Jump to content

SGI Origin 300 Capacitor Replacement Guide

From RetroTechCollection
SGI Origin 300 internal components
Origin 300 internal layout: the power supply sits at the right-hand side, beside the IP45 motherboard, DIMMs, fans and I/O-8 assembly (SGI NUMAlink Module User's Guide, Figure A-6)

Capacitor notes for the SGI Origin 300. SGI's user's guides name only PCI cards, disk drives and memory as customer-replaceable units, and refer everything else, the power supply and motherboard included, to an SGI system support engineer.[1] They give no component lists, and no owner has published a capacitor list for the Origin 300 supply or boards, so the values in your server have to be read from the parts themselves.

Warning: the supply runs from mains and its input capacitors hold a dangerous charge after the cord is pulled. Unplug the server, let the supply stand, and confirm with a meter that the input capacitors have discharged before touching anything inside it.

What SGI documents

[edit | edit source]

The power supply is a non-redundant modified WTX unit with autosensing 110/220 V input and a maximum output of 460 W at 3.3, 5 and 12 V. A cable harness with several connectors carries its output to the server. Two fans inside it cool it in an N+1 arrangement.[2] SGI gives the server's maximum draw as 275 W.[3] The IP45 motherboard carries five voltage regulator modules (VRMs) that make the lower voltages its components need.[2]

The L1 controller measures each rail and compares it with fixed limits. The env output SGI prints for a working server shows these:[4]

Origin 300 monitored rails (SGI NUMAlink Module User's Guide, Example C-12)
Rail Warning limits (10%) Fault limits (20%) Reading on SGI's example
12V IO 10.80 to 13.20 V 9.60 to 14.40 V 12.31 V
12V DIG 10.80 to 13.20 V 9.60 to 14.40 V 12.12 V
5V 4.50 to 5.50 V 4.00 to 6.00 V 4.99 V
3.3V 2.97 to 3.63 V 2.64 to 3.96 V 3.34 V
5V aux 4.50 to 5.50 V 4.00 to 6.00 V 4.99 V
3.3V aux 2.97 to 3.63 V 2.64 to 3.96 V 3.41 V
2.5V 2.25 to 2.75 V 2.00 to 3.00 V 2.50 V
CPU core (Speedo2 CPU) 1.35 to 1.65 V 1.20 to 1.80 V 1.49 V
1.5V 1.35 to 1.65 V 1.20 to 1.80 V 1.48 V

A rail past its fault limit starts a 30-second power-off.[5]

Signs that point to the supply or a regulator

[edit | edit source]
  • The L1 display or log shows ATTN: x.xV high (or low) warning limit reached or fault limit reached for one rail.[5]
  • Auto power down in xx seconds soon after power up.[5]
  • The L1 controller does not run at all with the cord connected and the PDU breaker on. The base module has no power switch, so its L1 should run whenever it has mains power; SGI's chart stops at checking the power connection.[6][5]
  • A low reading on one rail is not always a failed supply. In one owner's server the L1 reported the 5V aux rail at 3.22 V and 3.3V aux at 1.7 V, values the server could not have run with, and a replacement supply, VRMs and I/O-8 assembly changed nothing. Forum members suspected the Dallas DS1780 monitoring chips.[7] Measure the rail with a meter before taking the supply apart.

See also SGI Origin 300 Troubleshooting Guide and Capacitor Failure Symptoms.

[edit | edit source]

On the related SGI Origin 350, an owner traced a missing PCI 5V rail to a switching regulator on the interface board; a board repairer on the forum pointed out that SGI used the same regulator design on many late boards, with solid aluminium or polymer output capacitors, and suggested checking their ESR. New output capacitors did not cure that fault, and a new regulator chip did.[8] The SGI Origin 2000 supply, an older and different design, has had leaking electrolytics; see SGI Origin 2000 Capacitor Replacement Guide.[9]

