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Sharp PC-1245 Capacitor Replacement Guide

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Sharp PC-1250 and PC-1251 main board capacitor positions (service manual)
Capacitor positions on the PC-1250/PC-1251 main board, from Sharp's service manual for those models. This is not a PC-1245 board; no PC-1245 board drawing is available.

Capacitors in the Sharp PC-1245. No capacitor values have been published for the PC-1245: Sharp's instruction manual does not describe the circuit, and the Sharp Pocket Computers archive, which holds service manuals for the PC-1246/1247, PC-1248 and PC-1250/1251, has none for the PC-1245.[1]

The cells are a documented risk to the board: Sharp warns that a dead cell left in the computer can leak and damage it.[2] See Sharp PC-1245 General Maintenance and Battery Explosion, Capacitor or Corrosion Damage.

What the PC-1250/1251 board has

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The PC-1245 and PC-1251 share a 24 KB ROM, the CR-2032 cell pair, a 0.03 W power consumption and the same 135 × 70 × 9.5 mm case dimensions in Sharp's specifications.[3][4] Sharp's PC-1250/1251 service manual lists only two polarised capacitors on that board.[5]

Polarised capacitors on the PC-1250/PC-1251 board (not the PC-1245)[5]
Value Rating Circuit
3.3 µF 10 V Across the VGG supply from the cells
1 µF 6.3 V LCD drive voltage VDIS

These are values from a different model, given for comparison. A PC-1245 may use the same values, different values or a different layout. Do not order parts until you have read your own board. Details of the PC-1250/1251 parts are on the Sharp PC-1251 Capacitor Replacement Guide.

Recording your own board

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  1. Take out the cells and undock the computer from the CE-125.
  2. Remove the back cover screws and open the case carefully, photographing each stage. There is no published disassembly procedure for the PC-1245.
  3. Photograph both sides of the main board in good light.
  4. Look for polarised capacitors near the cell terminals and near the contrast control on the right-hand side, which are where the PC-1250/1251 board has its two.[5][6] Read the value, voltage and polarity printed on each.
  5. Note any corrosion, especially near the cells.
  6. Record what you find against the board marking, so that PC-1245 boards can be compared.

Replacement

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  1. Use an anti-static strap; the processor is CMOS.[3]
  2. Note the polarity before removing a part.
  3. Replace like with like: the same capacitance, a voltage rating at least as high, and the same package size.
  4. Refit the cells and press RESET; the prompt > should appear.[2]

Checks afterwards

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After the work (Sharp PC-1245 instruction manual)
Check Expected
Switch on and press RESET after fitting cells The prompt > appears[2]
Contrast control A clear display can be set[6]
Keys Every key responds; ON restarts the machine after auto power-off[7]
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References

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  1. ↑ Sharp Pocket Computers, Printers, Cables, Level Converters & Accessories, sharppocketcomputers.com—link(accessed 2026-10-21) The PC-1245 row lists an operation manual only.
  2. ↑ 2.0 2.1 2.2 Sharp, PC-1245 instruction manual, chapter 2, "Cell replacement", printed pages 14 to 16 (PDF pages 16 to 18).
  3. ↑ 3.0 3.1 Sharp, PC-1245 instruction manual, appendix G "Specifications", printed page 157 (PDF page 159): 8-bit CMOS CPU; 24 KB ROM; CR-2032 cells; 0.03 W; 135 × 70 × 9.5 mm. Hosted as File:Sharp PC-1245 Instruction Manual.pdf.
  4. ↑ Sharp, PC-1251 instruction manual, appendix G "Specifications", printed page 173 (PDF page 175). Hosted as File:Sharp PC-1251 Instruction Manual.pdf.
  5. ↑ 5.0 5.1 5.2 Sharp Corporation, Service Manual, Model PC-1251, PC-1250, December 1982, circuit diagram (PDF page 12), parts position (PDF page 13) and parts list (PDF page 18): 3.3 µF 10 V and 1 µF 6.3 V. Hosted as File:Sharp PC-1251 Service Manual.pdf.
  6. ↑ 6.0 6.1 Sharp, PC-1245 instruction manual, chapter 2, "Contrast control", printed page 13 (PDF page 15), and "Installing the cells", printed page 14 (PDF page 16): the contrast control is on the right of the computer.
  7. ↑ Sharp, PC-1245 instruction manual, chapter 3, printed page 17 (PDF page 19).


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