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SGI Indigo² General Maintenance

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SGI Indigo2 front (Rules666)
Front of a teal Indigo². The front cover snaps down to reach the bezel and the drive bays (Rules666, CC BY-SA 4.0)

Routine care and service procedures for the SGI Indigo², from Silicon Graphics' Indigo2 Workstation Owner's Guide (007-9096-050) for the teal machines and the Indigo2 IMPACT Workstation Owner's Guide (007-2849-004), with notes from owners on the IRIX Network forums.[1][2] SGI expected owners to replace the memory, graphics boards, CPU module, CPU baseboard, power supply and drives themselves, and its guides go no further than those parts.[3] The parts that now give most trouble are the power supply and the Dallas DS1286 clock chip.[4][5]

Environment and handling

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Indigo² environmental limits (SGI product guide, 1994)
Item Specification
Power 100–120 V or 200–240 V AC
Heat dissipation 1000 BTU per hour
Operating temperature +13 to +35 °C
Storage temperature −10 to +65 °C
Relative humidity 10% to 80% operating, 10% to 95% not operating, non-condensing
Altitude 10,000 ft operating, 40,000 ft not operating

[6] The IMPACT guide gives the same temperature limits and a supply rating of 50/60 Hz at 8 A (100–120 V) or 4 A (200–240 V).[7]

SGI's handling rules for the Indigo²:[8][9]

  • Keep it out of cupboards and other small enclosed spaces, do not block the vents, and do not drape anything over it.
  • Do not run it with the front bezel or the top cover open or off, which changes the airflow.
  • Do not connect cables other than audio, or add hardware, while it is on.
  • Do not move it while it is running or within a minute of switching off, to protect the hard disk.
  • Do not plug it into an ungrounded outlet through an adapter, and do not stand it on its side without the workstation stand that came with it.

Heat matters on an old machine. CB_HK, running an Indigo² in a room at 72–74 °F (22–23 °C), measures 92–95 °F (33–35 °C) at the front and power supply fan exhausts, and another owner's machine shut itself down whenever the room went above about 80 °F (27 °C).[10]

Opening the case

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Shut down, switch off the monitor and unplug the mains lead and cables, then:[11]

  1. Open the front cover by snapping it away from the top edge of the chassis and tipping it down.
  2. Press the tabs on each side of the front bezel and pull the bezel away.
  3. Press up on the tabs on each side of the drive openings, pull up on the top cover and rotate it back and away from the chassis.

Use a wrist strap clipped to the chassis whenever boards or SIMMs are handled.[12]

The 5.25-inch drive tray

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The drive tray has to come out to reach memory bank C, the password jumper and the power supply. Disconnect the SCSI cable from the back of the tray, loosen the two captive screws below the tray at the centre front, push the tray towards the back of the system and lift it out. A drive can stay in the tray.[13][12]

Memory

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The twelve SIMM sockets are in banks A, B and C. Facing the back of the chassis, bank C is farthest from you and is filled first, then B, then A, four SIMMs at a time.[12] The sockets take 72-pin fast-page-mode SIMMs with parity, 36 bits wide, 60 or 70 ns.[14]

  1. Facing the rear, hold the SIMM with the notch in the bottom corner on your left.
  2. Tip the top of the SIMM towards you and press it into the socket at 45 degrees, then tilt it upright until the latches on both sides hug it.
  3. Check across the tops of the SIMMs that every one is fully seated.

SGI's IMPACT guide warns that the SIMMs beside the baseboard power cables come loose if the cables are knocked.[12][15]

Backplane and CPU module

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The EISA backplane (the midplane in the IMPACT guide) is the gold-coloured metal wall running from the front fan to the back of the chassis. SGI's first step for a machine with no LED is to press down firmly on the top of it, and says it is fine to press quite hard.[16][17] One owner brought two IMPACT machines back after more than 12 years in store by pressing the midplane and the CPU module firmly home; he felt both move.[18]

Power supply

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

Removing and refitting (teal Indigo²)

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SGI's procedure, with the system shut down and the cover off:[13]

  1. From the back, remove the screws holding the supply to the back and side of the chassis. The teal guide's text mentions two, but its refitting step and the IMPACT guide both give four: two on the side and two, offset, on the back.[15]
  2. Remove the 5.25-inch drive tray.
  3. Disconnect the two connectors beside the memory by pulling them straight up, and the connector by the disk drives by pulling it straight back.
  4. Push the supply about 1/4 inch towards the front, pressing on the flat surfaces round the fan, and lift it out.
  5. To fit a supply, first plug in the drive power connector, which is keyed. Lower the supply flat onto the chassis floor with the fan facing the back, as close to the drives as possible, and push it back until the metal tabs on the floor engage the slot underneath. If the chassis lifts with the supply, the tabs are engaged.
  6. Refit the four screws and the two connectors by the memory. These are not keyed, so line them up before pressing them home.

IMPACT supplies

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The IMPACT supply also feeds the midplane through a ribbon cable and a twisted-pair cable. Pinch the corrugated edges of the ribbon connector and pull the twisted-pair connector gently to release them, lift the two baseboard connectors by their straps and hang them on the hooks above the supply, then slide and lift the supply out. A new supply arrives with the midplane cables parked on a bracket on its side. In an IMPACT Ready machine the midplane cables stay attached to the supply.[15]

Preventive recap

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weblacky's advice for the Indigo² is the same as for his Indy work: buy or keep a supply that works, test it for a few days, then replace its capacitors with properly researched parts, because a supply that has already failed nearly always has a blown semiconductor as well.[19] He also warns that switching on a supply that has stood unused for years is often what damages it, and that one recapped before its first power-up often works straight away.[20] The non-IMPACT supply is awkward to open: only one end comes off, and the boards have to be unscrewed and tipped out of the case.[21] See SGI Indigo² Capacitor Replacement Guide.

