Electronics > Repair

Sony J30 PSU repair

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Harry_22:
Next connect DC power supply +12,5V to central pin of FCH30A04 (red circle on PCB). And check the rest voltages (in circles).

john2021:
I tested Q7 and Q8 I think they are OK.

I meant that the higher voltage was on these transistors Q7 and Q8. They are K3233. Now I get 12-14v from their legs to ground.

FCH30A04 had zero voltage between any legs and shorted between any legs and also with the white diode. Where can I test for input voltage for it?

I will look for a replacement for it.

What you circled green oval is exactly where there was a white diode I removed. What type is it?

I connected 12.5v as you suggested and tested all the points they are all OK. THAT IS GREAT BECAUSE SECONDARY IS WORKING.

Thank you again very much

Harry_22:
Good!
Please send me the photo of "white diode".

Please try to check again the controller name seems it is not L6574D. Try to look at it from different angles to the light.

john2021:
The white diode looks like the white diodes on Q7 Q8 (see photo).

The ST L6574D is visible in the photos I took and see also a stock photo.

Harry_22:
White diode is a capacitor. It is required for RC snabber for resonance suppression.
Please check it and if it is not shorted put it back.

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