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Recap guide

Recap the Mac 128K, 512K, Plus and SE analog board

The analog board's electrolytics and the line-filter caps are the standard recap on compact Macs.

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.

  • Analog board 630-0102 (120V) (Medium confidence). How to tell: Assembly number on the top front edge opposite 820-0082-B. Capacitors: Console5 kit has 21 caps from 0.1uF to 4700uF, 10 to 275V; Console5 sells one US and one international kit for 128K through Plus. Capacitor list differs from other revisions: not known. Source
  • Analog board 630-0108 (240V) (Medium confidence). How to tell: Assembly number for the 240V analog board; the PCB itself is the same 820-0082 style board marking. Capacitors: Recap list has 25 positions, 3.9uF to 4700uF, 10 to 250V; wire W12 selects 120V or 240V. 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.

  • 630-0108 board list (Medium confidence). A forum thread gives a full list for the 630-0108 board with Mouser part numbers. Board revisions differ, so match your board number. Source
  • 630-0102 board list (Medium confidence). A 21-cap list covers the 630-0102 board (Mac 128K analog board 820-0082-B) and mentions a pre-built kit option. Source
  • Line-filter caps (Low confidence). One recent full restoration explains its ESR choices and swapped the line-filter caps for X1-rated ones. It 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.

  • Tip: Ticking analog board is often not a capacitor (Medium confidence). On a Mac Plus whose analog board just ticks, posters list a failing flyback, the BU406 output transistor (Q3), the U3 regulator and diodes CR15, CR17, CR20 and CR21 ahead of capacitors, with a full recap as a later step. The owner's board stayed dead after replacing Q3 and the flyback. Source
  • Watch out: Fading optocoupler can run the 5V rail away (Medium confidence). A 128K restoration diary says the analog board optocoupler LED fades with age, which can make the supply run away to overvoltage and kill the digital board. The author replaced it with a 4N35 and recalibrated the 5V feedback, and also swapped the Rifa line caps for X-rated modern parts. Source
  • Story: Drifted resistors and tired flyback (Low confidence). The same diary found large 1W resistors that had drifted badly (one 33K reading over 45K), degraded flyback potting, and chose regular-ESR caps on the supply secondary to limit inrush. These are one author's choices rather than a standard recipe. Source
  • Story: Wrong kit voltage and C3 failing after a new flyback (Medium confidence). A Mac Plus owner with a whining board used a 240V parts list because the first kit was for 120V models. After fitting a new flyback, C3 (between +12V and the flyback) failed violently, and the BU406 and diodes CR1 and CR5 were also replaced. 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.
  • A tube and its high-voltage circuit can hold a lethal charge. Do not open the tube, and leave the analog board to a professional.

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

Affiliate links. As an Amazon Associate I earn from qualifying purchases. These links only search by name. Disclosure

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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