DELL Z930P-00 SLOW start

[ktmmotocross]

Hello
Have this DELL Z930P-00 server power supply, that when connected to power, not start. i hear BZZZZZZZ sound and after about 10seconds relay flips and main power works. when i disconnect it from power and reconnect it, it start imediatelly.
looks like bad capacitor. i buy cheap ESR meter from aliexpress but it show me that all capacitors is ok.

attached picture where i hear that sound

[PeteS in CA]

Re: DELL Z930P-00 SLOW start

Does the 5V (or 12V) Standby voltage come up immediately or take 5-10 seconds to come up?

[ktmmotocross]

Re: DELL Z930P-00 SLOW start

I dont know where is stand by voltage making, because i dont have schematic, but i measure two smaller caps and few seconds have 0.0V than 1.5V and when PSU start it have 16V

[ktmmotocross]

Re: DELL Z930P-00 SLOW start

i found 3.3V on output pin. when slow start it goes 0.35V than 0.6V and slowly rise to 0.8V and then PSU start and it goes 3,3V

[sam_sam_sam]

Re: DELL Z930P-00 SLOW start

i found 3.3V on output pin. when slow start it goes 0.35V than 0.6V and slowly rise to 0.8V and then PSU start and it goes 3,3V

What voltage do you have at the optic sensors when you start up the power supply does it take a little while to come to voltage I had a feeling that there might be a problem with that capacitor just for shits and giggles if you have one replace it and see what happens next if gets better or it stays the same

[ktmmotocross]

Re: DELL Z930P-00 SLOW start

can u point me on my picture what capacitor and what "optic sensor"do u mean?

with that optic sensor u mean optocoupler?

[ktmmotocross]

Re: DELL Z930P-00 SLOW start

replaced that two marked capacitor on my picture but it acts the same

[Rainbow]

Re: DELL Z930P-00 SLOW start

There's a 22uF/35V SMD capacitor on the vertical control board that often goes bad (because of the heat from resistors) and the PSU dies completely.

To avoid desoldering the vertical board, remove the bad capacitor by rotating it using long pliers (the legs will break in the plastic bottom).
Then solder new capacitor from the other side of the vertical board. The big copper plane on the lower half of the board is GND and goes to capacitor negative pole. The positive pole goes to a short trace on the right side, just above the GND. Check using a meter to be sure that it's connected to the original capacitor pads.