Re: Compaq Deskpro 386s PSU

SHE'S ALIVE

Thanks everyone for the tips. I bought a pack of 10 on-semi from ebay (i think just 100V ones sorry stj) and replaced the diode.

I also went around and reflowed, with loads of flux, every solder joint around the leaked area. Then doused the whole thing rather liberally in PCB cleaner and let it dry. Will probably pop it back out and give it a proper deep clean with distilled water/detergent, IPA soak and cleaning with a soft toothbrush at some point, but it's alive!

Thanks again everyone!

Re: Compaq Deskpro 386s PSU



You were onto something here, once I popped the 3040 out I tested it on diode mode of my ol multimeter. It was fine. So I decided if it ain't broke don't fix it and put it back in.

I resoldered every connection around where there was an electrolyte leak of one of the old caps (and what prompted me to recap in the first place) and even through my respirator I noticed that wonderful fishy smell of burnt electrolyte. As a side note, I guess I was wearing it wrong. But that told me there was still electrolyte around making my...

Re: Compaq Deskpro 386s PSU



You've done this before! There is a Schottky barrier rectifier (SBL3040PT) in which all 3 pins are essentially shorts to GND. Will keep probing but that defo screams of being dead....

Re: Compaq Deskpro 386s PSU

So it's now had it's second recap with the above suggested caps and still nada so I fear this may be a silicon problem.

I'm not sure if this happened before the second recap, but when it's turned on, there are no signs of life except for the fan trying to spin up. It spins for about a second then stops for a couple. Rinse and repeat ad infinitum. I don't own an oscilloscope to go deep probing, and I don't know the pinout of the custom board connector. Next step is to trace every line out and work out where they're all going. It's...

Re: Compaq Deskpro 386s PSU



It does a lot thank you. I have got the caps on order, I took your advice and ordered those chemi-con families (serendipity meant I ordered the LXY series for the cap in which the data sheet requested that series as a replacement. I'd somehow managed to blank that). And I went for Nichicon GX series for the primary smoothing caps as I made the bold assumption (as I'm more solder monkey than electronic designer) that ripple only really matters on the secondary side.



I hope not. It's hard enough finding adequate...

Re: Compaq Deskpro 386s PSU

I've seen those families floated a few times for a few different things, are they generally suitable replacements for most things that age? If that's the case my life just got a bit simpler thanks.

Any families in particular for the Rubys or Nichis? I have some Nichi PW(M) in there already. And for the primaries, does the family still matter there? I see Chemi-Con KMQ series on RS.

Edit: just saw your edit, thanks for the extra detail!

So after 30 years, it finally happened and the capacitors leaked. I've tried a recap with Kemet's as the primaries and a mix of nichis and Wurths everywhere else, and it won't boot. No fans spinning. No LED activity. I've double and triple checked the soldering and negi-lead orientation. No catastrphic trace destruction and instead more minor blistering at some points. Thus I can only assume its ESR.

Now the main issue here is these are 30+ year old capacitors. The internet wasn't in the best condition in 1989 so I'm really struggling to find any mention of most of these caps at all...

Re: New Members - please post your introductions here

Hallo, I'm the compaq guy and my interest is in vintage Compaq deskpro systems.

I'm here as like many of you, those systems are old and rickety and often need recapped, and datasheets are hard to come by...