Sharp X68000 Capacitor Replacement Guide
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The Sharp X68000 (CZ-600C) has electrolytic capacitors in the power supply, on the two boards in the right-hand tower, on the board in the base, on the 1 MB memory board, in each floppy drive and in the keyboard. Sharp's service manual for this model has not been republished. The lists below are those of Poe, a Japanese repairer who recapped a CZ-600C and published every position with its value, voltage and series.[1] They are a secondary source, read from one machine, so check each part on your own board before ordering.
The lists give positions and values but do not say what each capacitor does. The power supply of the CZ-600C was used in no later model, and none of these lists applies to the ACE or later machines.[2]
Warning: the power supply works from 100 V mains and its primary capacitor C706 is rated 200 V. Unplug the machine and let the supply discharge before you open it. Fram, repairing the supply of an X68000 XVI-HD, warns that more than 100 V DC remains on the primary side after the plug is pulled.[3]
Power supply
[edit | edit source]The supply is the metal-cased unit in the drive tower, labelled UADP-0047CEZZ on the machine Dave Jones took apart.[4]
| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C706 | 470 µF | 200 V | GM(M) | 470 µF 250 V Nichicon GX(M) |
| C709 | 22 µF | 25 V | VX(M) | 22 µF 50 V KMG |
| C710 | 4.7 µF | 50 V | VX(M) | 4.7 µF 50 V KMG |
| C714 | 4700 µF | 10 V | PF(M) | 4700 µF 10 V KY |
| C715 | 3300 µF | 10 V | PF(M) | 3300 µF 10 V KY |
| C716 | 3300 µF | 10 V | PF(M) | 3300 µF 10 V KY |
| C717 | 2.2 µF | 50 V | BP(M) | 2.2 µF 50 V KME |
| C718 | 2200 µF | 6.3 V | VX(M) | 2200 µF 6.3 V KMG |
| C719 | 680 µF | 16 V | PF(M) | 680 µF 16 V KY |
| C720 | 47 µF | 6.3 V | VX(M) | 47 µF 6.3 V KMG |
| C721 | 2700 µF | 35 V | PF(M) | 2700 µF 35 V KY |
| C724 | 470 µF | 16 V | PF(M) | 470 µF 16 V KY |
| C725 | 470 µF | 35 V | PF(M) | 470 µF 35 V KY |
| C726 | 22 µF | 25 V | VX(M) | 22 µF 50 V KMG |
| C728 | 47 µF | 10 V | BP(M) 85 °C H8718 | 47 µF 50 V KME |
[1] Poe kept the original capacitance on every position and raised the voltage rating on C706, C709, C726 and C728. C714, C715, C716 and C718 are the large low-voltage parts, from 2200 µF to 4700 µF.[1]
Right-hand tower boards
[edit | edit source]Poe lists the two boards in the right-hand tower as the upper and the lower board. The teardown photographs show C2, C3, C21, C22, C26, C28 and C36 from the lower list in the sound and video output section of the main board K5023DE, and C45 from the upper list on the video board K5024DE.[5][6]
Main board K5023DE
[edit | edit source]| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C1 | 470 µF | 10 V | SME | 470 µF 16 V KMG |
| C2 | 470 µF | 10 V | SME | 470 µF 16 V KMG |
| C3 | 470 µF | 10 V | SME | 470 µF 16 V KMG |
| C7 | 100 µF | 16 V | VX(M) | 100 µF 16 V KMG |
| C9 | 100 µF | 16 V | VX(M) | 100 µF 16 V KMG |
| C20 | 470 µF | 16 V | SME | 470 µF 16 V KMG |
| C21 | 2.2 µF | 50 V | SM | 2.2 µF 50 V KMG |
| C22 | 100 µF | 16 V | VX(M) | 100 µF 16 V KMG |
| C26 | 100 µF | 16 V | VX(M) | 100 µF 16 V KMG |
| C28 | 100 µF | 16 V | VX(M) | 100 µF 16 V KMG |
| C30 | 100 µF | 16 V | VX(M) | 100 µF 16 V KMG |
| C33 | 2.2 µF | 50 V | SM | 2.2 µF 50 V KMG |
| C34 | 2.2 µF | 50 V | SM | 2.2 µF 50 V KMG |
| C36 | 2200 µF | 6.3 V | SME | 2200 µF 16 V KMG |
| C47 | 22 µF | 16 V | SE(M) | 22 µF 50 V KMG |
| C48 | 1 µF | 50 V | SE(M) | 1 µF 50 V KMG |
| C50 | 1 µF | 50 V | SE(M) | 1 µF 50 V KMG |
| C52 | 0.47 µF | 50 V | Nichicon 85 °C | 0.47 µF 50 V UTEW |
| C53 | 1 µF | 50 V | SE(M) | 1 µF 50 V KMG |
| C139 | 100 µF | 10 V | VX(M) | 100 µF 16 V KMG |
[1] C36 (2200 µF 6.3 V) has the largest value on the board. Poe replaced it with a 16 V part.[1]
Video board K5024DE
[edit | edit source]| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C37 | 7 µF (as printed; see below) | 16 V | SME | 47 µF 25 V KMG |
| C45 | 100 µF | 16 V | SME | 100 µF 16 V KMG |
[1] Poe's list gives C37 as 7 µF and the replacement he fitted as 47 µF 25 V. No standard electrolytic is 7 µF, so read the value printed on your own C37 before ordering.[1]
