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Sharp X68000 Compact General Maintenance

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Sharp X68000 XVI CZ-634C front (htomari)
An X68000 XVI, the twin-tower model with the same processor as the Compact (photo: htomari, CC BY-SA 2.0). No freely licensed photograph of the Compact was found.

The Sharp X68000 Compact (CZ-674C) was sold from February 1992.[1] Its power supply, the SH7, its 3.5-inch drives and its keyboard are all different from the tower models', and little repair information has been published for any of them.[2][3] The notes below cover what is known.

Before you start

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  • The X68000 series runs from 100 V AC.[4] In countries with 220 to 240 V mains, use a step-down transformer and check its output before connecting the computer.
  • The Compact has no main switch on the rear; the front switch is the only power switch.[4] Sharp's manuals for the original X68000 and the XVI ask for at least 10 seconds between switching off and switching on again.[5][6]
  • Treat the supply's primary side as live after unplugging. The SH4 of the tower models holds more than 100 V DC there after the plug is pulled.[7]

Power supply

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The SH7 is shared with the X68030 Compact and differs from the towers' SH4. Its T2 transformer is not interchangeable.[2][3] No capacitor list has been published; see the Sharp X68000 Compact Capacitor Replacement Guide for how to record and replace the parts. Sharp's reissued service manual for the X68030 Compact covers the same type of supply.[3]

Floppy drives

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The 3.5-inch drives eject discs automatically.[4] Poe lists their parts as K36-0312-06, K36-0339-01 and Sankyo MSBA020K02, and treats the Compact drive as a type of its own, shared only with the X68030 Compact.[2][8] Sharp's CZ-6FD5 adds an external 5.25-inch drive.[4] See Floppy Drive Repair for general drive cleaning.

Memory settings

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The 16 KB SRAM holds the memory switch settings and is kept alive by a backup cell.[4] If the settings are corrupt, they can be cleared from Human68k; see the Troubleshooting Guide.

Upgrades and modified machines

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  • The MC68000 is soldered in on the Compact, where the other X68000s have a socket.[4] Check the board before planning a processor swap.
  • Memory: Sharp's CZ-6BE2D board, with a CZ-6BE2B module, and the CZ-6BP2 coprocessor; Tsukumo's TS-6BE6DE 6 MB board with an MC68882.[4][9]
  • Mankai Seisakusho sold a modified Compact, the RED ZONE, that switches between 10, 16 and 24 MHz. Units that would not run reliably at 24 MHz were set back to 16 MHz and sold as the RED ZOMBIE.[9][4] If you have a RED ZONE, run it at 16 MHz while testing.

Case cleaning

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Sharp's manuals for the original X68000 and the XVI both say to wipe the case with a soft cloth dampened with water or a mild neutral detergent, and never to use benzine or thinner.[5][6] The Compact's case is plastic, and its X68000 badge is printed on.[4] Clean round the badge gently.

Checklist

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  1. Confirm the mains supply is 100 V.
  2. Open the SH7, record every capacitor, and recap it.
  3. Clean and check the floppy drives.
  4. Clear and re-enter the SRAM settings if they are corrupt.
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References

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  1. ↑ X68000, IPSJ Computer Museum, Information Processing Society of Japan—link(accessed 2026-10-21) Series table: X68000 CompactXVI, CZ-674C, February 1992.
  2. ↑ 2.0 2.1 2.2 SHARP X68000 修理– Poe—link(accessed 2026-10-21) CompactXVI and X68030 Compact SH7, "T2 transformer not interchangeable"; Compact floppy drive parts K36-0312-06, K36-0339-01, Sankyo MSBA020K02; keyboard DSETK0025CE01 (CMA-600N0).
  3. ↑ 3.0 3.1 3.2 X68000シリーズ電源のハンダ面から見た抵抗配置図– Kunihiko Ohnaka (kunichiko), 2020-10-10—link(accessed 2026-10-21) Compact CZ-674C and X68030 Compact SH7; most twin-tower models SH4. Sharp's reissued service manuals on COCORO BOOKS include the X68030 Compact CZ-300C/CZ-310C.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 X68000, Wikipedia (Japanese)—link(accessed 2026-10-21) Power 100 V AC; no rear main power switch on the Compact, PRO and PRO II; 16 KB battery-backed SRAM for the memory switch settings; Compact models with auto-eject 3.5-inch drives and a plastic case, the X68000 badge printed in white; MPU socketed on every model except the Compact. Options: CZ-6BE2D 2 MB board for the CZ-674C with the CZ-6BE2B module; CZ-6BP2 coprocessor for the CZ-674C with the CZ-6BE2D; CZ-6FD5 external 5.25-inch drive for the Compact. Mankai Seisakusho's Compact XVI RED ZONE ran at 24 MHz; RED ZOMBIE units, which could not stand 24 MHz, were returned to 16 MHz and sold cheaply.
  5. ↑ 5.0 5.1 Sharp, X68000 取扱説明書 for the CZ-600C (File:Sharp X68000 CZ-600C Owner's Manual.pdf), 4.2 and 4.3, printed pages 19 and 20 (PDF pages 33 and 34): soft cloth with water or neutral detergent, no benzine or thinner; at least 10 seconds between off and on.
  6. ↑ 6.0 6.1 Sharp, X68000 XVI・XVI HD 取扱説明書 (File:Sharp X68000 XVI Owner's Manual.pdf), 4.2, printed page 23 (PDF page 39): soft cloth with water or diluted neutral detergent, no benzine or thinner; 4.3, printed page 24 (PDF page 40): 10 seconds or more between off and on.
  7. ↑ X68kXVI HDの電源リペア– Fram, 2015-05-23—link(accessed 2026-10-21) The SH4's primary side holds more than 100 V DC after the plug is pulled.
  8. ↑ SHARP X68000 FDD K61432-71 K61432-72 K-61435-72 修理– Poe, 2020-02-23—link(accessed 2026-10-21) Four broad types of X68000 floppy drive, one of them the 3.5-inch drive of the X68000 Compact and X68030 Compact.
  9. ↑ 9.0 9.1 SHARP X680x0– DEKO—link(accessed 2026-10-21) REDZONE, a clocked-up X68000 Compact from Mankai Seisakusho switching between 10, 16 and 24 MHz; TS-6BE6DE, a 6 MB memory and FPU board for the X68000 Compact with an MC68882, sold by Tsukumo.


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