Recording your own server

[edit | edit source]
  1. Shut IRIX down with init 0, power the server down with the L1 command power down, and unplug the cord. The base module has no power switch, and its L1 controller stays live while the cord is connected.[10][6]
  2. Photograph both sides of every board before desoldering anything, with designators readable.
  3. For each electrolytic, write down the designator, capacitance, voltage rating, temperature rating, maker and series, can diameter and height, lead spacing and polarity.
  4. Look for domed tops, leakage at the base, brown or crystalline residue on the board, 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.
  6. Do the same for the motherboard regulator sections, the VRMs, the I/O-8 assembly and the SCSI backplane.
Record sheet
Board Designator Capacitance Voltage Temperature Series Size (D × H) Condition
Power supply, primary
Power supply, secondary
IP45 motherboard
VRM

Replacing

[edit | edit source]
  • Fit the same capacitance and at least the same voltage rating, 105 °C parts, and low-ESR series wherever the original was a low-ESR type.
  • Replace solid polymer or solid aluminium parts with the same technology, at an equal or lower ESR.
  • Keep the original can size where the board or a heat sink leaves no room for a larger one.
  • Observe polarity; mark the negative stripe on your photographs before removal.
  • Clean off any electrolyte with isopropyl alcohol and inspect nearby traces under magnification.

After the repair

[edit | edit source]
  1. Reconnect the supply harness and all cables and plug in the cord. The L1 display should show L1 running.[10]
  2. At the L1 prompt run power up, then env. Every rail should read inside its warning limits in the table above, and every fan should run above its 2160 rpm warning threshold.[4]
  3. Check log for new warnings, and clear old ones with env reset.[4]
  4. Measure the rails you worked on with a meter as well, to confirm that the L1 is reading them correctly.
[edit | edit source]

References

[edit | edit source]
  1. ↑ SGI, 007-4365-002, chapter 4, pp. 43-44, and About This Guide. Customer-replaceable units; other parts to be fitted by an SGI system support engineer.
  2. ↑ 2.0 2.1 Silicon Graphics, SGI Origin 300 User's Guide, 007-4365-002, April 2002, chapter 1, pp. 10-13 (File:SGI Origin 300 User's Guide (007-4365-002).pdf). IP45 motherboard, VRMs, power supply, cooling.
  3. ↑ SGI, 007-4365-002, appendix A, p. 65, Table A-2. Power requirements.
  4. ↑ 4.0 4.1 4.2 SGI, 007-4498-002, appendix C, pp. 184-185, Example C-12, and pp. 177-205. env output with warning and fault limits; L1 command set.
  5. ↑ 5.0 5.1 5.2 5.3 Silicon Graphics, SGI Origin 300 System with NUMAlink Module User's Guide, 007-4498-002, 2002, chapter 5, pp. 106-109, Tables 5-1 and 5-2 (File:SGI Origin 300 System with NUMAlink Module User's Guide (007-4498-002).pdf). Troubleshooting chart and L1 messages.
  6. ↑ 6.0 6.1 SGI, 007-4498-002, chapter 3, p. 81. The Origin 300 base module has no power switch; its L1 controller is on whenever the PDU circuit breaker is on.
  7. ↑ "Origin 300 is not starting", IRIX Network forum, posts by blacksmith, weblacky and jan-jaap, 31 March to 11 April 2022, forums.irixnet.org/thread-3466.html. Low auxiliary rail readings, parts swapped, DS1780 suspected.
  8. ↑ "Origin 350 - PCI 5V missing", IRIX Network forum, posts by aSpartan111 and weblacky, September to December 2023, forums.irixnet.org/thread-4064.html. LTC1629 regulator repair on the Origin 350 interface board; output capacitor ESR.
  9. ↑ Pentium, "Onyx2/Origin 2000 Power Supplies and Capacitors - It's time, folks", IRIX Network forum, 27 December 2024, forums.irixnet.org/thread-4427.html. Leaking capacitors in the Origin 2000 supply.
  10. ↑ 10.0 10.1 SGI, 007-4365-002, chapter 3, pp. 35-37. L1 display, powering on and off.


Retrieved from "https://retrotechwiki.com/index.php?title=SGI_Origin_300_Capacitor_Replacement_Guide&oldid=29418"