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Recap guide

Recap the IBM PS/1 and PS/2

PS/2 planars and supplies use electrolytics that fail, and PS/2 floppy drives use small SMD ones.

Open the interactive checklist Tick off each capacitor as you replace it. It saves in your browser.

Worth a recap. Reports say it is a common and useful fix on this machine.

Which board do I have?

Boards changed during production. These notes come from the linked sources, and many are only partly documented, so check the board in front of you.

  • PS/2 Model P75 (8573) planar (Medium confidence). How to tell: Planar capacitors are numbered C1 to C12. Capacitors: Planar: C1 10uF 25V, C2 and C3 22uF 25V, C4 10uF 16V, C5 to C7 10uF 25V, C8 10uF 16V, C9 10uF 25V, C10 10uF 16V, C11 33uF 25V, C12 10uF 25V; plasma adapter board has 2x 33uF 16V and 4x 10uF 16V. Capacitor list differs from other revisions: not known. Source
  • PS/2 8580 supply by Schrack (Medium confidence). How to tell: IBM 90X9109 or 15F6551, Schrack EP071063-A, 225W. Capacitors: A failed 3300uF 16V filter cap caused chirping. Capacitor list differs from other revisions: not known. Source
  • PS/2 8580 supply by Plessey (Low confidence). How to tell: Same IBM part numbers but Plessey built with a riveted case. Capacitors: No separate values. Capacitor list differs from other revisions: not known. Source

Where to start

Clues from write-ups and forum threads, not a diagnosis. Low confidence means one thread or one repair; high means several write-ups agree.

  • Model 8573 (P75) (Medium confidence). A table lists failing planar and plasma adapter caps by location on the P75, a portable but a good example. Source
  • Model 80 supply (Low confidence). One repair found a shorted 3300 uF filter cap in the Schrack 8580 power supply. Source
  • Floppy drive SMD caps (Low confidence). A forum thread lists floppy drive caps with sample values, with a caution that values differ by drive. Source

Tips, tales and maybes

Found in write-ups and forum threads. These are other people's reports, not tested by us. Check part references and values against your own board.

  • Story: PS/2 80 floppy drive that would not read (Medium confidence). A Mitsubishi floppy drive in a PS/2 Model 80 stopped reading, with the LED lit but no spindle. Of five electrolytics on the drive board only one was in spec, two were open and two were out of spec, and replacing them fixed it. Others said it affects similar drives. Source
  • Tip: 55SX: clear CMOS after a battery swap (Low confidence). On a PS/2 55SX the poster replaced corroded caps on the 80MB drive and the dead Dallas RTC battery, and the machine only booted after clearing CMOS with DEBUG commands (o 70 13 and o 71 00) following the reference disk autoconfiguration. Source

Before you start

  • Boards changed during production. Check your board number against the guides before you order parts.
  • A mains power supply can hold a dangerous charge. If you are not trained to work on one, have a professional do it.

Guides we used

This page and the interactive bench are built from these. They have the photos and the full detail, so please read them and support their authors.

The capacitor list

We have not checked a capacitor list for this machine yet, so none is shown. Follow the guide above for your board, then add the capacitors in the interactive checklist and it builds a shopping list for you.

Skip the sourcing

While you are in there

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Steps, tools and safety

The steps, the tools in top, middle and budget picks, and the safety list are the same for every machine, so they live on one page: How to recap, step by step.

Values are shown as published in the guides above, and boards changed during production. Check the board in front of you. A recap involves hot tools and, on some machines, dangerous voltages. You do it at your own risk.

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