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Sharp X68000

The "arcade at home" machine (1987): a 68000 + graphics customs (sprites, planes, 65536 colours) and YM2151 + OKI ADPCM sound — exactly the toolkit of period Capcom boards, hence near-perfect ports (Final Fight, SF2…). A cult "Manhattan" case. Emergencies: the PSU and the RTC battery.

Sharp X68000 (teardown)

Sharp X68000 (teardown) — photo by Dave Jones, CC BY 2.0 (Wikimedia Commons).

Identification / models

Model Year CPU Note
X68000 (Pro / ACE / EXPERT / SUPER) 1987-90 68000 @ 10 MHz the "twin tower" case
X68000 XVI 1991 68000 @ 16 MHz faster
X68000 Compact 1992 68000 @ 16 MHz smaller form factor
X68030 1993 68030 @ 25 MHz the last model

Architecture

Block Chip/role
CPU Motorola 68000 (68030 on the X68030)
Video Sharp customs: hardware sprites, multiple planes, scroll, 65536 colours
Sound Yamaha YM2151 (8-voice FM) + OKI ADPCM (MSM6258) — the arcade sound
Storage 2× 5.25″ drives + SASI/SCSI (HDD) per model

Repair (technician)

1) The PSU — the No. 1 fault

The X68000's switching PSU is notorious for dying (dead/leaking caps, drifting regulation) → no boot or instability. Recap the PSU (or fit a modern PSU / Pico) → Recap.

2) Leaking RTC battery

The clock battery leaks and eats the board → remove/replace it ASAP (lithium + diode) → backup batteries.

  • 5.25″ drives: tired mechanism / belt → Gotek (HD/FD emulator) for preservation.
  • Board recap: period electrolytics → recap if video/sound degrade.
  • Graphics customs: rare → corrupt video = test VRAM + buffers first, the custom next (donor).
  • Yellowing plastic (like much retro): cosmetic retrobright.
  • Video output: 15/31 kHz per mode → multi-sync monitor / SCART (video mods).

Original service manual ✅

Manufacturer manual archived locally. It typically carries the schematics, the block diagram, the expected voltages and waveforms, the parts list and the disassembly procedures — the reference when a symptom matches no known fault.

  • Sharp X68030 (CZ-147) — service manual — PDF

Status

A manufacturer document with no explicit licence, kept for preservation (machine long out of production). Source: Internet Archive.

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
No boot / unstable PSU (caps) Recap PSU / modern PSU
Corrosion near the clock RTC battery Remove, repair traces
Floppy not read 5.25″ mechanism Clean / Gotek
Degraded video/sound caps / customs Recap, substitution

Modernisation & mods — what to buy, how

Fragile X68000: recap + PSU + battery BEFORE anything

  • Recap is mandatory 🟠: the SMD caps leak and eat the board — the X68000 plague (clean the electrolyte, repair traces).

  • The original PSU dies → a modern PSU (documented PicoPSU / Mean Well kits) 🟠.

  • A leaking RTC battery → lithium + diode (no recharge).

Modern storage - SCSI → BlueSCSI / SCSI2SD 🟢: the X68000 is SCSI → an SD card as a hard disk (SCSI port); CF on later IDE interfaces. - Floppy → Gotek + FlashFloppy or HxC 🟡 (the eject mechanism breaks — see below).

Video - Switchable 15/31 kHz RGB output 🟢 → SCART/VGA then OSSC / RetroTINK or RGB2HDMI.

Mechanics & expansion - A broken floppy eject gear (classic defect) → a remade (3D-printed) gear 🟡. - 060turbo accelerator + RAM 🟠 for compatible models.

⚠️ 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.