SGI Power Series General Maintenance

An SGI Crimson in the Power Series single-tower chassis, with the I/O door open (Patrick Finnegan, CC BY 2.0)

Care and board-level service for the SGI Power Series (4D/120 to 4D/480). No SGI owner's guide or service manual for the range is available online, so these procedures come from A. J. Corda's This Old SGI FAQ, Gerhard Lenerz's sgistuff.net and jan-jaap's restoration of a 4D/380 rack, with SGI's 1990 brochure for the site requirements. The single-tower chassis and backplane are shared with the SGI Crimson, so the chassis notes on SGI Crimson General Maintenance also apply to single-tower machines, but the Crimson's boards and slot use differ.

Site and power

Power Series site requirements (SGI brochure, 1990)

Item	Specification
Mains	115 V nominal (87–132 V), 47–63 Hz; 220 V models available
Outlet	NEMA 5-20 (20 A)
Chassis load	1840 VA, 1310 W, 4470 BTU/hr
Operating environment	10–35 °C (50–95 °F), 10–80% relative humidity, non-condensing
Storage	−40 to 60 °C, 10–90% relative humidity, non-condensing

• This Old SGI warns that a Power Series machine needs a 20 A circuit, that a 15 A outlet with an adapter may not cope depending on the boards and disks fitted, and that the machine's own 16 A breaker gives little protection on a 15 A outlet. Corda recommends having an electrician fit a proper 20 A outlet for a machine that will run for long periods.
• The deskside chassis weigh 82 kg (single tower) to 84–86 kg (twin tower), and jan-jaap's 4D/380 rack stands 1.6 to 1.7 m tall. Move them with several people.

Safety before opening

• The power supplies are high-current units, usually rated above 1000 W; Corda describes the 5 V, 200 A output of the LH Research supply in the Professional IRIS as screwdriver-melting.
• In the Power-One SPM5 supplies, most of the input side is not isolated from the mains, the bias supply runs whenever the supply is connected, even with the system switched off, and about 70 V stays on the main filter capacitors for more than ten minutes after the fan has run down. Unplug the system, wait, and measure before touching anything.

Backplane connectors

jan-jaap found that the boards in his machines had become so hard to insert and remove that he feared snapping the handles, and that a bent backplane pin could be crushed without his noticing. His remedy:

1. Take the backplane out of the chassis.
2. Brush the pure DeoxIT Gold liquid onto the male side of each backplane and board connector. He does not use the spray, and avoids contact sprays in general because he finds they attract dirt.
3. Treat the memory SIMM contacts the same way.

Check every connector for bent pins while the backplane is out.

Slot rules

CPU and memory boards

• In the deskside chassis, CPU boards go in slots 6 and 7, filled from slot 6; in the POWERCENTER and graphics racks they go in slots 8 to 11, and in the SKYWRITER rack in slots 12 and 13.
• Put the fastest CPU board in the first CPU slot, so that IRIX boots on the fastest processor.
• All CPU boards should carry the same boot PROM version, and the PROMs on the I/O board must match the CPU PROMs.
• Valid processor counts are 1, 2, 4, 6 and 8. A single-processor board should not be mixed with dual-processor boards; sgistuff.net says such a mix is unsupported but may still work, and that boards of different speeds have been run together.
• The single tower has one memory slot, slot 8. The twin tower has two, slots 8 and 9, filled from slot 8.

VME slots

• Fill the VME slots from slot 1 upwards with no gaps.
• Remove the bus grant (BG) and interrupt acknowledge (IACK) jumpers for each VME slot that holds a board, and leave them fitted for empty slots. They are on the back of the backplane, between the upper connectors of slots 1 to 3, so the back panel has to come off to reach them.
• A genlock board (CG2 or CG3) always goes in slot 4, with the four genlock jumpers fitted on the backplane to the left of the slot 4 lower connector.
• jan-jaap finds the Power Series less critical about VME jumpers than the Professional IRIS, though some setups still need jumpers removed.

IO3B board

The IO3B serves both the Power Series and the Crimson. For a Power Series CPU board, the jumper at position C0F0 must be on the middle pins; for a Crimson it goes on the pins nearest the backplane connector.

Memory

MC2 board

• The MC2 takes SGI's proprietary 80-pin SIMMs of 2 MB or 8 MB. Fit them in groups of four, starting at the edge of the board nearest the status LEDs.
• sgistuff.net gives 16 MB (eight 2 MB SIMMs) as the minimum and 256 MB (thirty-two 8 MB SIMMs) as the maximum, and the whole system may not exceed 256 MB even when a second MC2 would fit.
• Officially one MC2 holds only one SIMM size. sgistuff.net reports some boards running with mixed sizes, and jan-jaap recalls that mixing works if each group of four is identical.
• Old MC2 revisions do not take 8 MB SIMMs; sgistuff.net names board 030-0117-001 as one of them.
• On a working MC2 the four red LEDs go out after the power-on tests, and the eight green LEDs show which SIMM groups are fitted and accessible.

IP9 on-board memory

The IP9 board of the 4D/210 has 16 SIMM sockets for 2 MB SIMMs, filled in groups of four starting at the end nearest the serial connector. If an MC2 is also fitted, it must be full before the system will use the IP9's sockets, and the total may not exceed 256 MB.

SCSI in the single tower

sgistuff.net describes two ways of cabling the two SCSI channels of an IO3 or IO3B in the single tower:

• Jumpered: the two connectors under the drive bays are bridged with a short SCSI cable and the internal cable from the card cage is left unconnected. All four internal drives are then on channel 0, and channel 1 is free for external devices.
• Terminated: both connectors under the drive bays are terminated and the internal cable is connected to the I/O board. Channel 0 then serves the lower bays and channel 1 the upper bays, two internal devices each, and either channel can be extended externally instead of being terminated.

Clock and NVRAM

This Old SGI says the IO2 and IO3 boards use the same kind of SmartWatch module as the Professional IRIS: a socket containing a clock chip and a lithium cell, with the NVRAM chip plugged into it. When the cell runs out, the clock misbehaves and the PROM environment variables can be lost at power-off. Before the battery fails, record the PROM settings with the printenv command at the PROM monitor and keep a paper copy.

Cooling

• The system switches off if its thermal sensor, in the top of the main tower, reaches 140 °F (60 °C). Once it has cooled, press the reset switch through the small hole: on the twin tower it is on the front of the drive tower, to the right of the lower drive bay; on the single tower it is on the control panel at the top right of the front, below the midpoint between the two status LEDs.
• jan-jaap's rack draws air in through the grille under the card cage and blows it out of the top, so keep the grille clear and leave space above the rack.
• sgistuff.net refers to the Crimson page for the cooling and power changes needed when RealityEngine was fitted to a deskside machine; see SGI Crimson General Maintenance#Fans and cooling.

Checklist for a machine out of storage

1. Do not apply mains to an untested supply. Inspect it, and rebuild it if the capacitors have leaked; see SGI Power Series Capacitor Replacement Guide.
2. Inspect the tantalum capacitors on the I/O bulkhead and boards. jan-jaap replaced the electrolytic capacitors on his CPU and I/O boards before first power-up, after a bulkhead tantalum capacitor burst into flames.
3. Clean the backplane and board connectors and check for bent pins.
4. Check the slot rules, PROM versions and jumpers above.
5. Bring the machine up in a minimal configuration first; see SGI Power Series Troubleshooting Guide.

Related pages

• SGI Power Series
• SGI Power Series Troubleshooting Guide
• SGI Power Series Capacitor Replacement Guide
• SGI Crimson General Maintenance
• Recommended Tools