Troubleshooting / restoring Sun SS10 PSU - what next?

Hello all,

So I have recapped a few power supplies for older 32 bit Suns (ex: IPX, SS20) with success. No odd behavior, machine works as expected. However the SS10 PSU (Sony APS-39, SUN 300-1081/300-1255) is giving me fits. I have 3 total of these, and out of them only 1 seems to result in a stable machine. The behavior is quite strange - the machine panics right at soft shutdown/powerdown. After troubleshooting nearly everything else in one of my systems, I finally figured out that the problem follows the other 2 PSUs and there is 1 “good one”. All 3 PSUs “work” in the sense of the machine powering on and running. It’s just at final poweroff/shutdown that 2 of the 3 result in a panic.

It seems like the issue could be some (non-electrolytic capacitor) component that’s gone bad in two of them, but not the “good” one ? If this is the case - what component(s) would you all recommend looking at next ?

Here are the pinout/voltages:

I don’t think that looks too exotic. Anyone have an idea of a modern alternate PSU that I could adapt to this ? I’m willing to sacrifice the wiring harness to build a replacement if possible.

Thanks for any ideas.

For a too-long epic story of success in adapting a modern PSU to drive an SS10, see Watts Up, Doc? | Retrocomputing with 90's SPARC

Holy moly - that’s literally the kind of thing I was looking for. Looks like you hit a wall at the end though. Did you ever get this working ?

Seems like this PSU has just enough quirks to make it close to a fools errand to replace :confused:

I did manage to get the main PCB of the APS-39 separated (lots of desolder gun work) and everything recapped. But like I said - it seems like there might be some other component that’s failed and I don’t know what to look at/test next…

EDIT: I see that you actually did get it working. If I were to try to undertake this would you be willing to go back and forth in email for any help ? I can certainly make a dontation to you or charity of choice. Thanks.

Kerp going to the final episode of the story.

It was a success, as you can see from the penultimate episode at Watts Up: Back in the Game | Retrocomputing with 90's SPARC

I never did complete the soft-power-on/soft-power-off extra circuitry though.

I’d be happy to help by email, if you can source a TDK NV1 350 PSU.

Much appreciated. I don’t see a way to PM people on this forum so I’ll just put mine out - you can send me something to get a thread started:

brandon AT burn DOT net

Click on someone’s avatar or name, and the pop-up includes a Message button.

Hmm, is there some limitation for “newer” accounts / low posts/activity ?

Here is what I get for you (and I am logged in). I tried this in Safari as well as FF.

Hmm - PM sent! Hope that helps.