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Sharp MZ-80K2 Capacitor Replacement Guide

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Sharp MZ-80K power supply circuit (service manual)
Power supply of the European MZ-80K, from Sharp's service manual. The MZ-80K2's 100 V supply is a different unit and has no published schematic.

Sharp did not include the Sharp MZ-80K2 in its MZ-80K service manual, and SharpMZ.net, which hosts that manual, lists only a Japanese owner's manual for the K2.[1][2] No capacitor values have been published for the K2 itself. The K2 is the factory-assembled version of the MZ-80K and runs from 100 V in Japan.[3] The values Sharp gives for the European MZ-80K are in the Sharp MZ-80K Capacitor Replacement Guide. Use them to compare against the K2's board, and order parts from the markings on the K2's own capacitors.

What the MZ-80K list covers

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Sharp's MZ-80K parts list gives every electrolytic and tantalum capacitor on four units:[2]

  • The power supply: the reservoirs and output capacitors, and four 10 µF 35 V tantalums (C401, C501, C502 and C509). This is the European 220 V and 240 V supply, not the K2's 100 V unit.
  • The CPU board: aluminium electrolytics from 1 µF to 220 µF, the three 100 µF 25 V capacitors C36, C37 and C38 at the power input, and two tantalums, C39 (33 µF 10 V) and C41 (10 µF 35 V).
  • The monitor board: twenty aluminium electrolytics, including C2003 (10 µF 160 V) and C2048 (220 µF 100 V), and one tantalum, C2009 (1 µF 35 V).
  • The cassette recorder: C3001, C3003 and C3009.

If the K2's CPU board, monitor board or cassette board carries the same assembly numbers and designators as the MZ-80K's, the MZ-80K values are a sound starting point for those boards. Check each part on the board before ordering.

The tantalum capacitors

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On the MZ-80K, the power supply's tantalum capacitors are the parts owners report failing, shorted, with smoke from the supply or the mains fuse blowing.[4] Adam Wilson replaced every tantalum and aluminium capacitor on his MZ-80K's CPU board.[5] Check the K2's supply and CPU board for tantalums first.

Recording your own board

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  1. Unplug the machine and open it. The MZ-80K procedure is in Sharp MZ-80K General Maintenance#Opening the case.
  2. Photograph each board before removing anything.
  3. For each electrolytic and tantalum capacitor, write down the designator, the capacitance, the voltage, the type and the polarity mark.
  4. Compare the list with the Sharp MZ-80K Capacitor Replacement Guide and note any difference, especially on the power supply.
  5. Replace like for like: the same capacitance and at least the same voltage. On a negative rail (−5 V on the MZ-80K) the positive lead goes to ground.[6]
  6. After replacing the supply capacitors, measure the outputs at the CPU board before refitting the other boards.
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References

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  1. ↑ MZ-80K Manuals, SharpMZ.net—link(accessed 2026-10-21) Lists the "Japanese Manual MZ-80K2" and the MZ-80K Service Manual.
  2. ↑ 2.0 2.1 Sharp Corporation, Service Manual, Personal Computer MZ-80K (File:Sharp MZ-80K Service Manual.pdf): covers the MZ-80K with the 220 V power supply DBOXD0004PAZZ and the UK 240 V unit DBOXD0005PAZZ; replacement parts list, printed pages 43 to 47. Hosted with a description at Sharp MZ-80K Service Manual.
  3. ↑ MZ-80, Wikipedia (Japanese)—link(accessed 2026-10-21) MZ-80K2 (1980): assembled, 32 KB RAM, nearly equivalent to the MZ-80K in software; MZ-80K series in Japan: AC 100 V ±10 % 50/60 Hz.
  4. ↑ Sharp MZ-80K Power Supply repair– xAD / nIGHTFALL, nIGHTFALL Blog, 2013-01-13—link(accessed 2026-10-21) Four short-circuited tantalum capacitors in an MZ-80K power supply replaced with electrolytic capacitors; owners report smoke and the 500 mA fuse F101 blowing.
  5. ↑ 1980 Sharp MZ-80K Repair & Restoration– Adam Wilson, Adam's Vintage Computer Restorations, 2026-01-31—link(accessed 2026-10-21) Tantalum and aluminium electrolytic capacitors on the MZ-80K mainboard replaced; four 10 µF tantalums in the power supply.
  6. ↑ Sharp, MZ-80K service manual (File:Sharp MZ-80K Service Manual.pdf), power supply wiring diagram, printed page 37 (PDF page 39), and CPU board circuit diagram (10), printed page 35 (PDF page 37): C201, C202 and C38 on −5 V with the positive side to ground.


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