Sharp X68000 EXPERT
 | |
| An X68000 EXPERT (right) beside an X68030 (left), with an X68000 keyboard in front (photo: Manupkp, CC BY-SA 4.0) | |
| Specifications | |
|---|---|
| Manufacturer | Sharp |
| Type | Personal computer |
| Released | March 1989 (EXPERT); March 1990 (EXPERT II)[1] |
| Intro price | ¥356,000 (EXPERT); ¥338,000 (EXPERT II)[2] |
| CPU | Hitachi HD68HC000 at 10 MHz[2] |
| Memory | 2 MB[1] |
| Storage | Two 5.25-inch 2HD floppy drives; 40 MB SASI hard disk in the -HD models[1][2] |
| Display | — |
| Sound | — |
| Power | 100 V AC[2] |
| OS / Firmware | — |
| Successor | Sharp X68000 SUPER |
| Model no. | CZ-602C, CZ-612C (EXPERT, EXPERT-HD); CZ-603C, CZ-613C (EXPERT II, EXPERT II-HD) |
The Sharp X68000 EXPERT (CZ-602C) and EXPERT II (CZ-603C) are twin-tower models of the Sharp X68000 sold in Japan from March 1989 and March 1990, each also offered with a 40 MB hard disk as the EXPERT-HD (CZ-612C) and EXPERT II-HD (CZ-613C).[1][2] The EXPERT was the first X68000 with 2 MB of memory as standard; the EXPERT II added the gold X68000 emblem, an improved BIOS and the SX-WINDOW graphical environment.[2]
Both use the power supply that owners call the SH4, the same board as the Sharp X68000 SUPER, Sharp X68000 XVI and Sharp X68030.[3][4] Sharp's circuit diagram of that supply is in the Sharp X68000 XVI Service Manual. The EXPERT and the EXPERT II have different main, base and analogue boards from each other and from the later models.[4] Poe, a Japanese repairer, has written up EXPERT and EXPERT II repairs covering the floppy drives, the memory settings and the reset button.[4]
History
[edit | edit source]The EXPERT and EXPERT-HD went on sale in March 1989 at ¥356,000 and ¥466,000, in grey or black. The EXPERT II and EXPERT II-HD followed in March 1990 at ¥338,000 and ¥448,000; the EXPERT II-HD set won a Good Design Award that year.[1][2] The Sharp X68000 SUPER replaced them, with a SCSI port in place of the older hard disk interface.[1][2]
Hardware
[edit | edit source]Boards
[edit | edit source]| Board | EXPERT (CZ-602C, CZ-612C) | EXPERT II (CZ-603C) |
|---|---|---|
| Power supply | SH4 | SH4 |
| Main board | K6247DE | K6708DE |
| Base board | K6248DE | K6709DE |
| Analogue board | K6249DE | K6710DE |
| Expansion slot board | K6250DE | K6711DE |
| External interface board | K6251DE | K6712DE (upper), K6713FD (lower, floppy) |
| Lamp boards | K6253DE (POWER), K6254DE and K6255DE (above and below the drives) | K6714DE (POWER), K6715DE and K6716DE |
Power supply
[edit | edit source]The SH4 runs from 100 V mains. Sharp's XVI diagram of the board shows a 125 V 4 A fuse, +12 V, −12 V and +5 V outputs, and a separate +5 V standby rail from a second, smaller converter.[5] Like the other tower models, the EXPERT has a main switch on the rear as well as the front switch.[2]
Floppy drives
[edit | edit source]The two 5.25-inch drives are the K61432-72 type used from the ACE to the X68030. Poe found the drive in an EXPERT with the lubricant on its head motor shaft set solid, so that the head would not move; he cleaned it, re-greased it and replaced all its capacitors. On that drive, version 05, the capacitors at the spindle motor are easy to reach.[4][6]
Known problems
[edit | edit source]- Leaking power supply capacitors, as on every SH4.[3][7] See the Sharp X68000 EXPERT Capacitor Replacement Guide.
