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Old 05-16-2022, 04:33 AM   #8
Join Date: Jan 2022
City & State: Cluj-Napoca
My Country: Romania
Line Voltage: 234.6V 50.0Hz right now
I'm a: Knowledge Seeker
Posts: 24
Default Re: ESR 0.6Ω capacitance -15% absolute must change?

Originally Posted by PeteS in CA View Post
So the PFC appears to be working. That plus the 5VSB means your auxiliary regulator is working.

Do you have that 383V at the inverter MOSFET Drain? If not, you may have an open fuse between the PFC and the inverter. If you do have an open fuse, you may have one or more shorted inverter MOSFETs.

Does the controller for the Inverter have Vcc? Do you have the IC part number? Is it on the primary or secondary side?

Does the PWS have 12V and 3.3V Standby outputs? Or simply a 5VSB output with 12V, 5V, and 3.3V main outputs? I suspect it's the latter.
Useful questions, thank you. I will dig more for the answers.

Looking for the IC that does PWM I found several op Amps and a PIC.

Is it possible that this PIC is actually performing the PWM: PIC16F819?

Everything is pretty dense with a secondary vertical board with PIC and OP AMPS. I'll have to take down again 3 heat syncs with MOSFETs and double diodes to track pins and see if I missed another IC. Almost all components are covered by the 3 T-section shaped heat syncs.

I'm bringing in today another working PSU (same model) to see if it actually has 12VSB and 3.3VSB (the bad one does not). I also now have a 12V 21W light bulb and test the PSU under load, since it may not output voltages because of zero load.

I assumed this is EOL and I can probably find an alternative replacement. I'm just using this repair project as learning experience.
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