Low Standby voltage on Dell PSU

[Gatolina]

Hello! I'm trying to fix this Dell ATX PSU H235PD-01 which had a burned tny279 for the 5V Standby.

I've changed it, checked the capacitors and diodes. Now I have 5.8V in pin 2 (bypass), 358V in Drain (pin 4), reaching the primary of the transformer but only 0.7v outputting to Standby purple wire.

What could be the problem? Thank you

[R_J]

Re: Low Standby voltage on Dell PSU

You are missing the feedback voltage from the transformer Check the feedback diode,resistor and replace the electrolytic on that line.

[Gatolina]

Re: Low Standby voltage on Dell PSU

Thanks for the reply. I'll check that. Best regards

[Gatolina]

Re: Low Standby voltage on Dell PSU

If someone else is having the same problem, it was a zener diode connected to the En pin (pin 1) that was faulty.