UPS PSU power loss

[legsElectric]

Hi all

I've got a server-rack style PSU that powers a UPS on our 22kv switch gear, that has thrown up a rectifier fault and no longer puts out any DC voltage. It's not an expensive item but the lead time on a replacement is long so if there's any way to affect a repair it'd be a big win. I'm only a regular, albeit handsome and modest, sparky so my knowledge of it's inner workings are fairly limited. But I do have access to a electronics lab and some test gear so I'm hoping to do a miracle fix and look like a legend in the eyes of upper management.

Current status is:
   - General Fault and Rectifier Fault indicated by the UPS controller LEDs
   - Solid green Power LED (pg.10 of the attached manual) on the module front panel
   - Solid red Alarm LED on the module front panel, regardless of whether it's racked into the panel or sitting on the lab bench
   - 12Vdc cooling fan working
   - 0Vdc on the main output
   - no obvious damage or scorching, and the electrolytic caps aren't swollen

I'm not sure where to go from here so I'm hoping for a bit of guidance. Thanks in advance!

[u666sa]

They are 100% repairable. Easy $50 to $150 I tell you, if you doing these repairs on regular, think $500 and up a day, free money.

This particular cap looks bloated to my eye. Plus you saying rectifier fault, that means voltage isn't as straight as it should be. I say pull all 3 caps, check them, replace as needed. But in your case, since you don't have LCR meter, you just replace all 3 caps. Caps can have larger capacitance, just make sure voltage is at least that what those caps are and they fit in.

Where to get caps? Here I have a store, I can run to it and buy caps. In larger city I would have pickup points for what is equivalent to digikey and farnell. Plus I could pick them in equivalent of amazon and have them delivered to pickup point for free. Your options depend on what is available in ausie land. Be careful with ali, sometimes large caps are fake, you open them up and inside is a small cap.

[Poroit]

G'day legsElectric,

I have found the attached very useful when repairing SMPS.

Haseeb Electronics also has a lot of helpful videos.

Just be careful when you pull it apart that you sketch or photo where all the component insulators are mounted.

Typically a multimeter and a ESR tester is all the test gear you need.

I use Element 14 or RS in Oz for components.

[legsElectric]

Awesome, thanks a lot!

I have found the attached very useful when repairing SMPS.

Haseeb Electronics also has a lot of helpful videos.

That's just the kind of thing I was looking for, a bit of light reading for the weekend haha

This particular cap looks bloated to my eye. Plus you saying rectifier fault, that means voltage isn't as straight as it should be. I say pull all 3 caps, check them, replace as needed.

There's a blob of silicone on that cap that probably makes it look that way but I'll pop them all off and check them over, thanks