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SGI Visual Workstation 230 Capacitor Replacement Guide

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SGI Visual Workstation 230 system board layout (User's Guide Figure 3-1)
M23D system board layout (SGI User's Guide, Figure 3-1). PWR1, the ATX power connector, is at the left edge beside the DIMM sockets.

SGI's Silicon Graphics 230 Visual Workstation User's Guide describes the SGI Visual Workstation 230 down to replaceable parts and gives no component values. The chapters on the M23D system board were written by Acer, which designed it, and no schematic or parts list for the board or the power supply has been published.[1][2] Take every value from the part on your own board.

Where the electrolytic capacitors are

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  • The power supply, which SGI's guide treats as a sealed unit to replace whole. It is switch-selectable for 110 V or 220 V and feeds the board through the ATX connector PWR1.[3][2][4]
  • The M23D system board, around the processor socket U3 and the power connector PWR1. SGI's layout drawing shows the positions of the sockets, slots and connectors but does not identify individual capacitors.[2]

Signs of failure

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SGI's error messages do not point at capacitors directly. Look for domed tops, electrolyte on the board, and split or shrunken sleeves, and see Capacitor Failure Symptoms.

Recording your board

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  1. Remove the system board as described in SGI Visual Workstation 230 General Maintenance: side panel off, cards and cables out, loosen the single board screw, pull the board away from the I/O gasket.[5]
  2. Photograph the board square-on in sections with enough light to read the sleeves.
  3. For each electrolytic, record the printed designator, capacitance, voltage rating, temperature rating, series and can size.
  4. Note the rail each one is on by tracing it to PWR1 or to the regulator it belongs to.

Replacement

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  1. Fit parts of the same capacitance and at least the same voltage rating, in a low-ESR series where the original is one, and no larger than the original so that the processor heat sink bracket and DIMMs still fit.
  2. Observe polarity: the stripe on the sleeve marks the negative lead.
  3. Refit the board on its standoff hooks with the retaining bracket, tighten the screw, and reconnect every cable before the first power-up.[5]
  4. Check the BIOS Setup values afterwards; take the opportunity to replace the lithium battery at BT1 if the settings were not being kept.[6]

Warning: the power supply can hold dangerous voltages after it is unplugged; SGI's guide says so explicitly.[4] Leave it unplugged until its input capacitors have discharged and confirm with a meter before touching the primary side.

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References

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  1. ↑ Silicon Graphics, Inc., Silicon Graphics 230 Visual Workstation User's Guide, 007-4263-001, March 2000, front matter (File:SGI Visual Workstation 230 User's Guide (007-4263-001).pdf). Chapters 3 and 4 provided by Acer Incorporated.
  2. ↑ 2.0 2.1 2.2 SGI, 007-4263-001, pp. 57-62, Figure 3-1 and Table 3-1. Board layout and connectors.
  3. ↑ SGI, 007-4263-001, pp. 6-7. Power supply, voltage switch.
  4. ↑ 4.0 4.1 SGI, 007-4263-001, p. 29. The power supply may contain dangerous voltages when unplugged; no user-serviceable parts.
  5. ↑ 5.0 5.1 SGI, 007-4263-001, pp. 43-47. Removing and refitting the system board.
  6. ↑ SGI, 007-4263-001, pp. 72-75. CMOS battery and Setup messages.


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