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IBM PS/ValuePoint Capacitor Replacement Guide

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IBM PS-ValuePoint 486SX motherboard
PS/ValuePoint 486SX system board with eight 30-pin SIMM sockets, the layout of the 1992 6384 425SX. (Image: Wikimedia Commons, CC BY-SA 3.0)

IBM serviced the IBM PS/ValuePoint (machine types 6381, 6382, 6384 and 6387, and the 64xx types added in its 1996 manual) at field-replaceable-unit (FRU) level. Its Hardware Maintenance Manual gives part numbers for the system board and power supply and no component values or schematics.[1] The one capacitor fault documented for the family is on the Alps diskette drive, not the system board.

Safety

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The power supply runs from the mains and its primary reservoir capacitor can hold a dangerous charge after the machine is unplugged. Unplug the power cord, open the supply only on the bench, and measure across the reservoir capacitor before touching anything on the primary side. IBM's safety inspection guide lists a bulging capacitor among the hazards to look for.[2]

What IBM documents

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The 1993 manual mentions capacitors twice: the "bulging capacitor" in the safety inspection guide, and C17 on the 1992 6384 425SX, 433DX and 466DX2 system boards. C17 is not a fault point. IBM's procedure for removing a forgotten power-on password on those boards is to move JP8 to pins 2 and 3, short C17 momentarily, and return JP8 to pins 1 and 2.[3] The board layouts label it "Capacitor (Used with JP8 to erase password.)".[4]

No published capacitor list exists for any PS/ValuePoint system board or power supply. Photograph the board, read each value and voltage off the part, and replace like for like with an equal or higher voltage rating.

Diskette drive capacitor

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The zxnet collection page for the 425SX/Si (type 6381-Fxx) reports that the Alps diskette drive has a surface-mount aluminium electrolytic capacitor next to the power connector which may be leaking, and the drive in the collection's own machine has a leaking capacitor.[5] The report names one capacitor and gives no value.

  1. Remove the diskette drive and its logic board.
  2. Read the value and voltage off the capacitor beside the power connector.
  3. Remove it with hot air or two irons, lifting it straight off the pads.
  4. Clean any electrolyte from the pads and nearby tracks with isopropyl alcohol and check the tracks for corrosion.
  5. Fit a part of the same capacitance and an equal or higher voltage rating, observing the polarity marking.

See Floppy Drive Repair for general drive servicing.

Clock battery

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The system board battery is a lithium cell, FRU 33F8354 (CR2032), in a holder at B1 or BT1; the 6384 P60/D uses a different battery, FRU 71G6630.[6] The same zxnet page reports a leaked CR2032 from one of its machines, with little damage done.[5] If a cell has leaked, clean the holder and the board around it and check nearby tracks before fitting a new cell. See Battery Explosion, Capacitor or Corrosion Damage.

Power supplies

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The supply is a single FRU. IBM fitted three ratings to the 63xx types and a 250 W supply to the 64xx towers:

PS/ValuePoint power supplies
Rating Machine types FRU
100 W 6381, 6382 92F0415
145 W 6384 (1992 models: 325T, 425SX, 433DX, 466DX2) 52G8741
200 W 6384 /D, 6387 /T 92F0411
100 W 6472 92F0415
200 W 6482, 6484 92F0411
250 W 6492, 6494 82G5874

FRU numbers are from the 1996 manual's parts lists; the 1993 edition assigns the 100 W supply to the 6382 /S only and lists the 6381 against the 200 W supply, which the 1996 edition and IBM's product reference correct. The product reference gives 200 W for the 6384 P60/D.[7][8] The product reference describes the 63xx supplies as universal with a manual voltage switch; IBM's support notes for the 6384 say the switch is preset to 230 V and must be moved to 115 V on 115 V mains.[8][9]

Checking the supply after work

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IBM's check is made at the system board connector with the supply cables connected to the board. If a voltage is out of range and the power cord is good, IBM replaces the supply.[10]

System board power connector limits (IBM)
Output Range
+5 V +4.75 to +5.25 V
−5 V −4.5 to −5.5 V
+12 V +11.4 to +12.6 V
−12 V −10.8 to −13.2 V
Power Good +4.75 to +5.25 V

The drive connector carries +5 V and +12 V; IBM's hard disk drive specifications allow ±5 % on +5 V and ±8 % on +12 V.[11]

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References

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  1. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, p. v and parts lists pp. 18-26. PDF.
  2. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, p. 29 (Safety Inspection Guide).
  3. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, pp. 44-45 (Power-On Password).
  4. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, pp. 86-89 (6384 425SX, 433DX and 466DX2 system board layouts).
  5. ↑ 5.0 5.1 "IBM PS/ValuePoint 425SX/Si (Type 6381-Fxx)", zxnet (zx.net.nz), last modified 8 June 2024. Retrieved 2026-09-30.
  6. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, p. 22 (parts listing).
  7. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-02, August 1996, topics 1.12-1.14 and 2.10-2.12 (parts lists). PDF.
  8. ↑ 8.0 8.1 IBM PC Institute, Personal Systems Reference: IBM ValuePoint, 1992 to 1995 – withdrawn, pp. 3, 6, 9, 12, 13. PDF.
  9. ↑ IBM, "IBM ValuePoint - Troubleshooting guide" (6384, version 1.13A.1, 1993), Service Hints & Tips JBAR-3QJS5D, section VIII items 1-2. kev009 mirror. Retrieved 2026-09-30.
  10. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, p. 6 (Power Supply).
  11. ↑ IBM, PS/ValuePoint Hardware Maintenance Manual, S61G-1423-01, September 1993, p. 42 (Hard Disk Drive Specifications).


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