SGI Power Indigo² General Maintenance

Removing the R8000 CPU module: the five screws, raising the module, the module upright on its flex cable, releasing the connector tabs, and lifting it away (SGI, 108-0139-001 Figure 1-8)

Routine service for the SGI Power Indigo², from Silicon Graphics' POWER Indigo2 and POWER CHALLENGE M Upgrade Instructions (108-0130-001, 1994) and its hardware note 64 MB SIMM Upgrade for R8000 Indigo2 and POWER CHALLENGE M Systems (108-0139-001, 1995). The POWER Indigo² is a teal Indigo² with the IP26 system board and R8000 CPU module, so the case, front bezel, environment limits, power supply removal, clock chip and PROM password are as described on SGI Indigo² General Maintenance. The procedures below are the ones the R8000 module changes.

Before you start

SGI's upgrade instructions single out the R8000 for static precautions: because of the design of the R8000, proper ESD measures must be used.

• Wear a wrist strap clipped to the chassis whenever the cover is off.
• Take a board out of its antistatic bag only when you are grounded and working on it.
• Do not use an ohmmeter on the R8000 CPU module.
• Do not set the module down roughly on a hard surface, and do not scrape its underside against the chassis. Several capacitors on the back of the module help control its internal clocks, and if any one of them is damaged the module will not work.

Tools SGI lists for work on the R8000 machines: a #2 Phillips screwdriver, the plastic SIMM removal tool and a wrist strap, with a 6 mm hex nut driver and a flat-bladed screwdriver as optional extras.

Drive tray

The 5.25-inch drive tray sits above the SIMM banks and has to come out before the memory or the R8000 module can be reached.

1. Unlatch and disconnect the flat flex SCSI cable from the rear of the tray.
2. Undo the captive screws at the lower front of the tray.
3. Slide the tray back to unlatch it, then lift it up and out.

When refitting, keep the tray level as you lower it so that a corner does not strike the R8000 module. The back of the module is very close to the underside of the tray: before sliding the tray forward and locking it, look through the perforated floor of the tray to check the clearance.

R8000 CPU module

The module has to come out to fill SIMM bank C. One owner also found that the module overhangs one of the power supply connectors, so it has to be unscrewed and lifted out every time the supply is plugged in or unplugged.

Removing the module

SGI's procedure:

1. Remove the 5.25-inch drive tray.
2. With the wrist strap connected, remove the five screws that hold the module to its standoffs, using a #2 Phillips screwdriver.
3. Use both hands to raise the module off the standoffs and into a vertical position. This puts the least stress on the flex cable.
4. Hold the module steady with one hand, and with the other lift the tabs at each end of the flex-cable connector and remove the connector. Do not twist or rock the module on the flex cable; bending and twisting can damage it.
5. Lift the module away and lay it on an antistatic surface.

Refitting the module

SGI's procedure:

1. Hold the module in one hand and seat the flex-cable connector on the IP26 board with the other, pressing firmly and evenly with your fingers. Do not put too much weight on the flex cable, and do not twist or rock the module on it.
2. Keep the module clear of the 3.5-inch drive bay; the critical capacitors on its back are easily knocked.
3. With the connector seated, move your hands to the front and back edges of the module and lower it onto the standoffs.
4. Lay the insulating sheet along the rear edge of the module, aligned with the two rear-most screw holes.
5. Fit the five screws: four 8 mm M3 screws and one 30 mm M3 screw, which goes in the position marked on SGI's drawing for this step. Tighten them with your fingers first, then snug them with the screwdriver.

SGI's drawing of the module shows the +3.3 V and +5 V supplies entering through two of the standoffs, so every screw belongs back in place.

Memory

SIMM banks on the IP26 board. SIMMs in bank C and the last socket of bank B must be under about 32 mm tall (SGI, 108-0130-001 Figure 2-1)

Rules

• The twelve sockets form banks A, B and C. Every SIMM in a bank must be the same size.
• 64 MB SIMMs may fill only two of the three banks; the third must hold 32 MB or smaller SIMMs. That gives SGI's maximum of 640 MB.
• SIMMs in bank C and in the last socket of bank B must be no taller than about 32 mm, or they can damage the R8000 module. The 1994 instructions give 1.27 in and sockets S7 to S12; the 1995 note gives 1.260 in and sockets S8 to S12.
• SGI recommended filling bank C first when the IP26 board was fitted, because the module makes that bank hard to reach afterwards. Its 1995 note puts 64 MB SIMMs in banks A and B and smaller SIMMs in bank C.
• The sockets take 72-pin fast-page-mode SIMMs with parity, 36 bits wide, at 60 or 70 ns.

Removing SIMMs

SGI's method, with the power off and the wrist strap clipped to the chassis:

1. Work from the rear of the system. SGI says to take SIMMs out in order from the rear-most socket (the lowest number) towards the front; a SIMM cannot be fitted while there is another directly behind it.
2. Use the plastic removal tool to push the metal retaining clip at one end of the socket outwards. On standard SIMMs, press straight down on the release latch. On wider SIMMs, such as the 64 MB modules, which extend over the latches, push outwards on the front part of the latch.
3. Do the same at the other end. The SIMM tilts back towards the rear of the system.
4. Lift it out of the socket.

Fitting SIMMs

1. Hold the SIMM by its edges with the notched end on your left, facing the back of the system.
2. Tilt it about 40 degrees back towards you, set it in the socket, then push it forward and down until both ends click into place. The plastic pins on the socket must go through the small holes at each end of the SIMM.
3. Check that its top is level with the SIMMs beside it and that it is not sitting at an angle.

SGI warns that the 64 MB SIMMs tend to scrape the right-hand retaining clip of the socket behind, and that a DRAM pin can snag on the left-hand clip. If a SIMM snags, hold the clip back with the removal tool while you position it.

After any memory change, check the total with hinv at the Command Monitor; see the troubleshooting guide.

Power supply

The supply comes out as on the teal Indigo²; see SGI Indigo² General Maintenance#Power supply. SGI's steps in the R8000 upgrade instructions are: remove the four screws (two on the back of the system, two on the side), disconnect the supply cables, slide the supply about 6 mm (1/4 in) forward and lift it out. On a POWER Indigo², lift the R8000 module out first if it covers the supply connector.

• A replacement supply must be revision S or later. The revision is marked on the side of the supply. Revision S gives a nominal 3.45 V on the 3.3 V rail, which the R8000 needs.
• On some older Indigo² chassis a new supply will not slide into place. SGI's fix is to take it out and bend the two tabs on its underside outwards by about 2 to 3 mm, so that they engage the U-shaped slots in the chassis floor.
• For recapping, see SGI Power Indigo² Capacitor Replacement Guide.

Checklist for a machine out of storage

1. Check the label on the side of the power supply for revision S or later.
2. Inspect or recap the supply before applying mains; see SGI Indigo² Capacitor Replacement Guide.
3. Check the tantalum capacitors on the audio board, C57 in particular, for shorts. That capacitor has failed on more than one Indigo², including an R8000 machine.
4. Look over the back of the R8000 module for knocked or broken capacitors without scraping it on the chassis.
5. Check the SIMM heights in bank C and the last socket of bank B.
6. Power on and check hinv -v at the Command Monitor against SGI's expected output.

Related pages

• SGI Power Indigo²
• SGI Power Indigo² Troubleshooting Guide
• SGI Power Indigo² Capacitor Replacement Guide
• SGI Indigo² General Maintenance
• SGI Challenge M
• Recommended Tools