Dell/LITEON 53WG5 PS-3231-9DA PFC TOP PSU works for a few seconds and turns off

[karapuzo]

Hello,

I would appreciate if someone could point me in the right direction diagnosing a fault with a PFC PSU and potential things to check. 

Dell/LITEON 53WG5 PS-3231-9DA PFC PSU , works for a few seconds and turns off using the relay. (under load or without load, same behavior).
After that it will not turn on for about 30 seconds and the  same behavior persists.

The TOPSwitch TOP266VG chip is very hot, even without load. I suspect it goes into thermal protection mode or some other protection mode (unclear why).
The capacitors are visually ok. Tested most of the capacitors out of circuit, all fine. Transistors are not shorted, rectifier ok, discrete diodes ok, the capacitor shows 380 volts dc (meaning boost and rectifier work).
Didn't find dry solder joints, output voltage while the PSU is on is normal, 12v, 5v.

Tried looking for the schematic but couldn't find it.
Pictures attached, much appreciated.

[karapuzo]

Couldn't diagnose it, will be looking for a small factor psu to replace it.
Meanwhile I butchered an old ATX PSU I had lying around, fits like a glove. 

[e-newbie]

Hi,

I have exactly the same problem. Will probably purchase a new one.

But actually I would like to use an old supply like ou did.

The 8 pin header seems not to be standard. The white wires are +12V I think according to the ATX spec this is -5V!)? The violet one is +5V (standby) ?

Kind regards

[Harry_22]

Hi!
So two identical blocks have the same manifestations of a malfunction. The power supplies worked properly, but at some point they began to “deteriorate”.
This may mean that the parameters of some element have changed catastrophically. Electrolytic capacitors are most susceptible to this, especially if they are installed near a heat source.