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Sharp X1D General Maintenance

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Sharp X1D
Sharp X1D in metallic silver. The 3-inch drive is at the left of the front panel (photo: Japanese Vintage Computer Collection, hachibitto.com)

The Sharp X1D (CZ-802C, 1983) has a mains power supply, a 3-inch compact floppy drive and a NiCd clock backup cell inside the main unit, and a separate keyboard on a coiled cord.[1] The first job on any X1D is the NiCd cell, because a leaking cell damages the main board.

Before you start

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Warning: the X1D runs from AC 100 V mains through a power supply inside the main unit. Unplug it before opening the case.

Sharp rated the X1D at AC 100 V ±10 %, 50/60 Hz, and 49 W.[1] Outside Japan, run it from a step-down transformer rated well above 49 W. Sharp specified an operating range of 10 to 35 °C and 35 to 75 % relative humidity.[1]

NiCd clock battery

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X1 Center lists a 2.4 V 30 mAh backup battery on the X1D, and Sharp's specification describes it as a built-in NiCd cell that keeps the clock running.[2][1] X1 Center describes how these cells fail in X1 machines: electrolyte and gas escape, the board's solder resist turns rough, then the liquid soaks through the plated holes and dissolves the copper until tracks oxidise and break.[3]

  1. Open the case and find the cell on the main board. Look for green or white crust on it and on the board around it.
  2. If the clock does not need to keep time when the X1D is unplugged, remove the cell. X1 Center suggests removing it or fitting a 5.5 V supercapacitor in its place.[3]
  3. Clean any residue from the board, then check the plated holes nearby. On a first-model X1, X1 Center found holes that looked sound but released brown oxidised copper when reheated, and re-tinned them all.[3]
  4. Check each track that runs past the old cell position for continuity with a meter. Repair broken tracks with wire.

See Battery Explosion, Capacitor or Corrosion Damage for cleaning damaged boards.

3-inch floppy drive

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The internal drive is an MSHD200A01, a 3-inch double-sided double-density drive that does not move its head to track 0 by itself at power-on. Its interface lines have 820 Ω terminators.[4] X1 Center has not confirmed its step rate.[4]

  • Clean the head with isopropyl alcohol on a lint-free swab, and check that the spindle turns freely by hand with the power off. General drive procedures are in Floppy Drive Repair.
  • The drive's connector on the main board is soldered in place, so a faulty internal cable or connector has to be repaired on the board; it cannot be swapped.[4]
  • Blank 3-inch disks are hard to find. One owner loads BASIC and games on an X1D from an HxC floppy emulator.[5]

Keyboard

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The X1D keyboard is the first X1's keyboard without the cassette control keys.[6]

  • Check the coiled cord. On X1 keyboards the outer sheath whitens and crumbles, and the cord carries +5 V.[7] One X1D owner found the cable frayed and unreliable.[5]
  • To replace the cord, remove the six screws in the base of the keyboard, unplug the cord's three-pin connector from the keyboard board and pull out the pin that holds the strain relief. X1 Center used an ordinary 3.5 mm audio cable as the replacement.[7]
  • Clean the keyboard jack on the computer with contact cleaner. If the keyboard works only when the plug is pushed one way, reflow the jack's solder joints.[8]

Checklist

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  1. Remove or replace the NiCd cell and inspect the board around it.
  2. Check the mains rating label and use AC 100 V.
  3. Clean the case, keyboard and keycaps with a damp cloth; blow dust out of the main unit with the mains unplugged.
  4. Inspect the keyboard cord and jack.
  5. Clean the 3-inch drive head and check the spindle.
  6. Power up with the keyboard and an RGB monitor and check that the IPL menu appears. See Normal start-up.
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References

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  1. ↑ 1.0 1.1 1.2 1.3 Oh!MZ, November 1983, p. 26, Table 1, "パーソナルコンピュータ(CZ-801C/802C)仕様": 3-inch compact floppy drive, double-sided double-density, 320 KB; clock built in, on the X1D backed up by a built-in NiCd cell; AC 100 V ±10 %, 50/60 Hz; power consumption 49 W (X1D); operating temperature 10 to 35 °C, humidity 35 to 75 %; the text adds that one more 3-inch drive fits inside and that the X1D has an interface for the 5¼-inch CZ-800F and a cassette recorder. Scan on the Internet Archive, item oh-mz-1983-08-12, file Oh!MZ_1983-11.
  2. ↑ 搭載チップセット, X1 Center—link(accessed 2026-10-21) CZ-802C (X1D): backup battery 2.4 V 30 mAh; RTC µPD1990AC. The first X1 (CZ-800C) has the same 2.4 V 30 mAh battery; the X1F and X1G have none.
  3. ↑ 3.0 3.1 3.2 時計バックアップ用ニッカド電池, X1 Center—link(accessed 2026-10-21) NiCd clock backup cells leak electrolyte and gas through age or over-discharge; the resist surface roughens, then the liquid penetrates the through-holes and dissolves the copper, and tracks oxidise and break; if the clock backup is not needed, remove the cell or replace it with a 5.5 V supercapacitor. On a CZ-800C main board the through-holes near the transistor beside the cell had turned black, and applying fresh solder to them brought out brown liquid (oxidised copper). On an X1turbo III sub-board the vias under the cell were black, re-tinning them took about 15 minutes, and one track had broken.
  4. ↑ 4.0 4.1 4.2 X1/turbo/Zシリーズ搭載FDDインターフェース仕様, X1 Center—link(accessed 2026-10-21) CZ-802CR and CZ-802CS (X1D): one 3-inch 2D drive plus room for one more; MSHD200A01, Sharp part DMECF0003CE (silver model); add-on drives CZ-31FR and CZ-31FS. MSHD200A01: 3-inch 2D, step rate not confirmed, 820 Ω terminator, no restore at power-on. X1D floppy interface: no DMA, 2HD or FM; discrete TTL VFO; external connector terminators 150 Ω; the internal drive cable cannot be changed, because the internal connector is soldered directly to the board.
  5. ↑ 5.0 5.1 Sharp X1 D, Japanese Vintage Computer Collection (hachibitto.com)—link(accessed 2026-10-21) Owner's account: at power-on the power indicator and floppy drive light came on and the drive light went out when no disk was found; the IPL screen appeared and the TV timer could be set; the keyboard cable was frayed and unreliable though usable; 3-inch disks are hard to find, so BASIC and a game were loaded from an HxC floppy emulator.
  6. ↑ X1 (コンピュータ), Japanese Wikipedia—link(accessed 2026-10-21) X1D: keyboard the same as the first X1's apart from the removal of the cassette control keys. Separate keyboards connect with a 3-pole 3.5 mm plug.
  7. ↑ 7.0 7.1 X1/turbo用キーボードケーブルの劣化と交換, X1 Center—link(accessed 2026-10-21) The coiled cord of X1 and X1turbo keyboards whitens and its sheath crumbles; the keyboard line carries +5.0 V, so a short is dangerous; replace it with 3.5 mm audio cable; six screws on the underside hold the keyboard case; the cord ends in a three-pin connector on the keyboard board and its strain relief is held by a metal pin; the original strain relief can sometimes be reused by drilling out the old cord.
  8. ↑ キーボードコネクタの半田剥離, X1 Center—link(accessed 2026-10-21) Keyboard connector problems are one of the most frequent faults on X1, turbo and Z machines; light oxidation responds to contact cleaner; a keyboard that works only when the plug is pushed one way usually has a cracked joint on the connector board.


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