Clock chip

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The DS1286 timekeeper keeps its battery inside the package and is no longer made.[5] weblacky's modification, for fitting an external replaceable cell:[5]

  1. Measure the battery voltage first. Most old chips are not completely flat; his read just over 1 V, which also confirmed the polarity.
  2. Grind into the epoxy in layers over the two battery connections, using a Dremel with a spiral cutting bit.
  3. Cut the narrow connection to the negative pole, which on his chips was on the left. Do not cut on the right: a ring of metal there forms the positive post and cutting into it opens the cell.
  4. Check with the meter that the cell is disconnected, then solder in a battery holder with the correct polarity, marking it on the chip. Reversing the cell damages the chip.

Used DS1286 chips are still sold, and Glitch Works makes a repair board for the chip's internal die; Dallas parts of that age have no freshness seal, so new old stock is as flat as used.[22]

PROM password

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From a running IRIX system, root can clear the System Maintenance password with /etc/nvram passwd_key "". Otherwise remove the jumper at the front centre edge of the CPU baseboard, under the 5.25-inch drive tray.[23]

Checklist for a machine out of storage

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  1. Open the case and look for leaking or burnt capacitors, including the tantalum capacitors on the audio board, where C57 has shorted on more than one Indigo².[21][24]
  2. Recap the power supply, or at least inspect it, before applying mains.[20]
  3. Press the backplane and the CPU module firmly home, and reseat the SIMMs and graphics boards.[16][18]
  4. Check that the front fan and the supply fan both run.[25]
  5. Watch the LED sequence and run the IDE diagnostics; see SGI Indigo² Troubleshooting Guide.
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References

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  1. ↑ Silicon Graphics, Indigo2 Workstation Owner's Guide, 007-9096-050, 1996 (File:SGI Indigo2 Workstation Owner's Guide (007-9096-050).pdf).
  2. ↑ Silicon Graphics, Indigo2 IMPACT Workstation Owner's Guide, 007-2849-004, 1996 (File:SGI Indigo2 IMPACT Workstation Owner's Guide (007-2849-004).pdf).
  3. ↑ SGI, 007-9096-050, pp. 155–160. Replaceable parts.
  4. ↑ "Indigo2 PSU woes and questions", IRIX Network forums, 23 July 2022, forums.irixnet.org. Failing Indigo² supplies.
  5. ↑ 5.0 5.1 5.2 "DIY Drilling Indigo2 RTC DS1286 Chip - Photos and Final Results", IRIX Network forums, weblacky, 17–22 July 2019, forums.irixnet.org.
  6. ↑ Silicon Graphics, Indigo2 Product Guide, INDIGO2-TM-GD (09/94), 1994, p. 8 (File:SGI Indigo2 Product Guide (INDIGO2-TM-GD-09-94).pdf). Physical environment.
  7. ↑ SGI, 007-2849-004, p. 299, Table 10-1. Physical environment specifications.
  8. ↑ SGI, 007-9096-050, p. 12. Selecting a site.
  9. ↑ SGI, 007-9096-050, pp. 207–208. Hardware do's and don'ts.
  10. ↑ "Indigo 2 powers down at high room temp.", IRIX Network forums, 9 April 2022, forums.irixnet.org. Shutdown above about 80 °F; CB_HK's exhaust temperatures.
  11. ↑ SGI, 007-9096-050, pp. 158–159. Removing the front cover, bezel and top cover.
  12. ↑ 12.0 12.1 12.2 12.3 SGI, 007-9096-050, pp. 51–53. SIMM banks and installation.
  13. ↑ 13.0 13.1 SGI, 007-9096-050, pp. 176–183. Removing the 5.25-inch drive tray and replacing the power supply.
  14. ↑ "Indigo 2", TechPubs Wiki, tech-pubs.net (retrieved 21 October 2026). SIMM type and speed.
  15. ↑ 15.0 15.1 15.2 SGI, 007-2849-004, pp. 272–282. Removing and replacing the IMPACT and IMPACT Ready power supplies; screw positions; midplane cables; caution about the SIMMs.
  16. ↑ 16.0 16.1 SGI, 007-9096-050, p. 127. Pressing the EISA backplane home.
  17. ↑ SGI, 007-2849-004, p. 227. Pressing the midplane home.
  18. ↑ 18.0 18.1 "Indigo2 power on issue", IRIX Network forums, August 2019, forums.irixnet.org. Reseating the midplane and CPU after storage.
  19. ↑ Same thread, weblacky, 23 July 2022. Recap a working supply; failed supplies have semiconductor damage.
  20. ↑ 20.0 20.1 "Two Indigo2 PSUs. Combine half of one with the other?", IRIX Network forums, weblacky, 13 November 2021, forums.irixnet.org. Powering long-stored supplies; recapping first.
  21. ↑ 21.0 21.1 "I aquired a Indigo 2 and 2 Indys - should I first recap the PSU?", IRIX Network forums, 13 August 2026, forums.irixnet.org. Inspecting before power-up; non-IMPACT supply construction.
  22. ↑ "Dallas DS1286 RTC, many on ebay?", IRIX Network forums, weblacky, 14 October 2020, forums.irixnet.org. Used chips, no freshness seal, Glitch Works repair board.
  23. ↑ SGI, 007-9096-050, pp. 150–151. Disabling the System Maintenance password.
  24. ↑ "My SGI Indigo2 audio board give off magic smoke", IRIX Network forums, 8 October 2021, forums.irixnet.org. Shorted 47 µF 20 V tantalum C57 on the audio board.
  25. ↑ SGI, 007-9096-050, p. 128. The front fan and the supply fan.


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