Jump to content

SGI Challenge M Capacitor Replacement Guide

From RetroTechCollection
SGI CHALLENGE M power supply screws (108-0130-001 Figure 2-6)
The power supply at the rear left of the chassis, held by two screws at the back and two at the side (SGI, 108-0130-001 Figure 2-6)

The SGI Challenge M uses the Indigo² chassis and power supply, and SGI treats the supply as a single replaceable part: its R8000 upgrade swaps the whole supply and gives no component list.[1][2][3] No capacitor values for the Challenge M have been published by SGI or by owners. The values and rebuild advice that owners have published for the teal Indigo² supply are in the SGI Indigo² Capacitor Replacement Guide. Below are the points specific to the Challenge M, and a way to record your own supply before ordering parts.

Warning: the power supply runs from the mains. Unplug it, let the input capacitors discharge and check them with a meter before touching the boards.

Which supply

[edit | edit source]
  • SGI's revision S and later supplies are mechanically the same as earlier ones but give 3.45 V on the nominal 3.3 V rail. They are needed for the R8000, the 200 MHz R4400 and the 133 MHz R4600, so a POWER CHALLENGE M must keep a revision S or later supply after any repair.[2]
  • The revision letter is marked on the side of the supply.[4] The supply part numbers owners have reported for the Indigo² are listed in SGI Indigo² Capacitor Replacement Guide#Which supply; check the label on your own supply against them.

Other capacitors to know about

[edit | edit source]
  • On the R8000 CPU module, SGI says there are several capacitors on the back of the module that help control its internal clocks, and that the module will not work if one of them is damaged. It warns against setting the module down roughly, scraping its underside on the chassis or hitting it against the 3.5-inch drive bay, and against using an ohmmeter on it. SGI gives no values or types for these parts.[5][6]
  • The audio-board tantalum failure reported on Indigo² machines cannot occur on a Challenge M, which has no sound hardware.[7][3]
  • For the CHALLENGEvault M, forum member jan-jaap says the vault uses the same power supply as the Indigo²; SGI fits a resistive load unit in drive position 6 to balance the supply when fewer than six disks are installed.[8][9]

Removing the supply

[edit | edit source]

SGI's procedure from the R8000 upgrade instructions:[10]

  1. Shut down, unplug the machine and take off the front bezel and top cover; see SGI Challenge M General Maintenance#Opening the case.
  2. Remove the 5.25-inch drive tray and any expansion boards.
  3. Undo the four screws that hold the supply: two on the back of the system and two on the side.
  4. Disconnect the supply cables.
  5. Slide the supply forwards about 6 mm (1/4 in) and lift it out.

When refitting it in an older chassis, the two tabs under the supply may need bending outwards by about 2 to 3 mm before they will engage the U-shaped slots in the chassis floor.[11]

Recording your own supply

[edit | edit source]

Before ordering parts, photograph both sides of each board and write down, for every electrolytic capacitor: its designator, capacitance, voltage, temperature rating, series, diameter, height and lead spacing. Note the supply's part number and revision letter from its label as well, so that the record can be matched to other owners' reports of the same supply. The procedure for the recap itself, the choice of replacement parts and the first power-up through a bulb current limiter are in the SGI Indigo² Capacitor Replacement Guide.

Checks after the work

[edit | edit source]

Refit the supply, power on and watch the front LED go from blinking green through amber to green as the power-on tests pass, reading the PROM messages on a terminal on serial port 1.[12] Then check the processor and memory with hinv -v from the Command Monitor; see SGI Challenge M Troubleshooting Guide#Checking the hardware with hinv.[13]

[edit | edit source]

References

[edit | edit source]
  1. ↑ Gerhard Lenerz, "Indigo 2 / Challenge M", sgistuff.net, sgistuff.net/hardware/systems/indigo2.html (retrieved 22 October 2026). Specials section "Challenge M": an Indigo2 without the graphics option, otherwise the same machine.
  2. ↑ 2.0 2.1 Silicon Graphics, POWER Indigo2 and POWER CHALLENGE M Upgrade Instructions, 108-0130-001, 1994, section 1.3, p. 1-2 (File:SGI POWER Indigo2 and POWER CHALLENGE M Upgrade Instructions (108-0130-001).pdf). Revision S power supply.
  3. ↑ 3.0 3.1 SGI, 108-0130-001, section 2.1, p. 2-1. Upgrade steps: power supply, CPU module and system board replaced; audio subsystem moved on Indigo2 systems only.
  4. ↑ SGI, 108-0130-001, section 2.2, p. 2-3. Revision marked on the side of the power supply.
  5. ↑ SGI, 108-0130-001, section 2.1.1, p. 2-2. Capacitors on the back of the R8000 module; no ohmmeter.
  6. ↑ SGI, 108-0130-001, section 2.4, step 5, p. 2-15. "Several critical capacitors on the back of the CPU module."
  7. ↑ "SGI Indigo2", Wikipedia, revision of 22 June 2026, section "Challenge M", en.wikipedia.org/wiki/SGI_Indigo2. No graphics or sound hardware.
  8. ↑ TriOx, jan-jaap and GL1zdA, "Challenge Vault M", IRIXNet forums, August to September 2019, forums.irixnet.org/thread-1445.html.
  9. ↑ Silicon Graphics, CHALLENGEvault M Owner's Guide, 007-2155-001, 1993, p. 21 (File:SGI CHALLENGEvault M Owner's Guide (007-2155-001).pdf). Resistive load stabilisation unit.
  10. ↑ SGI, 108-0130-001, section 2.3, steps 1 to 11 and Figures 2-2 to 2-8, pp. 2-4 to 2-9.
  11. ↑ SGI, 108-0130-001, section 2.4, step 3, note, p. 2-14.
  12. ↑ Silicon Graphics, Indigo2 Workstation Owner's Guide, 007-9096-050, p. 127 (File:SGI Indigo2 Workstation Owner's Guide (007-9096-050).pdf). Power-on LED sequence; ASCII terminal on serial port 1.
  13. ↑ SGI, 108-0130-001, section 2.5, p. 2-19.


Retrieved from "https://retrotechwiki.com/index.php?title=SGI_Challenge_M_Capacitor_Replacement_Guide&oldid=29474"