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Fujitsu FM Towns (& FM Towns Marty)

The first consumer computer with a built-in CD-ROM drive (1989): a 386 base, hardware sprites and FM + PCM sound → impressive arcade ports (After Burner, Galaxy Force). Spun off as a console, the FM Towns Marty (1993). Repair: CD drive, recap, battery.

FM Towns (à gauche) et X68000

FM Towns (à gauche) et X68000 — photo by htomari, CC BY-SA 2.0 (Wikimedia Commons).

Identification / models

Model Year CPU Note
FM Towns Model 1 / 2 1989 386 @ 16 MHz built-in CD-ROM (a consumer first)
FM Towns II (UX/CX/HR/MX…) 1991-93 386/486 faster iterations
FM Towns Marty 1993 386SX console (FM Towns base) → CD games

Architecture

  • 386 CPU (486 on later IIs); hardware sprites + planes; YM2612 (FM) + PCM (RF5C68) sound — close to arcade sound.
  • Built-in CD-ROM (caddy type) + a 3.5″ floppy drive.

Repair (technician)

  • CD-ROM drive: caddy mechanism, loading belt, ageing laser → optical cleaning; an ODE alternative for preservation (see ODE mods).
  • Recap: PSU and board electrolytics → Recap.
  • Battery (CMOS/RTC) leaking → remove/replace, repair traces → backup batteries.
  • 3.5″ floppy drive: mechanism → clean / Gotek.
  • Marty: a console → same points (CD, recap, battery) + controllers/connectors.

Procedure — a dead computer, step by step ✅

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
CD not read belt / laser / caddy Clean optics, belt, ODE
Instability / crashes PSU/board caps Recap
Wrong clock / corrosion CMOS battery Remove, repair traces
Floppy not read 3.5″ mechanism Clean / Gotek

Modernisation & mods — what to buy, how

Leaking RTC battery + recap

Remove/replace the RTC battery (it leaks and eats the board) → lithium + diode (no recharge), clean/repair traces. Recap the PSU and board. (The Marty shares these points.)

Modern storage - CD → ODE 🟡: an optical emulator replacing the caddy CD drive (aging laser/belt) → images from SD/USB. → ODE mods. - SCSI → BlueSCSI / SCSI2SD 🟢: FM Towns with SCSI accept an SD card as a SCSI disk. - 3.5″ floppy → Gotek + FlashFloppy 🟡 (.bin/.d88 images).

Video - RGB output switchable 15/31 kHz per software 🟢 → SCART/VGA then OSSC / RetroTINK or RGB2HDMI for crisp digital.

⚠️ Do not host games/BIOS — 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.