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Apple II (II / II+ / IIe / IIc / IIGS)

The founder of US micro gaming (1977): a 6502, expansion slots, a Disk II drive — the platform of Wizardry, Karateka, Prince of Persia. Repair: RIFA/PSU, the IIGS battery, the Disk II drive, slot contacts.

Apple IIe

Apple IIe — photo by Bilby, CC BY 3.0 (Wikimedia Commons).

Identification / models

Model Year CPU Note
Apple II / II+ 1977-79 6502 the origin; linear then switching PSU
Apple IIe 1983 6502 the most common, full keyboard
Apple IIc 1984 65C02 compact, external PSU
Apple IIGS 1986 65C816 (16-bit) Ensoniq sound, ⚠️ leaking battery

Clocks & frequencies ✅

Component Frequency Role / scope
MOS 6502 1,023 MHz CPU — soit 2/7 de la sous-porteuse couleur NTSC
Oscillateur maître 14,31818 MHz divisé par 14 pour l'horloge CPU, et par d'autres rapports pour la vidéo

The whole machine's timing derives from a single 14.31818 MHz oscillator: CPU clock, video transfer counters and colour signals all come from it. A fault on that oscillator therefore affects everything at once.

Why this matters in repair

A clock that is missing or off-value on a frequency counter points straight at the crystal, its divider chain or the component it feeds — the fastest starting point on a machine that will not boot. Source: Wikipedia (CC-BY-SA).

Repair (technician)

RIFA caps & switching PSU

The RIFA (mains filter) caps in the switching PSUs (II+/IIe/IIc) smoke/explode with age → replace; recap the PSU if voltages are unstable → Recap.

Apple IIGS battery

The IIGS has a soldered (clock/settings) battery that leaks and eats the board → remove/replace it (remote holder) → backup batteries.

  • Disk II drive (5.25″): speed adjustment (300 rpm) + head cleaning; a fragile ribbon cable.
  • Socketed chips: diagnose by substitution (RAM, 6502, ROM); oxidised expansion slot contacts (language/80-column/controller cards) → clean.
  • Keyboard: contacts / keys → clean.
  • Video output: stock composite → RGB mods per model.

Common faults

Symptom Likely cause Lead
Smoke / bang at power-on mains RIFA Replace the RIFA
Instability / crashes PSU (caps) / RAM Recap PSU, substitute RAM
Corrosion (IIGS) leaked battery Remove, repair traces
Floppy not read Disk II speed / head Adjust speed, clean
Card not detected slot contacts IPA clean, reseat

Modernisation & mods — what to buy, how

PSU RIFA + leaking IIGS battery

The PSU's RIFA filter caps smoke/explode with age → replace them on acquisition. On the IIGS, the soldered battery leaks and eats the board → relocate it (external coin-cell holder), clean/neutralize, repair traces.

Modern storage - Floppy Emu (BMOW) 🟢: emulates Disk II and a SmartPort hard disk from an SD card (external box on the drive connector); CFFA3000 🟢 (CF/USB as a hard disk, Apple slot card); A2Pico/BOOTI 🟢.

Video - Composite NTSC output 🟢 → an upscaler; period RGB cards (Apple RGB/Video-7) or modern ones 🟠 for RGB/VGA.

Expansion - 80-column / language cards (remade) 🟢, Mockingboard sound (remade) 🟢; the //e has free slots.

Reliability: few electrolytics on the Apple II board; clean the IC sockets.

⚠️ Do not host ROMs/games — method only.

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.