Board in the base
[edit | edit source]The board under the two towers carries 33 electrolytics in Poe's list. The commonest are 4.7 µF 50 V (ten positions), 47 µF 16 V and 100 µF 10 V (five each).[1]
| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C8 | 47 µF | 16 V | SME | 47 µF 25 V KMG |
| C9 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C15 | 47 µF | 16 V | SME | 47 µF 25 V KMG |
| C16 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C17 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C18 | 1 µF | 50 V | SE(M) | 1 µF 50 V KMG |
| C20 | 1 µF | 50 V | SE(M) | 1 µF 50 V KMG |
| C21 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C22 | 100 µF | 10 V | SME | 100 µF 16 V KMG |
| C23 | 100 µF | 10 V | SME | 100 µF 16 V KMG |
| C24 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C25 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C26 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C27 | 10 µF | 16 V | SE(M) | 10 µF 50 V KMG |
| C28 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C29 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C30 | 4.7 µF | 50 V | SE(M) | 4.7 µF 50 V KMG |
| C33 | 0.47 µF | 50 V | SE(M) | 0.47 µF 50 V UTEW |
| C34 | 0.47 µF | 50 V | SE(M) | 0.47 µF 50 V UTEW |
| C35 | 0.47 µF | 50 V | SE(M) | 0.47 µF 50 V UTEW |
| C41 | 47 µF | 16 V | SME | 47 µF 25 V KMG |
| C42 | 47 µF | 16 V | SME | 47 µF 25 V KMG |
| C43 | 47 µF | 16 V | SME | 47 µF 25 V KMG |
| C45 | 10 µF | 16 V | SE(M) | 10 µF 50 V KMG |
| C46 | 10 µF | 16 V | SE(M) | 10 µF 50 V KMG |
| C49 | 100 µF | 10 V | SME | 100 µF 16 V KMG |
| C50 | 100 µF | 10 V | SME | 100 µF 16 V KMG |
| C53 | 100 µF | 16 V | SME | 100 µF 16 V KMG |
| C54 | 100 µF | 10 V | SME | 100 µF 16 V KMG |
| C112 | 470 µF | 10 V | SME | 470 µF 16 V KMG |
| C113 | 330 µF | 10 V | SME | 330 µF 16 V KMG |
| C114 | 330 µF | 16 V | VX(M) | 330 µF 16 V KMG |
| C115 | 100 µF | 16 V | SME | 100 µF 16 V KMG |
Memory board CZ-6BE1
[edit | edit source]| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C2 | 100 µF | 16 V | SME | 100 µF 16 V KMG |
[1] Poe found C2 the hardest capacitor in the machine to remove, because its holes are narrow and oxidised. Cut the capacitor off, then take the legs out one at a time with desoldering braid. If a hole stays blocked, open it carefully with a pin vice.[1]
Floppy drives
[edit | edit source]Each K-61432-71 drive has the seven positions below, which Poe lists with designators, and four smaller parts without designators: two 22 µF 16 V, one 10 µF 16 V and one 1 µF 50 V bipolar. Poe fitted the bipolar part as a 5 × 11 mm capacitor laid on its side.[1]
| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C13 | 100 µF | 16 V | Nichicon N728 85 °C low-profile | 100 µF 16 V KMG |
| C18 | 100 µF | 16 V | Nichicon N728 85 °C low-profile | 100 µF 16 V KMG |
| C20 | 100 µF | 16 V | Nichicon N728 85 °C low-profile | 100 µF 16 V KMG |
| C22 | 100 µF | 16 V | Nichicon N728 85 °C low-profile | 100 µF 16 V KMG |
| C10 | 10 µF | 16 V | Nichicon N742 85 °C 4×5 | 10 µF 16 V KMG |
| C24 | 10 µF | 16 V | Nichicon N732 85 °C 4×5 | 10 µF 16 V KMG |
| C26 | 10 µF | 16 V | Nichicon N744 85 °C 4×5 | 10 µF 16 V KMG |
[1] The fit varies with the drive's version number. On versions 03, 04 and 07 of the K-61432-71, Poe lists C13, C18, C20 and C22 as 100 µF 6 V, and the parts in the centre of the drive as five 22 µF 16 V, one 10 µF 16 V and two 1 µF 50 V, one of them bipolar.[7] The parts in the centre sit on the board with the spindle motor driver and can only be reached by dismantling the drive. Poe found them leaking, and the driver's pins corroded.[7] Do not take the spindle motor or the stepping motor off just to reach the capacitors: the head position depends on their alignment.[7]
Keyboard
[edit | edit source]| Ref | Capacitance | Voltage | Original series | Poe fitted |
|---|---|---|---|---|
| C3 | 2.2 µF | 50 V | CE-US | 2.2 µF 50 V KY |
| C8 | 100 µF | 10 V | CE-US | 100 µF 10 V KY |
Replacement procedure
[edit | edit source]- Unplug the machine and leave the supply to discharge. Measure across C706 before touching the supply board.
