SGI Onyx restoration
RE: SGI Onyx restoration
All cleaned up...and look at that fan!

[Image: FOABxU1.jpg]

[Image: mnTvJeq.png]
Jurassic Technologist

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03-21-2019, 09:35 PM
RE: SGI Onyx restoration
Couple of hints:

* The Dallas RTC NVRAM battery is almost certainly dead. There are two: one on the system controller, one on the IO4. Normally in SGIs, the system serial number is tied to the chassis, not a PCB like a CPU or IO board, especially not in a system that can have many. So the system controller is "master" of the serial number and a few other things. The first IO board contains the PROM environment variables, and a backup of the system ID so you can replace the Dallas on the system controller if it runs out without losing the system ID. You will have to mod the Dallas chips with CR2032 cells or replace them. The IO4 is an extremely thick PCB and I was never able to desolder anything from it, so I did the CR2032 mod.

* There are two PDF copies on Ian mapleson's SGIdepot of the "Onyx/Challenge Diagnostics Roadmap", the older rev is a scanned printout. This one has a chapter on how to manually program a system ID into  the system. This procedure only works if both Dallas chips are blank.

* That blower is something indeed. Don't put your fingers or anything else you value inside it  Wink If the Onyx throws a "blower failure" the problem is probably not with the blower but with the tacho signal or the wiring. The sound is rather "metalic" for lack of a better word. It's also really loud in "fast fan" mode.

* There was a recall on the OLS (the big 48VDC power supply on top of the chassis in the photo) at some point because they were deemed a fire hazard:  There were several versions of the OLS around and only the last revision of the IR capable OLS (2400W, 48VDC @ 50A, part# 060-0120-001 Rev A) is "safe". Then again, you probably shouldn't leave a 25 year old system capable of arc-welding currents running unattended in the first place.
(This post was last modified: 03-22-2019, 09:00 AM by jan-jaap.)
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03-22-2019, 08:40 AM

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