BeQuiet Dark Power Pro P10 550W PSU: Missing 5V Standby

[peter21]

Hi there,
a friend of mine gave me a BeQuiet Dark Power Pro P10 550W PSU.

The problem: The PSU simply switched off during operation and never came back on.

My observations / measurements:

I opened the housing and checked for obvious damage -> negative. Visually, everything seems fine.

Lowcost power supply tester (China):
No result. The power supply does not turn on and the tester keeps off

Next, I measured the 5V standby line (pin 4) on the ATX connector.
Result: Not present (!).

Obviously this seems to be the problem why the power supply no longer comes on.

Following some pictures...

Top view



Bottom view


The hotspot seems to be coming from this candidate:

TNY274280

Datasheet: http://bg-electronics.de/datenblaett...TNY274-280.pdf


Pin 5, 6, 7 and 8 are connected - as per datasheet
What I noticed is a connection between Pin 1 [EN/UV] and Pin (5, 6, 7, 8) [Source].
Could this be the problem? I carried out the check in the built-in state.

Can anyone give me a tip on how I can further investigate the error?

If needed: Here are some HQ photos of this PSU from a review site: https://www.techpowerup.com/review/b...10-550w/4.html

Many thanks in advance
Peter

[harp]

Next, I measured the 5V standby line (pin 4) on the ATX connector.
Result: Not present (!).

Disconect from power mains, wait to discarge, and do resistance measurement on purple wire (+5vsb), if is shorted the most likely is shorted diode.