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Sharp PC-1500 Capacitor Replacement Guide

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Sharp PC-1500 main board power section (service manual)
The two 10 V 220 µF capacitors on the PC-1500 main board, beside the 1SS98 and 1S1588 diodes and the pads of the Hi-MIC regulator module (Sharp service manual).

Capacitor replacement on the Sharp PC-1500. The PC-1500 has only four electrolytic capacitors, and Sharp's service manual identifies all four: two 10 V 220 µF on the VGG supply and two 50 V 1 µF in the power-on reset circuit.[1][2][3][4] The rest of the capacitors are small ceramics. The Sharp PC-1500A uses the same power supply circuit; see Sharp PC-1500A Capacitor Replacement Guide for its board.

Because the machine runs from four AA cells, the cells and their leakage do far more damage in practice than the capacitors. Deal with any battery corrosion first; see Sharp PC-1500 General Maintenance and Battery Explosion, Capacitor or Corrosion Damage.

Signs that the capacitors need attention

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  • Electrolyte residue, a bulging or split sleeve, or corrosion round either 220 µF capacitor or either 1 µF capacitor.
  • VGG low or unstable with good cells and a sound VBAT; Sharp specifies 4.7 V.[5]
  • The machine powers up into garbage or needs the all reset every time it is switched on, which points at the reset circuit.[3]
  • See Capacitor Failure Symptoms.

PC-1500 capacitor list

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Sharp's parts list identifies parts by code and description only, with no circuit designators, so the electrolytics below are described by position. The values, voltages and positions come from the key and power supply circuit (printed page 21), the main board drawing (printed page 23) and the main circuit diagram (printed page 24).[1][2][3][4]

PC-1500 electrolytic capacitors (Sharp service manual)
Qty Value Rating Sharp part code Circuit Position on the main board
2 220 µF 10 V RC-EZ227ACC1A Between VGG and ground at the output of the Hi-MIC regulator module Side by side next to the 1SS98 and two 1S1588 diodes, beside the row of module pads[2]
1 1 µF 50 V RC-EZ105ACC1H From VCC to the input of the TC50H001F Schmitt gate in the power-on reset circuit Beside the 2SC2412 transistor and the 5.6 kΩ resistor[2]
1 1 µF 50 V RC-EZ105ACC1H On the output network that drives the I/O port, CPU and µPD1990AC reset lines Beside the reset terminal[2]
Sharp PC-1500 reset circuit (service manual)
The power-on reset circuit from the PC-1500 main circuit diagram, with its two 50 V 1 µF capacitors (Sharp service manual).

The parts list also has these ceramic capacitors, which do not age the way electrolytics do and need no routine replacement:[4]

PC-1500 ceramic capacitors in Sharp's parts list[4]
Sharp part code Description
RC-CZ1021CCN1 0.1 µF
RC-CZ1023CCN1 100 pF
RC-CZ1041CCN1 15 pF
RC-CZ1042CCN1 30 pF

The key and power supply circuit shows two 0.1 µF capacitors from the battery lines to the frame ground.[1] The parts list gives no quantities, so count the parts on your own board before ordering.

Recording your own board

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  1. Take out the cells, remove any memory module and undock the computer from the CE-150.
  2. Open the case and photograph both sides of the main board before touching anything.
  3. Read the value, voltage and polarity of each electrolytic and compare them with the table. Note any board marking: the service manual's drawing is marked F2026C, and PC-1500.info reports boards marked F2075 and F2076 in an early machine.[2][6]
  4. Note any extra parts or wire links. PC-1500.info reports blue wire straps on some early machines, so not every link is a later repair.[6]

Replacement procedure

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  1. Wear an anti-static strap. The logic is CMOS.[7]
  2. Note the polarity of each capacitor before removing it. The board drawing marks the positive lead of each part.[2]
  3. Add fresh flux and a little fresh solder to each joint, then remove the capacitor one lead at a time and clear the holes with wick.
  4. Fit 220 µF capacitors rated 10 V or higher and 1 µF capacitors rated 50 V, as Sharp did.[4]
  5. Measure the height available under the case and match the size of the originals.
  6. Solder, trim and inspect for bridges, then clean off the flux with isopropyl alcohol.
  7. Handle the FPC gently while the boards are apart. It is soldered to the key board and crimped to the main board.[8]
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  • Two 220 µF electrolytics, 10 V or higher, 105 °C.
  • Two 1 µF electrolytics, 50 V, 105 °C.
  • Temperature-controlled soldering iron with a fine tip, solder wick, flux and leaded solder.
  • Digital multimeter.

