Re: Delta DPS-400GB-1A Troubleshoot (xserve)

A couple of more findings:

* the MOSFET driver IC1 (TC428) has steady low at IN_B and OUT_B
* the transformer T3 through which the mosfet driver is triggered has no signal on either the primary nor the secondary side (confirmed with scope)
* the relay is clicking immediately when AC power is connected (i forgot to mention this in the last post)

a separate question for those who worked with this PSU before:
* did you need to connect the fans to make it power up (there could be some protection...

Re: Delta DPS-400GB-1A Troubleshoot (xserve)

I'm also experiencing problems with this power supply.

However, much to the difference to the original posters, I think the small switching power supply for supplying the control logic is working fine. I get the 'buzzing' sound, and I can clearly measure a stable and clean voltage on the capacitors on the secondary side of the small transformer.

Just for the sake of completeness, I've replaced all capacitors on the board, with the exception to the large primary filtering cap (390uF / 450V) and the 1000uF...