85V on 200V Primary?

[mockingbird]

I have a PSU I recapped, but when I turn it on, nothing happens. I checked one of the primaries and it is only showing 85V.

Can someone point me in the right direction? Maye one of the MOSFETs are blown?

[momaka]

Re: 85V on 200V Primary?

Does the PSU have 2x 200v primary caps? APFC?

The only two possible explanations I have for this is if you live in a country where the line voltage is 115 VAC and
- the voltage-selecting switch on the PSU is in the 230V position (assuming the PSU is PPFC or no PFC)
*OR*
- the PSU is APFC but the APFC circuit is not working.

Pictures would be helpful if you have some.s

[mockingbird]

Re: 85V on 200V Primary?

Yes, it has 2 200V big caps.

So if it is active PFC, there would be no switch, right?

It's made by this company:
http://www.ace-power.com.tw/

I will try to take some pics. Thanks.

[momaka]

Re: 85V on 200V Primary?

Yes, it has 2 200V big caps.
So if it is active PFC, there would be no switch, right?

Correct.

The 85v you're getting across each cap is normal if the APFC isn't working or turning on. Reason why is because line voltage is 110-120 VAC (RMS). The rectified (peak) voltage is sqrt(2) times that, or about 160-170V. Since the caps are in series across that voltage, each one gets half of that voltage, which is roughly what you got.