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Apple Macintosh compact (128K → SE/30)

The "toaster" Macs (1984-1991): 68000/030, an integrated 9″ B&W screen, a major collector's item. Few games versus the games-focused micros, but strong restoration demand. A high-risk repair: internal CRT + analog board, a leaking PRAM battery.

Macintosh Plus

Macintosh Plus — photo by Maksym Kozlenko, CC BY-SA 4.0 (Wikimedia Commons).

Identification

Model Year CPU Note
128K / 512K 1984 68000 @ 8 MHz the founders, soldered RAM
Plus 1986 68000 SCSI, expandable SIMM RAM
SE / SE/30 1987-89 68000 / 68030 SE/30 = the most powerful compact, highly prized
Classic / Classic II 1990-91 68000/030 budget end of the line

Repair (technician)

CRT + analog board = high voltage

The compact Mac is an all-in-one: the CRT, EHT and analog board (PSU + deflection + video) are inside. Discharge the EHT and follow CRT safety before any work.

Leaking PRAM battery (½ AA 3.6 V)

The soldered/holder PRAM battery leaks and eats the logic board (especially the SE/30). Remove it right away, clean/neutralize, repair traces → backup batteries.

  • Recap the analog board: dried caps → screen folded to a line, "singing flyback", won't power on → Recap (community-documented analog kits).
  • Recap the logic board (SE/30, Classic II): leaking SMD caps → dead sound, checkerboard, "simasimac" → a full recap + cleaning fixes most "dead Macs".
  • Floppy drive (400/800K/SWIM 1.44 MB): mechanism / lubrication → service; emulators (Floppy Emu) common.
  • Flyback: whine / unstable image → tired component (rare, hard to replace).

Step-by-step disassembly procedures ✅

1 procedures transcribed from the iFixit guides, with difficulty and estimated time.

Procedure Difficulty Time
Macintosh Classic disassembly Moderate 30 minutes
Macintosh Classic disassembly

The Macintosh Classic is a computer mounted in a simple way but with two different types of screws (Torks and Philips) put in the most unattainable places. — Templates : Model Number: M0420 and M1240

  1. Turn the Mac so the screen is face-down
  2. Put a cloth under the screen to not scratch the screen.
  3. Unscrew the four Torx screws.
  4. Two screws are on the bottom side near the ports, the other two are Hidden in the handle.
  5. WARNING, IF YOU COME INTO CONTACT WITH THE DISCHARGE FROM THE CRT YOU RISK DYING, We recommend looking for a tutorial on YouTube
  6. Connect a flat screwdriver to the CRT ground cable (black cable attached to the screw) with an alligator cable.
  7. Slowly push the screwdriver under the red suction cup connected to the CRT and touch the metal part with the screwdriver.
  8. The motherboard has no screws, so it can be removed by pulling upwards.
  9. Make sure to disconnect all cables.
  10. Remove the four screws and pay attention to the two hidden screws.
  11. The Floppy lock and Disk go away easily.
  12. WARNING - The POWER SUPPLY may still contain current inside it. Do not touch any capacitors on the power supply
  13. Unscrew the two screws that secure it to the chassis and remove the connected cables.
  14. To remove the Chassis you must use the same Torx 15 screwdriver as the handle.
  15. Unscrew the four screws and the Chassis can be removed.
  16. CAUTION: The cathode ray tube is under pressure, avoid scratching or breaking it.
  17. To remove the CRT, simply unscrew the four screws placed at the corners.

Source, licence and scope

iFixit guides, under Creative Commons BY-NC-SA — attribution, non-commercial, share-alike. Only the text is reproduced; the step photos stay on iFixit. ⚠️ These guides target the model named in the title: on another revision, the screws and the order of removal may differ.

Procedure — a dead computer, step by step ✅

There is a CRT inside this machine

The tube holds its charge with the machine unplugged, and on these all-in-ones the analogue board sits right where your hands go. Discharge it, or work on the logic board out of the case. → CRT safety

What this adds

Ordered for a home computer: what kills these is its power supply, its battery, its capacitors, its socketed RAM and its keyboard — roughly in that order, and well before the CPU. → PCB diagnosis

1. The power supply — measured before it is plugged in. This is the one step not to swap around. On a machine of this age a supply does not simply stop: a 5 V regulator that fails high puts 7, 9, 12 V onto the bus and takes the RAM and the custom chips with it. Measure every rail off the machine, under a dummy load if you can, and only then plug it in.