- Floppy drive heads seized by hardened lubricant.[4]
- Reset buttons that respond poorly; Poe replaces them with an Alps tactile switch.[4]
Repair guides
[edit | edit source]- Sharp X68000 EXPERT General Maintenance
- Sharp X68000 EXPERT Troubleshooting Guide
- Sharp X68000 EXPERT Capacitor Replacement Guide
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 X68000, IPSJ Computer Museum, Information Processing Society of Japan—link(accessed 2026-10-21) Series table: X68000 EXPERT, CZ-602C, March 1989, 2 MB; EXPERT-HD, CZ-612C, 40 MB hard disk; EXPERT II, CZ-603C, March 1990, 2 MB; EXPERT II-HD, CZ-613C, 40 MB; the hard disk interface column reads SASI for the earlier models and SCSI from the SUPER-HD (June 1990).
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 X68000, Wikipedia (Japanese)—link(accessed 2026-10-21) Model table: EXPERT CZ-602C ¥356,000 and EXPERT-HD CZ-612C ¥466,000 (40 MB), March 1989, grey or black (-GY/-BK), tower, 2 MB, the first model with 2 MB as standard; EXPERT II CZ-603C ¥338,000 and EXPERT II-HD CZ-613C ¥448,000 (40 MB), March 1990, grey or black, tower, 2 MB, gold X68000 emblem, improved BIOS, SX-WINDOW supplied, and the CZ-613C set won a 1990 Good Design Award. The original model, ACE, EXPERT and SUPER use Hitachi's HD68HC000 at 10 MHz. The hard disk port became SCSI from the SUPER. The tower models have a main power switch on the rear as well as the front switch.
- ↑ 3.0 3.1 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) Supply by model, quoted from Poe: EXPERT and EXPERT-HD (CZ-602C, CZ-612C) and EXPERT II and EXPERT II-HD (CZ-603C, CZ-613C) use the SH4, as do the SUPER, XVI and X68030. Repairs usually start with replacing leaking electrolytics.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 X68000 EXPERT CZ-602C CZ-612C / EXPERT II CZ-603C CZ-613C / FDDユニット K61432-72 修理備忘録– Poe—link(accessed 2026-10-21) EXPERT (CZ-602C, CZ-612C) parts: power supply SH4, main board K6247DE, analogue board K6249DE, base board K6248DE, expansion slot board K6250DE, external interface board K6251DE, lamp boards K6253DE (right tower, POWER), K6254DE and K6255DE (left tower, above and below the drives). EXPERT II (CZ-603C): SH4, main K6708DE, analogue K6710DE, base K6709DE (part numbers differ from the EXPERT), expansion slot K6711DE with four 47 µF 10 V capacitors, external interface upper K6712DE and lower (floppy) K6713FD, lamps K6714DE to K6716DE. Repair of an EXPERT's K61432-72 drive (version 05): the lubricant on the head motor shaft had hardened and the head did not move; cleaned, re-greased, all capacitors replaced; the spindle motor capacitors of version 05 are easy to change. SRAM initialisation with DB.X. Poorly responding reset buttons replaced with Alps SKHCBFA010 tactile switches (12 × 12 × 4.3 mm, RS stock number 119-2015).
- ↑ Sharp, service manual CZ-134 for the X68000 XVI (File:Sharp X68000 XVI Service Manual.pdf), 22, power supply basic wiring diagram, printed pages 97 and 98 (PDF page 85): SH4 board UADP-0069CEZZ; fuse F1 125 V 4 A; +12 V, −12 V and +5 V outputs; +5 V standby (VCC2) from IC31 and transformer T2. See Sharp X68000 XVI Service Manual.
- ↑ SHARP X68000 FDD K61432-71 K61432-72 K-61435-72 修理– Poe, 2020-02-23—link(accessed 2026-10-21) K-61432-72 drive for the ACE to the X68030; capacitor lists for versions 03, 04 and 07; do not remove the spindle or stepping motor just to change capacitors.
- ↑ X68kXVI HDの電源リペア– Fram, 2015-05-23—link(accessed 2026-10-21) SH4 supply from an XVI-HD: leaking capacitors, electrolyte shorted the zener diode, R33/R34 and a transistor; a power transistor burst and the fuse blew.