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Sharp X1F General Maintenance

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Sharp X1F Model 10 interior
X1F Model 10 with the cover off. The power supply is the perforated box at the right rear and the data recorder sits behind the front panel (photo: AKIBA PC Hotline!, Impress)

The Sharp X1F is a 1985 desktop computer with its mains power supply inside the case, a built-in cassette data recorder on the Model 10 and a 5¼-inch floppy drive on the Model 20.[1] The parts that wear are the rubber in the data recorder, the floppy drive, the keyboard cord and the keyboard jacks.

Before you start

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Warning: the X1F runs from AC 100 V mains through a power supply inside the case. Unplug the mains lead before removing the cover, and keep fingers away from the power supply box until its capacitors have had time to discharge.

The X1F is a Japanese-market machine rated for AC 100 V.[2] Run it from a step-down transformer where the local mains is higher.

The rear panel carries the main POWER switch.[2] The front panel has POWER, TIMER, READ, WRITE, REW and FF indicators beside the tape counter.[3] The rear panel layout from left to right is the power switch, RGB output, TV control, printer, audio output, joysticks and keyboard, with the expansion I/O slots above.[4]

Opening the case

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Removing the outer cover exposes the main board and the data recorder mechanism; on the X1F this is enough to inspect the cassette belts, which on the first X1 meant taking most of the machine apart.[4] With the cover off, the photograph above shows the layout of a Model 10: the main board in the middle, the power supply in a perforated metal box at the right rear, the expansion slot frame across the back, and the data recorder behind the front panel.[5]

Photograph each cable before unplugging it. No screw count or disassembly order for the X1F has been published.

Data recorder (Model 10)

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The Model 10's built-in data recorder is a high-speed deck with electromagnetic control.[4] In decks of this type, X1 Center explains, one motor turns all the time the deck is working and solenoids switch its drive between head loading, play, fast forward and rewind.[6] No one has published belt sizes for the X1F's own deck. On the decks that X1 Center has repaired, the original X1's built-in recorder and the CZ-8RL1, the belts and rubber rings differ between the two, so measure the X1F's parts before ordering replacements.[6][7]

  1. Wash your hands or wear gloves. Grease from skin speeds the ageing of rubber belts.[6]
  2. Look at each belt with the cover off. A belt that has turned soft and sticky has to be scraped off its pulleys completely before a new one is fitted; on the first X1 the loading belt had melted onto the parts around it.[7]
  3. Check the tape counter belt. The counter carries the tape end sensor on the X1 decks, so a counter that does not turn makes the deck stop as soon as it starts.[6]
  4. Check the rubber ring that drives the take-up spool in play. A cracked ring leaves the spool still, and the computer reads that as the end of the tape.[7]
  5. Clean the heads and pinch roller with isopropyl alcohol on a swab.
  6. Do not spray solvent-based oil, silicone or contact cleaner into the mechanism. X1 Center lubricated a sticky gear shaft with dry PTFE after cleaning the old grease off with alcohol.[6]

Floppy drive (Model 20)

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The Model 20's drive is a TEAC FD-55BV-23, a 5¼-inch 2D drive.[8] Clean its heads and check the spindle and head stepper as described in Floppy Drive Repair. Sharp sold the CZ-52FE and CZ-52FR as the second internal drive for the grey and red machines.[8] The drive cable inside the Model 20 is a separate cable and can be replaced.[8]

Keyboard

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  • The keyboard cord on X1 and X1turbo keyboards loses its outer sheath with age. The cord carries +5 V, so replace a cracked cord before using the keyboard. X1 Center replaced one with an ordinary 3.5 mm audio cable, fitted through the original strain relief and terminated in the three-pin connector on the keyboard board; six screws hold the keyboard base.[9] The X1F's keyboard is the thin type introduced with the X1turbo, so check its cord the same way.[10]
  • If the keyboard works only when the plug is pushed one way, reflow the joints on the keyboard jack board in the computer. X1 Center lists cracked joints there as one of the most common faults on the X1, X1turbo and X1turboZ.[11]

Battery

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X1 Center lists no clock backup battery on either X1F model.[12] There is no cell to remove before storage, unlike the Sharp X1D.

Capacitors

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No capacitor values for the X1F have been published. See the Sharp X1F Capacitor Replacement Guide for what is known and how to record your own board.