2. The battery — before anything else. This page documents a cell that leaks — check on the page whether your model is one of the affected ones, several of these pages cover a whole range. Its electrolyte eats the copper underneath and keeps eating while the machine sits in a cupboard, so it comes out first, before any diagnosis. Neutralise, clean, then check continuity on the tracks around it — a machine that no longer boots after storage is very often this and nothing else. → Backup batteries

3. Capacitors. Recap is the default on these machines, not a last resort — and on the supply first, since that is what protects everything else. → Recap

4. RAM, on its sockets. These machines were built to be repaired: the RAM, and often the logic, sit in sockets. Reseat everything first — thirty years of oxide is a classic no-boot. Then swap chips: a bad RAM chip usually gives a repeatable pattern of garbage or a screen frozen at a fixed character.

5. The keyboard. A console does not have one; a computer's is a wear part. A membrane keyboard fails as whole dead rows or columns — that is the membrane, not the machine. A mechanical one wants its contacts cleaning, not replacing. Check this page: the failure mode is often documented per model.

6. Storage — tape or disk. Both often come down to the same things: a dirty head, and for tape the azimuth and a belt turned to tar. ⚠️ On the floppy side, check whether the mechanism actually has a belt before looking for one: many do, but some drives are direct drive, and hunting a belt that isn't there means stripping a drive for nothing. A machine that boots but loads nothing is a drive fault, not a logic fault — do not go looking on the board for it.

7. Video output. RF, composite, RGB or a dedicated monitor, depending on the machine (see Identification). Test with something else before you conclude: a period modulator and a modern TV disagree far more often than either is broken.

8. Still nothing. Now the logic: rails on the board, reset, clock, bus. → PCB diagnosis

Common faults

Symptom Likely cause Lead
Corrosion / dead sound / "simasimac" SMD logic-board caps (SE/30) Recap + clean
Screen folded to a line / no power analog-board caps Analog recap
Corrosion near the battery leaking PRAM Remove, neutralize, repair
Floppy not read mechanism / SWIM Service / Floppy Emu

Modernisation & mods — what to buy, how

Leaking PRAM battery + CRT high voltage

Remove the PRAM battery without delay (it leaks and eats the board — SE/30 in particular) → clean/neutralize, repair traces. The recap targets the logic board (SE/30, Classic II) and the analog board (community kits). ⚠️ The compact Mac has a CRT: lingering high voltage (flyback) → discharge the tube before opening → CRT safety.

Modern storage - Floppy Emu (BMOW) 🟢: emulates the 400/800 KB and 1.44 MB drives and the HD20 hard disk from an SD card (external box) → direct boot, no more tired floppies. The flagship compact-Mac mod. - BlueSCSI / SCSI2SD 🟢 (Plus, SE, SE/30…): an SD card as a SCSI hard disk; PiSCSI/RaSCSI (Raspberry Pi) 🟡 adds disks, networking, virtual CDs. - ROM-inator 🟡 (SE/Plus): a replacement ROM (socketed) with RAM-disk/HD20 boot.

Video / display - Integrated 9″ B&W screen: no "color mod". On the SE/30 (030 PDS slot) you can add a video/Ethernet card for an external monitor and networking.

Reliability: recap 🟠 (logic + analog board); battery removal 🟡.

  • 030/040 accelerators and RAM upgrades 🟠 for slotted models.

⚠️ Do not host ROMs/System — method only.

Archived technical documentation ✅

Manufacturer documentation archived locally: schematics, block diagrams, expected voltages, parts lists. The reference when a symptom matches no known fault.

  • Macintosh port pinouts — PDF
  • Macintosh IIvx / IIvi / Performa 600 — PDF
  • Macintosh Plus — PDF
  • Macintosh Classic — PDF
  • Macintosh Classic II — PDF
  • Macintosh II — PDF
  • Macintosh IIcx / IIci / Quadra 700 — one Service Source covering all three machines — PDF
  • Macintosh IIsi — PDF
  • Macintosh LC — PDF

Status

Manufacturer documents kept for preservation (machines out of production for decades), with no explicit licence — the same position as for the cabinet manuals already archived here.

See also

Sources & attribution

Review & corrections

How this space is used

Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.

Reading is open to everyone; posting requires signing in with Discord. Reports from the wiki's declared reviewers are handled first; anyone else's are read too, but go through a human before anything is changed.