SGI: Hardware

This is the kind of behavior you get when the PSU is going into overcurrent protection because it's plugged into a short. If they repaired the PSU, presumably they tested it was working before they sent it back. That suggests to me the problem is somewhere else in the machine.

If it still shuts down with the graphics and drives removed, I would start by looking at the -12v rails on the mainboard. A shorted tantalum capacitor can hide here since the whole -12v load doesn't normally draw enough current to cause a catastrophic breakdown of the capacitor (explosion/fire) like you would get on the +5 or +12v rails, but will still cause the PSU to shut down. Measure the resistance between the -12v PSU pins on the mainboard and ground. The load should be less than an amp (>12 ohms). If it's anything under 10 ohms, there's likely a problem. I'm willing to bet you'll find it's under 1 ohm (e.g. a full short).

If they repaired the PSU, presumably they tested it was working before they sent it back.

That would be a quite reasonable assumption to make - however I'm not sure that's the case. I got this line in one of the emails from the company:

"We have managed to repair it but we can’t actually test it here – you will need to do that at your end."

Mkayyy... I mean I'm sure they tested it in so much as they were able to verify that it should work and not actually blow up my computer?!

Anyway - the main reason I sent the supply off to a company to look into it as I basically know nothing about electronics. So being able to test rails, etc on the board myself is just not within my skill set.

On the plus side a friend local to me does, it turns out, have an R10 Impact Indigo2 as well so I think he's up for a bit of a component swapping session one evening to work out if indeed it is still the power supply, or whether it's something else like a component on the mainboard.

As another follow up I did a lot of searching through Nekochan to find out about what power supplies are compatible and what are not so that when I go to my friends place, I can at least verify if the PSU in his Indigo2 is suitable to test in my system or not. Found an extremely helpful / holy grail kind of email that breaks it down quite nicely which I thought might be useful to be referenced here, in case anyone goes through the same fun as me:

There are five power supplies available for an Indigo2:

Part number: 9430814
Suitable for Extreme, XZ and XL graphics on R4400 and R8000 machines.

Part number: 060-8001-xxx
Suitable for single-head (Solid, High or Max) IMPACT graphics and
dual-head Solid/Solid IMPACT graphics on R4400 machines. Can also
be used in place of 9430814.

Part number: 060-0021-xxx
Suitable for dual-head (Max/Solid, High/High or High/Solid) IMPACT
graphics on R4400 machines. Can also be used in place of 9430814
or 060-8001-xxx.

Part number: 060-8002-xxx
Suitable for single-head IMPACT graphics on R10000 machines.

Part number: 060-0027-xxx
Suitable for dual-head IMPACT graphics on R10000 machines. Can
also be used in place of 060-8002-xxx.

On the plus side, if I never manage to get this PSU fully repaired and decide to source another second hand one, I at least know I can use the cheaper 060-8002-xxx type one as I've no intentions to 'double head' my Indigo2 and just plan to stick with the single HighIMPACT card I currently have. The supply I own and sent off for repair is the 060-0027-xxx type suitable for a double head configuration.

Hoping someone will read this and be able to advise.

I do actually have a second Indigo2 but it's an R4400 non-IMPACT model so only has the 9430814 power supply. So that I can simply confirm the power supply is the component to blame, can anyone answer if it is safe for me to remove all expansion cards / drives, etc to absolutely minimise the load for the supply and fit that supply to my non-working R10K Indigo2? I figure the connections to the mainboard are the same and that the blue extension cable out of the supply is only there to provide additional power for the IMPACT cards. So surely with no graphics card fitted the PSU should have enough juice to power up an R10K and I can just verify it's alive using the serial port?

This would save me having to drag my system over to my friends house for a fault finding session.

Thanks in advance.

Finally managed to get my system over to a friends house this evening as he has an Indigo 2 IMPACT. We were able to confirm that the power supply is still not fixed so will be going back to the company to look into again.

Thanks prime for helping out!

Well, I rather hope they will pay for postage back and forth.

Somehow I doubt that. But we'll see. I'm about to leave the country for a week and a half for work so will have to look into this again when I get back.