Troubleshooting an Indigo2 High Impact

[joshc]

I have an Indio2 High Impact on the way which apparently doesn't turn on. This is what the seller has said so far

Just a few words on history of machine which may aid diagnostics... it initially would not work when I acquired it however after applying isopropyl to riser CPU and gpu contacts allowing to dry then reseating it booted fine and I installed irix.
It was then in dry heated storage for coming on to a year and would not boot at all after this period. I checked CPU and mid plane contacts applying pressure as per user manual but could not get it to boot.

There's no sign of damaged caps on main board or gpu but I've not opened psu to check if any have blown there.

I tend to think its psu issue or perhaps a poor contact somewhere between CPU/mainboard/gpu (I've had some curios problems with twin slot 1 cpus which both work but machine is only stable if they are in specific slots and heard of CPU working in one indigo but not in another etc!

Where should I start with this?

 

[Elf]

Some of the information here may be helpful in allowing you to test the power supply outside of the machine: https://forums.sgi.sh/index.php?threads/indigo-2-power-supply-basics.111/

Many of these old PSUs certainly are becoming failure prone and would be a good first avenue of investigation.