Checklist

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  1. Check that the supply is AC 100 V or that a step-down transformer is in use.
  2. Clean the case and keycaps with a damp cloth, and blow dust out of the power supply vents with the machine unplugged.
  3. Open the case and look for swollen or leaking capacitors in and around the power supply box.
  4. Inspect the data recorder belts and the take-up ring (Model 10), or clean the floppy drive (Model 20).
  5. Inspect the keyboard cord and both keyboard jacks.
  6. Power up with only the RGB monitor and keyboard connected and check that the IPL screen appears before adding peripherals.
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References

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  1. ↑ X1 (コンピュータ), Japanese Wikipedia—link(accessed 2026-10-21) X1F section: Model 10 (CZ-811C) with built-in data recorder; Model 20 (CZ-812C) with one 5¼-inch 2D drive and an external FDD interface; IPL reset added beside the NMI reset. Basic specification: separate keyboards connect with a 3-pole 3.5 mm plug.
  2. ↑ 2.0 2.1 Rear panel photograph, File:Sharp X1F Model 10 rear panel.jpg (AKIBA PC Hotline!): the mains lead leaves the panel beside the marking AC 100V, below the POWER switch; the KEY BOARD jack is at the right-hand end.
  3. ↑ Front panel photograph by Jun Sasaki for the AKIBA PC Hotline! article (photo 4 of the article): indicators labelled TIMER, READ, REW, POWER, WRITE and FF to the right of a three-digit tape counter with its reset button.
  4. ↑ 4.0 4.1 4.2 X1シリーズで初となる5インチFDDを搭載した「X1F」– 佐々木 潤 (Jun Sasaki), AKIBA PC Hotline! (Impress), 2018-03-27—link(accessed 2026-10-21) Rear panel from the left: power switch, RGB, TV control, printer port, audio output, joystick ports, keyboard; expansion I/O slots above; a keyboard jack also on the left side of the front. Inside, the main board is smaller than on the first X1, and taking the case off is enough to check the condition of the cassette deck belts.
  5. ↑ Interior photograph, File:Sharp X1F Model 10 interior.jpg (AKIBA PC Hotline!), taken from above with the front of the machine at the bottom.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 CZ-8RL1カセットデッキの修理メモ, X1 Center—link(accessed 2026-10-21) Repair notes for the CZ-8RL1 data recorder: wear gloves or wash hands first, since hand grease speeds the ageing of rubber belts and marks steel parts; clean steel only with brush and vacuum, wipe resin parts with a damp tissue; one motor turns constantly and solenoids switch pulleys and cams, hence "electromagnetic mechanism"; belts are the loading belt, the fast forward/rewind and play reel belt and the tape counter belt; the tape counter carries the tape end sensor, so if it stops turning, play, fast forward and rewind stop almost at once; a sticky fast-forward gear was cleaned with alcohol and lubricated with dry PTFE; solvent-based oils, silicone and sprays can attack plastic gears and rubber and make clutches slip; the play-feed rubber ring looks like the CZ-800C's but is a different thickness, so the same substitute does not fit. Measured parts: loading belt 100 mm folded × 4.5 mm; FF/REW belt 70 mm folded × 1.2 mm square; play-feed ring 10.5 mm inside, 16 mm outside, 2.0 mm thick; counter belt 90 mm folded × 0.8 mm square.
  7. ↑ 7.0 7.1 7.2 CZ-800Cカセットデッキの修理メモ, X1 Center—link(accessed 2026-10-21) Repair notes for the built-in deck of the first X1 (CZ-800C): rubber parts degrade with age, and some of the butyl-type rubber melts into a sticky mass; a melted loading belt stops the head from loading when PLAY is pressed; if the head loads and the deck stops at once, the computer has probably detected tape end because the play-feed rubber ring has cracked and the take-up spool is not turning; that ring can be reached from the front without stripping the machine; measured loading belt about 111 mm folded (stretched and broken), 0.5 mm thick, 4.0 mm wide; FF/REW square belt 68 mm folded × 1.2 mm; play/FF ring 10.5 mm inside, 16 mm outside, 2.5 mm thick, not interchangeable with the CZ-8RL1's; counter belt 86 mm folded × 0.9 mm; on the CZ-800C the main board has to come out to change the loading belt.
  8. ↑ 8.0 8.1 8.2 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-812CE and CZ-812CR (X1F Model 20): one 5¼-inch 2D drive plus room for one more; drive TEAC FD-55BV-23; add-on internal drives CZ-52FE and CZ-52FR; FD-55BV-23 step rate 6 ms, input terminator 1 kΩ, no head restore at power-on; X1F Model 20 internal drive cable can be replaced and the internal drive can be reached from the external connector, whose input pull-ups are 150 Ω.
  9. ↑ 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; the plug is a standard 3.5 mm mini plug and audio cable works; six screws on the underside of the keyboard; the cord's three-pin connector unplugs from the board and a metal pin holds the strain relief.
  10. ↑ X1 (コンピュータ), Japanese Wikipedia—link(accessed 2026-10-21) X1F: the keyboard became the thin type of the X1turbo, with small design differences.
  11. ↑ キーボードコネクタの半田剥離, X1 Center—link(accessed 2026-10-21) Keyboard connectors that make poor contact or stop working are one of the most frequent faults on the X1, turbo and Z series; contact cleaner cures light oxidation, but a keyboard that works only with the plug under tension in one direction usually means a cracked joint on the connector board, cured by reflowing it.
  12. ↑ 搭載チップセット, X1 Center—link(accessed 2026-10-21) CZ-811CE and CZ-812C: backup battery "none" (the first X1 and the X1D have a 2.4 V 30 mAh cell).


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