- Photograph every board and mark the polarity of each electrolytic before removing it.
- Start with the power supply. Poe soaks a supply board in isopropyl alcohol for about five minutes, just deep enough to cover the component legs, so that leaked electrolyte comes away more easily, then brushes the residue off both sides.[8]
- Look for burnt patches and darkened resistors near any leak. Leaked electrolyte conducts, and on later X68000 supplies it has destroyed transistors and blown the fuse.[3][2] Replace damaged parts as well as the capacitors.
- Replace the capacitors on the main board, the video board, the base board and the memory board.
- For each floppy drive, replace the capacitors on the drive board first. Take the drive apart for the centre parts only if you are prepared to check the head alignment afterwards.[7]
- Fit parts of the same capacitance and at least the same voltage.
- Check the outputs of the supply with a meter before refitting the boards.
Related pages
[edit | edit source]- Sharp X68000
- Sharp X68000 General Maintenance
- Sharp X68000 Troubleshooting Guide
- Capacitor Failure Symptoms
- Floppy Drive Repair
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 SHARP X68000 修理– Poe—link(accessed 2026-10-21) Capacitor lists for a CZ-600C, with original values, series and the replacements fitted: 1 MB RAM board CZ-6BE1 (C2), right tower upper board (C37, C45), right tower lower board (20 parts), board under the towers (33 parts), floppy drive (per drive), keyboard (C3, C8) and power supply (C706 to C728); C2 on the RAM board has narrow, oxidised holes and is best cut off and its legs removed with desoldering braid; spares list for the supply: 250 V 4 A glass fuse (5.2 × 20 mm) with PCB fuse clips, 3.96 mm VH connector contacts, X-FAN RDL6025S 12 V fan.
- ↑ 2.0 2.1 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) Table of power supply types by model: the CZ-600C supply was used only in the first model; the ACE used SH2, the ACE-HD SH3, the EXPERT to X68030 SH4. SH5 repair in which transistors Q31 and Q32 had failed short and the fuse had blown.
- ↑ 3.0 3.1 X68kXVI HDの電源リペア– Fram, 2015-05-23—link(accessed 2026-10-21) Warning that over 100 V DC remains on the primary side of the X68000 supply after unplugging; leaking "Long Life" capacitors whose electrolyte ran onto the board and down the power cable to the base board; burnt board area where the electrolyte had shorted a zener diode, R33/R34 and a transistor; exploded power transistor and blown fuse; all capacitors and the damaged parts replaced; the supply switches its outputs on when its own main switch is turned on, so it can be tested on its own.
- ↑ Sharp X68000 Personal Computer Teardown (17267174853)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph of the drive tower of a CZ-600C with the power supply labelled UADP-0047CEZZ (ZSSE640J).
- ↑ Sharp X68000 Personal Computer Teardown (17884657232)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Main board K5023DE, sound and video output area: electrolytics C2, C3, C18, C21, C22, C26, C28 and C36 beside IC16 (M51387P).
- ↑ Sharp X68000 Personal Computer Teardown (17699842898)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Board K5024DE with the electrolytic C45 near IC37 (RESERVE); most of the other capacitors visible on this board are tantalum or ceramic.
- ↑ 7.0 7.1 7.2 7.3 SHARP X68000 FDD K61432-71 K61432-72 K-61435-72 修理– Poe, 2020-02-23—link(accessed 2026-10-21) Capacitor lists for K-61432-71 version 09 (C13, C18, C20, C22 100 µF 16 V; C10, C24, C26 10 µF 16 V; 22 µF, 10 µF and 1 µF bipolar parts at the centre) and for versions 03, 04 and 07 (C13, C18, C20, C22 100 µF 6 V; five 22 µF, one 10 µF, two 1 µF); capacitors at the centre of the drive, reachable only after dismantling it, and on the spindle motor driver board found leaking, with the driver's pins sometimes corroded; capacitor fit differs between drive versions; the spindle and stepping motors should not be removed just to change capacitors, because the head position depends on their alignment.
- ↑ SHARP X68000 SUPER / SUPER-HD CZ-604C CZ-623C 修理備忘録– Poe, 2020-03-01—link(accessed 2026-10-21) Power supply cleaning before recapping: board soaked in IPA for about five minutes up to the component legs, then leaked electrolyte brushed off both sides with a toothbrush and cotton buds.
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