Jump to content

SGI Onyx 4 Capacitor Replacement Guide

From RetroTechCollection
SGI Onyx4 G2N-brick internal view (User's Guide Figure 1-3)
Inside a G2N-brick: the power supply sits in its bay at the front right, beside the node board and the graphics boards on their riser (SGI User's Guide, Figure 1-3)

Capacitor notes for the SGI Onyx 4 graphics bricks. SGI's user's guide treats the brick's power supply as a sealed replaceable unit and gives no component lists or capacitor values for it, for the boards or for the graphics cards.[1] No owner has published a capacitor list for an Onyx4 brick either. The values in your brick have to be read from the parts themselves; do not fit values copied from another machine.

The host compute modules are those of the SGI Origin 350; their supplies and regulators are covered on SGI Origin 350 Capacitor Replacement Guide and SGI Onyx 350 Capacitor Replacement Guide.

Warning: each brick's supply runs from the mains, and its input capacitors can hold a dangerous charge after the cord is pulled. Unplug the brick, wait, and confirm with a meter that the input capacitors have discharged before working inside the supply.

Where the power is converted

[edit | edit source]
Power conversion in an Onyx4 graphics brick
Assembly What is documented
Power supply One sled-mounted supply per brick, at the front right, with its own fan. Input 90–132 or 180–264 V AC, 50–60 Hz, inrush current 20 A. SGI does not name its maker or give its output rails.
Brick load G2-brick 150 W maximum, G2N-brick 350 W maximum.
G2N-brick node and interface boards kaigan's hinv lists the same four-processor node board and 2U interface board (2U_INT_53) in his G2N-brick as in his Origin 350-type base compute module.
Graphics boards Two ATI cards on an AGP riser, identified by kaigan as FireGL X1.

[1][2][3]

What owners have found

[edit | edit source]

No owner reports of failed capacitors in an Onyx4 brick supply or on its graphics boards have been found. The reports that bear on the G2N-brick concern its compute boards:

  • aSpartan111 traced a missing PCI 5V rail on an Origin 350 2U interface board to an LTC1629 switching regulator. New 220 µF 6.3 V output capacitors on that regulator did not cure it; a new LTC1629 did.[4]
  • weblacky describes the regulator output capacitors of this generation as solid polymer types, and suspects ageing of their ESR in rails that drift low; he had not confirmed it.[5]

See SGI Origin 350 Capacitor Replacement Guide for these reports in full.

Recording your own brick

[edit | edit source]
  1. Shut IRIX down, power the system off, and unplug the brick's power cord.[6][1]
  2. Take the supply out from the front, or open the brick, as described on SGI Onyx 4 General Maintenance. Let the components cool for about five minutes first; SGI warns that they may be hot.[1]
  3. Photograph both sides of every board or supply before desoldering anything, with designators readable.
  4. For each electrolytic or polymer capacitor, write down the designator, capacitance, voltage rating, temperature rating, maker and series, size and polarity.
  5. Look for domed tops, leakage at the base, brown or crystalline residue and corroded traces near capacitors.
  6. 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
Brick power supply
AGP riser
Graphics board, pipe 0
Graphics board, pipe 1
2U interface board (G2N-brick)
Node board (G2N-brick)

Replacing

[edit | edit source]
  • 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, duct or neighbouring part leaves no room for a larger one.
  • Mark polarity on your photographs before removing anything.

After the repair

[edit | edit source]
  1. Refit the supply with its handle open, press the handle down to lock it, and close the screen cover without pinching the fan's ribbon cable.[1]
  2. Plug the brick in: the supply LED should blink green until the main DC output comes on, then show steady green. Amber means a voltage, temperature or current limit has been exceeded.[1]
  3. Power the system up and read env on the brick's L1. SGI counts 10% from nominal as a warning and 20% as a fault.[1]
  4. Run hinv and check that the brick still shows two graphics boards.[6]
[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 SGI, 007-4634-002, appendix A, pp. 83–96. L1 voltage thresholds, safety, power supply LED and replacement.
  2. ↑ SGI, 007-4634-002, appendix B, p. 120, Table B-2. Specifications.
  3. ↑ kaigan, "It Lives! SGI Onyx350 Prototype/Onyx4 - "Artemis"", IRIX Network forum, July 2020 to June 2021, forums.irixnet.org. hinv listings, FireGL X1 boards on an AGP riser.
  4. ↑ aSpartan111, robespierre, jwhat, weblacky and jan-jaap, "Origin 350 - PCI 5V missing", IRIX Network forum, September to December 2023, forums.irixnet.org.
  5. ↑ weblacky, replies of November 2020 to March 2022 in "O350 Voltage Fault:ATTN: 1.8V low fault limit reached @ 1.396V.", IRIX Network forum, forums.irixnet.org.
  6. ↑ 6.0 6.1 Silicon Graphics, Silicon Graphics Onyx4 UltimateVision User's Guide, 007-4634-002, June 2004, chapter 2, pp. 28–33 (File:SGI Onyx4 UltimateVision User's Guide (007-4634-002).pdf). Power, booting, verifying connections.


Retrieved from "https://retrotechwiki.com/index.php?title=SGI_Onyx_4_Capacitor_Replacement_Guide&oldid=29652"