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Мои познания в ремонте данного вида техники: Занимаюсь ремонтом
Наличие схемы: no
Hi guys, I have a power supply module mounted in a Bang & Olufsen speaker that won't turn on. I found a blown 100nF capacitor and replaced it. Now it still won't turn on, but only because the PWM 3845B isn't receiving power. If I try to power it with 12V and then turn on the 230V lamp, the board works perfectly, supplying the dual 38V and 12V to the secondary.
The problem is therefore in the circuit that creates the first cycle to start the PWM 3845B and the part that needs to self-oscillate.
If, while it's on, I remove the 12V (which I supply externally with my benchtop power supply) between pin 7 and pin 5, the entire power supply shuts down, which means it's not continuing to draw the 12V from the secondary to keep it on.
I'm attaching some photos.
The board is an IcePower board, and there are no schematics.
In one photo, I captured the output of the transformer that's supposed to power the PWM, and when I turn it on, I get about 1.2V at point A, so that's not good.
What do you recommend I check?
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