See Recommended Tools for the general workshop kit.

Checks after replacement

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After the recap (targets from Sharp's service manual at 25 °C)[5][1]
Check Where Expected
VGG Hi-MIC module pin 13 4.7 V
VCC, machine on Hi-MIC module pin 8 4.7 V ±0.02 V
VDISP, machine on Hi-MIC module pin 4 3.7 V ±0.01 V
Power-up Press ON The prompt appears; after fitting cells, NEW0?: CHECK appears and is cleared with NEW0[9]
Reset Switch off and on several times The machine comes back to the prompt every time

If a function that worked before has stopped, check the polarity of every capacitor you replaced first.

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References

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  1. ↑ 1.0 1.1 1.2 1.3 Sharp, Service Manual, Model PC-1500 & Option, section 6 "PC-1500 key & power supply circuit", printed page 21 (PDF page 23): "10V 220µF × 2" between VGG and GND; 0.1 µF × 2 from the battery lines to F·GND.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Sharp, Service Manual, Model PC-1500 & Option, section 8 "PC-1500 main P.W.B.", printed page 23 (PDF pages 26 to 27): two "10V 220µF" parts beside the 1SS98 and 1588L1 diodes; one "1µF 50V" beside the 2SC2412 and 5.6 kΩ; one "1µF 50V" beside the reset terminal; board marking F2026C.
  3. ↑ 3.0 3.1 3.2 Sharp, Service Manual, Model PC-1500 & Option, section 9 "PC-1500 main circuit diagram", printed page 24 (PDF page 28): reset circuit with TC50H001F, µPD1990AC and two "1µF 50V" capacitors.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Sharp, Service Manual, Model PC-1500 & Option, section 11 "Parts list & guide" (PDF pages 32 to 33): RC-CZ1021CCN1 0.1 µF, RC-CZ1023CCN1 100 pF, RC-CZ1041CCN1 15 pF, RC-CZ1042CCN1 30 pF, RC-EZ105ACC1H 50 V/1 µF, RC-EZ227ACC1A 10 V/220 µF; no designators or quantities.
  5. ↑ 5.0 5.1 Sharp, Service Manual, Model PC-1500 & Option, "6) Power supply circuit", printed page 18 (PDF page 20): VGG 4.7 V, VCC 4.7 V ±0.02 V, VDISP 3.7 V ±0.01 V at 25 °C.
  6. ↑ 6.0 6.1 PC-1500, one of the first EU/US version with A01 ROM, PC-1500.info, 2014-10-11—link(accessed 2026-10-21) Early machine with A01 ROM; boards marked F2075 and F2076; blue wire straps on early A03 machines.
  7. ↑ Sharp, PC-1500 Technical Reference Manual, section 4-2-1, printed pages 88 to 89 (PDF pages 93 to 94): the LH5801 is a CMOS processor. File:Sharp PC-1500 Technical Reference Manual.pdf.
  8. ↑ Sharp, Service Manual, Model PC-1500 & Option, section 5 "Servicing", printed pages 19 to 20 (PDF pages 21 to 22): the FPC is soldered to the key board and crimped to the operation board.
  9. ↑ Sharp Corporation, Service Manual, Model PC-1500 & Option, February 1982, section 1, printed page 2 (PDF page 4): prompt "NEW0?: CHECK" after battery replacement, reset with NEW0. File:Sharp PC-1500 Service Manual.pdf.


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