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SGI Onyx 300 Capacitor Replacement Guide

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SGI Onyx 300 rack (User's Guide Figure 1-1)
Onyx 300 rack: the InfiniteReality graphics module, with its own mains supply, above the power bay at the bottom (SGI User's Guide, Figure 1-1)

Capacitor notes for the SGI Onyx 300. SGI's user's guide gives no component lists or capacitor values for any module, and no owner has published a capacitor list for the Onyx 300 graphics module, its compute modules or its power bay. The values in your system have to be read from the parts themselves; do not fit values copied from another machine.

The compute module's supply and boards are covered on SGI Origin 300 Capacitor Replacement Guide, with SGI's figures for the supply and the monitored rails. The notes below cover the graphics module, the power bay and the L2 controller supply.

Warning: the graphics module supply, the compute module supplies, the power bay supplies and the L2 controller's supply all run from the mains, and their input capacitors can hold a dangerous charge after the cord is pulled. Unplug the module, wait, and confirm with a meter that the input capacitors have discharged before working inside a supply.

Where the power is converted

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Power supplies in an Onyx 300 system (SGI User's Guide)
Assembly What SGI documents
InfiniteReality graphics module Its own supply, on the front side of the midplane, fed from a 220 V outlet outside the rack; 180–254 V AC, about 2000 W.
Compute module 110/220 V AC, autosensing, about 275 W, from the PDU.
Power bay (systems with PCI expansion modules, and early systems with a DC-powered NUMAlink module) Up to six positions, of which the Onyx 300 uses two or three; 48 V and 12 V standby outputs, 1840 W and 90 W with N+1 redundancy. Each supply is 123.5 × 69.5 × 347.3 mm and weighs 3.38 kg.
L2 controller supply (systems with an AC-powered NUMAlink module) A small supply on the side of the rack that turns AC from the PDU into the 48 V the L2 needs.

[1][2]

What owners have found

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No owner reports of failed capacitors in Onyx 300 graphics module supplies or power bay supplies have been found. Owners' reports on the related compute modules are on SGI Origin 300 Capacitor Replacement Guide, and on the later SGI Origin 350 Capacitor Replacement Guide.

Recording your own system

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  1. Shut IRIX down, power the system off at the L2 with pwr d, turn off the graphics module's rear switch and unplug every cord. The compute modules have no power switch; unplug them from the PDU.[3]
  2. Photograph both sides of each board or supply before desoldering anything, with designators readable.
  3. For each electrolytic or polymer capacitor, write down the designator, capacitance, voltage rating, temperature rating, maker and series, size and polarity.
  4. Look for domed tops, leakage at the base, brown or crystalline residue and corroded traces near capacitors.
  5. Measure ESR with the part out of circuit and compare it with the maker's figure for that series.
Record sheet
Assembly Designator Capacitance Voltage Temperature Series Size Condition
Graphics module supply
Power bay supply
L2 controller supply
Compute module supply

Replacing

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  • Fit the same capacitance and at least the same voltage rating, with 105 °C parts, and low-ESR series wherever the original was a low-ESR type.
  • Replace solid polymer parts with the same technology at an equal or lower ESR.
  • Keep the original size where a heat sink or neighbouring part leaves no room for a larger one.
  • Mark polarity on your photographs before removing anything.

After the repair

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  1. Reconnect the module, start its L1 (rear switch on, or PDU breaker on for a compute module) and check that its display reads L1 running.[3]
  2. Power it up from the L2 and run env on it. Every voltage should be inside its warning limits; SGI counts 10% from nominal as a warning and 20% as a fault.[4][5]
  3. Measure the rails you worked on with a meter as well.
  4. For a power bay supply, check that its green LED is lit.[4]
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References

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  1. ↑ Silicon Graphics, SGI Onyx 300 Graphics System User's Guide, 007-4509-002, May 2002, chapter 1, pp. 2–3, 19 and 55–56 (File:SGI Onyx 300 Graphics System User's Guide (007-4509-002).pdf). Graphics module power supply, power bay, L2 controller supply, May 2002 change.
  2. ↑ SGI, 007-4509-002, appendix A, pp. 128–134, Tables A-3, A-5, A-9 and A-10. Graphics module, compute module and power bay specifications.
  3. ↑ 3.0 3.1 SGI, 007-4509-002, chapter 2, pp. 82–97. Power connections, powering on and off.
  4. ↑ 4.0 4.1 SGI, 007-4509-002, chapter 4, pp. 118–120, Tables 4-1 and 4-2. Power supply LED, voltage thresholds.
  5. ↑ Silicon Graphics, SGI L1 and L2 Controller Software User's Guide, 007-3938-006, chapter 3, pp. 66–68 (File:SGI L1 and L2 Controller Software User's Guide (007-3938-006).pdf). env command.


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