Recapping Sun SPARCstation IPC Power Supplies

[glitch]

The recent pick-up of Sun hardware included a bunch of "lunchbox" form factor machines (SPARCstation IPC and IPX machines). All of the IPX machines worked, but both IPC machines had dead power supplies. Opened them up to find a bunch of leaking Chemicon and Elna capacitors. I don't know if this is a capacitor plague/counterfeit thing (both are good brands, and were rated 105C) or what. Anyhow, I wrote up the recapping process here:

http://www.glitchwrks.com/2017/07/24/ipc-recap

I've included a list of part numbers with original capacitor values, as well as a cross-reference to current production Nichicon substitutes. Both supplies work fine, and both SPARCstation IPCs are now functional Here's a pic of the inside of the supply, after recapping:



I went ahead and replaced all capacitors except the line-side filter cap. The smaller ones looked OK, but I figured I might as well do all of them, since I had it open, and capacitors are cheap.

 

[glitch]

Just got another IPC of my own and a power supply to repair from someone online, both had very leaky low ESR caps as the first two did. I guess this is just a thing with SPARCstation IPC power supplies!

 

[tipo158]

Is it possible for the power supply to be too far gone to be fixed by just replacing the caps?

I replaced the caps on an IPC power supply over the winter break and it didn't work. Well, it worked for maybe five minutes then went into a mode where it started clicking every second or so. The fan would move in sync with the click. I am a software guy, so this kind of hardware is all black magic and voodoo to me.

I ended up pulling the power supply from my IPX and using that in the IPC. I am picking up another IPX (with the Weitek POWERuP processor) tomorrow. The IPX that I pulled the power supply from has the Dataram memory upgrade, so it will be interesting to have it and the POWERuP processor in the same system.

alan

 

[glitch]

Well, you've at least got a maxed out system from all the parts!

Did you replace the capacitors with the correct low-ESR caps where required? If you used my Nichicon part # list, then you should be working. Did you make sure every cap was in with the correct polarity? Usually they'll explode if not, so that's not too likely.

 

[tipo158]

Yes, I replaced every cap in your list. I double checked and the polarities were all correct.

As I said, it worked for several minutes. I initially didn't realize that the bwtwo would not sync with the display that I was using, but the IPC sounded like it came up. I was looking for a spare cgsix when I heard the HDD spin up and down strangely. Then the clicking started. At one point I saw arc'ing (in sync with the clicking) where a fan screw is very close to a cap, but I moved the cap to avoid the screw and now the power supply just clicks.

I was in the middle of desoldering the new caps to confirm there was no debris, flux, whatever under them when I remembered that the guy had offered me the IPX.

I am putting together an exhibit on the Sun lunchbox systems for the VCF Pacific Northwest in Feb and want to make sure that I have a working example of each one for it. If all else failed, I also have a RDI Britelite IPX that could stand in for the IPX that gave its power supply to the IPC.

 

[glitch]

Did you replace with the same replacements I used, though?

If you had arcing from the can of one of the caps, something may have been damaged further in the circuit. The clicking is generally the power supply coming up, and quickly shutting back down due to an overload or overvoltage. Could've saved itself, could be one of the caps was damaged due to the arcing, hard to tell. The IPX supply will of course work fine in the IPC.

 

[tipo158]

Yes. I took your list and cut-and-pasted each cap into the Mouser web site.

Do you know why the IPC power supplies are apparently more susceptible to failure than the IPX ones? I haven't done a component by component comparison, but to me they look close to the same.

 

[pkhoury]

IPX power supplies seem to be weird. I recapped mine about a year ago. It worked, then it stopped working while showing it off at one of our club's quarterly meetups. Then it started working again when I brought it home, and hasn't failed since.