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SGI Personal Iris Troubleshooting Guide

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SGI Personal IRIS power supply label (jan-jaap)
Label of the original Personal IRIS supply: L&H Research CM-E2348A, SGI part 9430801, 350 W, +5 V at 45 A, +12 V at 9 A, −12 V at 2 A (photo: jan-jaap)

Fault-finding on the SGI Personal Iris, from the sgistuff.net reference pages, SGI's IP10 board schematic, and owners' reports on the IRIX Network forum.[1][2] The most useful tools are a serial terminal on the console port and the four status LEDs at the back of the E-module.[3][1]

Status LEDs (4D/20 and 4D/25)

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The IP6 and IP10 CPU boards report power-on test failures on four LEDs visible from the back of the E-module (* = on, o = off):[1]

IP6 and IP10 status LEDs (sgistuff.net)
LEDs Test that failed
*ooo DUART (serial controller)
**oo Walking bit memory test
***o Memory address uniqueness test
**** Graphics
*o*o Interrupt mask

[1]

Serial console

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Connect a terminal or PC at 9600 baud, 8 data bits, no parity, 1 stop bit, with XON/XOFF; one owner used a straight-through cable. The power-on diagnostics report on the serial console even when there is no picture.[3]

No sign of life

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If nothing happens at all, with no fans and no LEDs:

  1. Check the power cord and the power switch wiring. The supply has no soft power control: with mains applied and the switch on, its +5 V and +12 V outputs should simply come up.[4]
  2. Check the two fuses in the supply: one on its small daughtercard, the other beside it under a blue plastic cap.[5]
  3. Measure the outputs at the supply's connectors against the label: +5 V, +12 V and −12 V. The colour code on the supply side is white +5 V, orange +12 V, brown −12 V, green ground, red and black for sense+ and sense−, and blue for the power-fail signal.[5]
  4. If the outputs are missing, the supply has failed. jan-jaap's supply hummed faintly with none of its outputs present.[6]

To test the supply out of the machine, jan-jaap bridged the two power switch wires (white and black) with a jumper; wired like that, it started without difficulty.[4] This leaves mains on the switch wires and the board live; see SGI Personal Iris Capacitor Replacement Guide before working on it.

Replacing a dead supply

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  • jan-jaap replaced his with a Power-One PFC375-4000, which gives 40 A at 5 V against the original's 45 A; he measured 172 W from the wall for a fully loaded 4D/35 without its disk.[6]
  • sgistuff.net describes fitting a Baby-AT computer supply, leaving the sense+, sense− and power-fail wires of the machine unconnected.[5]
  • Raion warns against ATX supplies because of the negative voltages these machines need; GL1zdA adds that few ATX supplies give over 40 A at 5 V.[4]
  • When jan-jaap first powered a spare IP10 board from his new supply, a tantalum capacitor on the board's 12 V rail exploded. The board still worked after the remains were removed, and later with the new supply.[6]

Picture problems

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  • All the status LEDs lit (graphics test failed) on a 4D/20 with GR1.1 graphics: the owner found the diagnostics passed except graphics, and the PROM variable gfx read dead (No keyboard). He suspected the GR1.1 board needs a keyboard attached before it gives a picture; a GR1.2 board in another machine, booted without a keyboard, showed the same messages but still brought up the PROM on screen.[3]
  • jan-jaap describes two video outputs on a 4D/25: RGB on BNC connectors and a VGA-style port marked COMPOSITE. Both carry sync on green, so the monitor has to accept it; he recalls the VGA-style port reaching about 1024 × 768 and the BNC outputs 1280 × 1024.[7]

PROM password and boot settings

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  • A PROM password set by a previous owner blocks the command monitor. It can be cleared from IRIX as root. Without a working IRIX, jan-jaap suggests unplugging the 10-wire flat cable from the small board with the reset switch, which carries a 93C56 serial EEPROM; the machine should then reach the PROM, though without its system ID. Plug the cable back in without switching off, and set a new password. He was not sure whether resetenv also clears it.[7]
  • bootmode in these older PROMs sets the start-up behaviour: c runs the power-on diagnostics and boots the kernel automatically, m runs the diagnostics and stops at the command monitor, and d goes to the command monitor without diagnostics or clearing memory.[8]
  • One owner's IP6 machine booted by hand but not automatically. He traced the same fault on an R3000 Indigo to a disk label written by the IRIX 5.3 boot CD's fx; a fresh disk labelled by the installed system's fx booted automatically.[8]

Overheating (4D/30 and 4D/35)

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The IP14 and IP12 boards need their CPU fan, on the E-module cover and powered from the connector at H14. sgistuff.net warns that without it running the processor will overheat and fail.[1]

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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 Gerhard Lenerz, "Personal Iris", sgistuff.net, sgistuff.net (retrieved 22 October 2026). IP6 and IP10 status LEDs, CPU fan.
  2. ↑ Silicon Graphics, IP10 CPU board schematic 032-8029-001, 1989 (File:SGI Personal IRIS IP10 CPU Board Schematic and Bill of Materials (032-8029-001).pdf).
  3. ↑ 3.0 3.1 3.2 "Personal IRIS 4D/20 error LED meanings", IRIX Network forum, posts by Xav101 and robespierre, 27 to 28 July 2022, forums.irixnet.org/thread-3618.html.
  4. ↑ 4.0 4.1 4.2 "Personal IRIS won't start", IRIX Network forum, posts by GL1zdA, jan-jaap, Raion and weblacky, 25 to 26 August 2021, forums.irixnet.org/thread-3078.html.
  5. ↑ 5.0 5.1 5.2 Gerhard Lenerz, "Personal Iris PSU replacement", sgistuff.net, sgistuff.net (retrieved 22 October 2026). Fuses, colour code, fitting a Baby-AT supply.
  6. ↑ 6.0 6.1 6.2 "Introducing: my Personal IRIS 4D/35", IRIX Network forum, posts by jan-jaap, 23 September 2019, forums.irixnet.org/thread-1468.html.
  7. ↑ 7.0 7.1 jan-jaap, in "New Box- Personal Iris 4D/25 - Prom Password?", IRIX Network forum, 3 December 2018, forums.irixnet.org/thread-740.html.
  8. ↑ 8.0 8.1 "Correct PROM settings for Personal IRIS IP6...", IRIX Network forum, posts by mapesdhs and johnnym, June to July 2019, forums.irixnet.org/thread-1299.html. bootmode values quoted from SGI's IRIX Admin: System Configuration and Operation.


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