Sharp X68000 ACE Capacitor Replacement Guide
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The Sharp X68000 ACE (CZ-601C) and ACE-HD (CZ-611C) have their own power supplies, the SH2 and the SH3, and their own boards; they do not share the SH4 of the later tower models.[1][2] No complete capacitor list and no Sharp service manual for them has been published. What is known is set out below; for every other position, read the value, voltage and polarity from the part before removing it.
Warning: the supplies run from 100 V mains. Treat the SH2 and SH3 as you would the SH4, whose primary side holds more than 100 V DC after the plug is pulled: unplug the machine, wait, and measure across C9 (rated 180 V on the SH2) before touching the primary side.[3][4]
Power supply (SH2 and SH3)
[edit | edit source]| Ref | Value | Voltage | Position |
|---|---|---|---|
| C9 | 390 µF | 180 V | Primary reservoir |
| C40 | 3900 µF | 10 V | +5 V output |
| C41 | 3900 µF | 10 V | +5 V output |
[3] Poe's note on these reads "the capacitance differs but it can be used" and says no more; the SH4 has 470 µF and 5600 µF in those positions.[3][5] He also records that SH2 boards exist in yellow paper-epoxy and green glass-epoxy versions, and that no replacement for the main connector is available, so take care with it.[3] The positions above are given by analogy with the SH4, where C9 is the primary reservoir and C40 and C41 smooth the +5 V output; check them on your board.[5]
Poe photographed electrolyte leaking on an SH2 board.[2] No list has been published for the SH3; kunichiko's in-circuit resistance readings for an ACE's SH3 help to find damaged parts after a recap.[1] The general SH4 procedure on the XVI capacitor guide (discharge, photograph, clean, replace one part at a time, test on the bench) applies, but the values and positions do not.
Control board (K5710DE)
[edit | edit source]The nickel-cadmium backup cell sits on this board in the base, and on Poe's ACE it had leaked.[2]
- Remove the cell first and see how far the electrolyte has spread.[2]
- Check the tracks around it for breaks.[2]
- Inspect the nearby parts. Poe found the cell's metal terminals corroded almost through and pins 1 to 4 of the MC68901P (the MFP chip) rusted, and replaced that chip.[2]
- Replace the capacitors in the leak area, reading their values from the parts. Poe removed the board's capacitors along with the cell.[2]
Cleaning after a cell leak is covered in Battery Explosion, Capacitor or Corrosion Damage.
Main and analogue boards (K5709DE, K5711DE)
[edit | edit source]No capacitor list has been published for either board.[2] Record each part before removing it.
Floppy drives
[edit | edit source]The ACE's drives are the K61432-72 type. Poe lists the capacitors of versions 03, 04 and 07: C13, C18, C20 and C22 (100 µF, Nichicon N728 low-profile), C10, C24 and C26 (10 µF 16 V), five unnumbered 22 µF 16 V, one 10 µF 16 V, one 1 µF 50 V and one 1 µF 50 V bipolar. His version table gives the 100 µF parts as 6 V and his stock list as 16 V, so read the cans first.[6] The ACE-HD drive he serviced was version 02, on which the spindle motor is easy to remove.[2] On other versions, leave the spindle and stepping motors in place.[6]
Keyboard
[edit | edit source]No capacitor list has been published for the ACE keyboard. The original X68000 keyboard has C3 (2.2 µF 50 V) and C8 (100 µF 10 V).[3] Check your board before ordering.
Related pages
[edit | edit source]- Sharp X68000 ACE
- Sharp X68000 ACE General Maintenance
- Sharp X68000 ACE Troubleshooting Guide
- Sharp X68000 Capacitor Replacement Guide
- Sharp X68000 XVI Capacitor Replacement Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 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) ACE (CZ-601C) SH2, ACE-HD (CZ-611C) SH3, later tower models SH4. In-circuit resistance readings measured from the solder side of an ACE's SH3, for comparison when a recapped supply still fails.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 X68000 ACE/ACE-HD CZ-601C CZ-611C / FDDユニット K61432-72 / 電源 SH2･SH3 修理– Poe, 2021-01-20—link(accessed 2026-10-21) Control board (base) K5710DE with the nickel-cadmium cell; main board K5709DE; analogue board K5711DE. Photographs of the SH2 supply board with leakage and the ACE-HD's SH3. Control board: remove the cell, check the extent of the leak and look for broken tracks; terminals corroded almost to breaking; contacts with green corrosion; after the cell and capacitors were removed, pins 1 to 4 of the Motorola MC68901P were rusted and the chip was replaced. ACE-HD drive K61432-72 version 02: spindle motor easy to remove; capacitors replaced and re-greased.
- ↑ 3.0 3.1 3.2 3.3 3.4 SHARP X68000 修理– Poe—link(accessed 2026-10-21) Power supply table, CZ-601C ACE, SH2: "C9 180 V 390 µF, C40/C41 10 V 3900 µF; the capacitance is different but it can be used"; yellow (paper-epoxy) and green (glass-epoxy) boards exist; no replacement main connector. CZ-611C ACE-HD: SH3. CZ-600C keyboard C3 2.2 µF 50 V, C8 100 µF 10 V.
- ↑ 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.
- ↑ 5.0 5.1 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): on the SH4, C9 470 µF 180 V is the primary reservoir after the bridge, and C40 and C41 5600 µF 10 V smooth the +5 V output after rectifier D27.
- ↑ 6.0 6.1 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 from the ACE onwards. Versions 03, 04 and 07: C13, C18, C20, C22 100 µF 6 V Nichicon N728 low-profile; C10, C24, C26 10 µF 16 V; five 22 µF 16 V, one 10 µF 16 V, one 1 µF 50 V, one 1 µF 50 V bipolar, unnumbered; stock list with the 100 µF parts at 16 V. Do not remove the spindle or stepping motor just to change capacitors.