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Recap guide

Recap the Apple II power supply

The original Astec-type supply has paper-style line-filter caps that pop and electrolytics that dry out. The power supply is the part to recap.

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.

  • Astec AA11040 (Medium confidence). How to tell: Astec supplies are described as gold colored with a solder mask and user replaceable fuses. Capacitors: An Applefritter thread says a listing for the AA11040 shows only a 0.1uF RIFA while other variants used both 0.1uF and 0.22uF. Capacitor list differs from other revisions: yes. Source
  • Astec AA11040B and AA11040C (Low confidence). How to tell: Model number printed on the Astec case. Capacitors: Suggested RIFA substitute ECQ-U2A104KL needs 20 mm lead spacing; a poster says the small 220uF at C12 is a known weak point. Capacitor list differs from other revisions: not known. Source
  • Astec AA11042C (IIe) (Low confidence). How to tell: Model number printed on the Astec case. Capacitors: Thread points to high voltage (200V plus) AC side caps and a RIFA line filter cap, with X2 replacements advised. Capacitor list differs from other revisions: not known. Source
  • Dynacomp supply (Low confidence). How to tell: Mid 1980s Dynacomp units often have bare aluminum housings; used in later IIe and Platinum IIe. Capacitors: Some earlier Dynacomp units used X1 rated safety caps instead of X2. 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.

  • Popping line-filter caps (Medium confidence). A forum thread recommends swapping RIFA-style X-rated line-filter caps (0.1 and 0.22 uF seen) for polypropylene film X2 parts. It gives only the film values. Source
  • Dried-out electrolytics (Low confidence). A community thread says to replace the electrolytics as well as the safety caps, but gives no part list. 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.

  • Watch out: Stored charge in the supply (Medium confidence). A poster warns that supply capacitors can hold a charge after use, so let the unit sit unplugged for a while before opening it. Polarity matters only on the electrolytics. Source
  • Tip: Choosing replacements (Medium confidence). The thread suggests replacing the electrolytics and the safety (X) caps, matching uF, using equal or higher voltage, matching lead spacing, keeping height equal or shorter, and preferring low ESR. Source
  • Tip: Rectangular line filter cap is the smoker (Medium confidence). In an Apple IIe supply thread, posters say the rectangular RIFA-style line filter cap is the usual cause of the magic smoke and should become a mains-rated X2 part. They suggest 105C electrolytics such as Nichicon PW or Panasonic FR, one cap at a time. Source
  • Watch out: Test the supply on its own (Medium confidence). The thread says to check all output voltages with the supply disconnected from the motherboard, because a failing supply can take the board with it. Brown goo inside the case is a sign something has already failed. Source
  • Tip: Some Apple II+ supplies have no RIFA caps (Medium confidence). In a thread on a stored Apple II+ supply, a reply says that version has no RIFA filter caps and that only the +5V is fully regulated, the other rails being rectified and smoothed. Unloaded readings of about +11.6V and -10.4V were judged acceptable by posters. 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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