[noleex]

No there isn’t a printout

[sunray]

No there isn’t a printout

Okey.

First such boards can be very very difficult to repair even if you have the schematic and even if you are the designer of it that I can tell since I am such a guy and have been there many many times

Since something turns the red LED on which indicates error then it could for example be a circuit that makes it red first and then the CPU should make it green so what makes the CPU not run.

- Power rissue on the motherboard
- Reset asserted
- Oscillator not working

I would start and check that all oscillators are working, without them things will not work

How much do you know about HW?  Perhaps drop some nice photos of the board if you are unsure

[weblacky]

Well I guess if it's a KISS principle, if the CPU module works in another O2...then it's not the CPU module itself in short or causing the issue, same with all other modular components (PSU, RAM, PCI-Riser, Add-ons, HDDs, etc).

Then you'd be left with power (my #1 thought, by component failure), logic/commands signal issues, or PROM/Firmware corruption - (something I've brought up as a concern since O2 PROMS haven't been released in years and are some kind of FLASH technology...it's hard to know the retention life since it was designed to be reflashed every so often to reset this interval? Not that I give a huge amount of thought to this possibly, non-existent, issue).

Obviously once you get into firmware, you're pretty much done. If one knew about general Mainboard system initialization (I don't) you might be able to somewhat determine the logic of start-up in a gross way.

But the above point it well taken, since there is an Error indicator, some board logic MUST be happening. Though I've not seen any console serial boot output posted on this thread. I'm unsure when firmware console output occurs in an O2, but I was lead to believe that even PROM-level diags DO show up in console output. So since that hasn't been checked yet, it would seem to be the best place to start to verify that the serial console doesn't give any output (or anything meaningful) during hardware startup.

All SGIs that I've seen do this start in firmware and it's the first goto for all of us.

Read the O2 manual and construct a FULL NULL-modem cable and verify console output during power-on. If none is produced, well then it's a basic/early issue the system is experiencing. But if luck's on your side, you might get a sliver of output that says what's it's not or where is was before failure during power-on.

[noleex]

I will check that with the second board that is not running but the first one has absolutely no serial output, but I‘ll double check this afternoon ;-)

[soviet]

You can try cleaning the motherboard a good scrubing hot water and soap, this miracusly have fixed some isa boards from me in the past.
Also inspect it using a microscope to check for things like a small short.

[dexter1]

You might want to check out an old thread of mine fixing an O2 from near-death:

https://forums.irixnet.org/thread-39-pos...ml#pid9014

So try starting it with the jumper installed to reset the prom variables. If that doesn't work, consider replacing the Dallas RTC Chip DS1687-5