[Dylanear]

So I have an Indigo2 on long term loan from an acquaintance. It has no hard drive, but last I powered it on it started up just fine, made the chime, I got video and could interact with the command prompt, etc. So, here I am, probably 3 or 4 months later and I plug it in and hit the power button, the fans kick in, no LED, not even a flash and it just stays like that. I removed the RAM, CPU, and graphics card and mid plane and reseated them all. No difference. 

It's a Zytek power supply. What do I need to do to test the power outputs from the power supply? If I just remove it and plug it into the wall will I be able to test all the various power supplies, 12v, 5v, etc with by just knowing the pin outs? Or does something need to get jumped for it to give the power it would to a working system?

Anything else to try short of investigating the power supply? So annoying, it worked fine for many months after it was loaned to me. I just spent over $200 Canadian on a drive sled and 9gb scsi drive for this thing and now it won't power on? Oh, vintage computing ain't a hobby for the faint of heart or those easily annoyed. :(

[Raion]

All SGI PSUs require proper load to really "test". They do not enter regulation at zero.

That being said, the AC side of the PSU should power up if disconnected and with a sufficient load on each rail (especially the 5V) you should be good. I have write-ups on this coming eventually, but it will be a long while so don't get your hopes up. It's a "ground-to-stop" PSU, so if it's disconnected, hence it should start up.

[weblacky]

Impact-ready PSUs require a special pown-on sequence, Indigo2 PSUs that lack the IMPACT board, heavy blue ribbon, power connector will power on from wall connection alone. But without some load their voltage fluctuates.

However your posted symptoms are the same as this post...it's the PSU: https://forums.irixnet.org/thread-957-page-2.html

[Dylanear]

This is a Zytek with the heavy blue ribbon.

Yeah. read that thread and considered replying to it rather than starting a new topic. If the mods have an opinion on that, happy to delete this and reply there.

My symptoms don't match the original poster of that thread's symptoms. He has a light.
"no boot chime, power light comes on green in half a second, then no amber or anything else, just stays green."

But my symptoms do perfectly match those described by TriOx:
"In my case the LED never came on at all, but the PS and mid-plane fans ran when I hit the power switch."
and:
"Note, in all cases the symptom was no LED at all and the Power Supply and midplane fans were running, power button couldn't power back down, had to pull the plug to power off."

That does sounds exactly like what I'm getting. But I've pushed pretty good on the midplane after removing, inspecting and dusting it. I pushed down before removing it and there was no real movement to speak of, but the two screws were also holding it in place. I could try reseating the CPU again, but I have it a pretty firm push too.

Good chance it's not the power supply, but this thing will probably need new caps sooner or later, probably sooner!

[weblacky]

I linked it because of TriOx's statement.

I don't reseat things so needlessly (risky, if fully removed then attempt reinsertion). This sounds like PSU, either a voltage drop at turn-on, or time to power good (PG signal) takes too long. I've seen this exact same symptom in PCs with the PG-signal taking too long to stabilize, zombie mainboard with fans only, no post. While SGI's use a fake PG signal it has to actually come on and ramp up. That time factor should still be important.

[Dylanear]

Yeah, I'm pretty hesitant to mess with old hardware if I can help it. And I'm really careful when I do.

So.... I got it working and it was the CPU seating it seems? But not the whole module. Just the hex screws on the heatsync. Hadn't touched those just removed the whole module and put it back, gave it a firm but steady push, screwed it back down. Didn't work.

So I was curious what those hex head bolts did? Weill they were loose-ish. So I have them a snug, but not hard tightening with a 3/16th hex wrench. and plugged it on, hit the button and there was the chime.

Next week I should hopefully have a running system once the drive arrives. Hopefully with a clean install of 6.5 for the Indigo2 R10K, but I guess we'll see what's on there once I get it. Worse comes to worse and I can do an install over the net or something. Just setting up the server always looked a bit tricky without another SGI around.