Delta DPSN-525AP Power Supply Repair

[jayjr1105]

Hi all, this power supply is for a Cisco POE ethernet switch. It's 525watts and puts out two rails, 50v for the POE and I think 12v for the main logic board. When powered on, the 50V rail seems good but I get less than 1 volt on all the red wires coming out of the 14 pin connector (14 pin connector is only red and black wires).

Any recommendations to troubleshoot? I can't find a pinout or schematic but I see that there are basically 2 rails distributed.

https://prnt.sc/m5lwqq

http://prntscr.com/m5m6uh

[PeteS in CA]

Re: Delta DPSN-525AP Power Supply Repair

I'm not familiar with this P/S, but it looks to me like there is a PFC stage, followed by two separate, individually regulated inverters (probably synced). So the fact that the -53 works indicated that the PFC works, but the 12V circuit is not, So your focus will need to be learning why.

I'd start first by looking at whether the 12V output is shorted. If it isn't and the output is literally zero volts, you need to find out why the controller is not switching. If the controller is on the primary side, you can't use a grounded oscilloscope.

[R_J]

Re: Delta DPSN-525AP Power Supply Repair

Start at the missing 12 volt output and trace the secondary circuit back. The voltage will come from diode off a transformer secondary, if there is no voltage on that diode, check the primary side to see how it operates, ie does it have proper voltage to the switching fet/s, is the drive ic getting vcc and is being turned on.
I could not find any schematic or even good pictures of the solder side.

[jayjr1105]

Re: Delta DPSN-525AP Power Supply Repair

I'll try to get some high res photos on the back side when I get home.

[jayjr1105]

Re: Delta DPSN-525AP Power Supply Repair

Here's a good shot of the back

https://i.imgur.com/27K5XeK.jpg?1

[ktmmotocross]

Re: Delta DPSN-525AP Power Supply Repair

try to heat up capacitors and checking for output voltage