microcontroller other than by testing the voltage? Thanks.
18:41

 

[MrAl]

Hello. This is a Hardstone brand microwave oven board. It had a power failure problem. The power supply was broken and the power problem was solved by replacing the switching IC. The 12 and 5 voltages are OK. Now the device does not turn on when the power button is pressed. I tested the power pins of the display board ICs, which are the microcontroller and LED driver, and they all have voltage and none are shorted. Why does the device not turn on? How can I test the microcontroller other than by testing the voltage? Thanks.
18:41

Hi,

What caused the failure? That could tell us where to look.

You would probably have to know what each pin of the controller IC was used for, but if you can narrow it down to just the pin that turns the power elements on maybe you could check that.

 

[Doug]

Looks like solder short pins 19 20 of the 4rth picture
Tm15??? Ic

 

[Nigel Goodwin]

Looks like solder short pins 19 20 of the 4rth picture
Tm15??? Ic

The TM1638 is just a display driver, and while I see your concern in picture 4, there's no sign of it in picture 5?.