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Sharp PC-1500A Capacitor Replacement Guide

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Sharp PC-1500A reset terminal and 1 µF capacitors (service manual)
The reset terminal and the two 50 V 1 µF capacitors on the PC-1500A main board (Sharp PC-1500A service supplement).

Capacitor replacement on the Sharp PC-1500A. Sharp marks the PC-1500A's key and power supply circuit "same as PC-1500", and the PC-1500A main board drawing shows the same four electrolytic capacitors: two 10 V 220 µF next to the input diodes and two 50 V 1 µF beside the reset terminal.[1][2] The PC-1500A supplement's parts list adds no electrolytic capacitor, so the part codes are those in the PC-1500 parts list.[3][4]

As on the PC-1500, the AA cells and their leakage are the bigger risk to the board. Clear any battery corrosion before recapping; see Sharp PC-1500A General Maintenance and Battery Explosion, Capacitor or Corrosion Damage.

PC-1500A capacitor list

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Sharp's parts lists give no circuit designators, so the capacitors are described by position on the PC-1500A main board drawing.[2][4]

PC-1500A electrolytic capacitors
Qty Value Rating Sharp part code Circuit Position on the PC-1500A main board
2 220 µF 10 V RC-EZ227ACC1A Between VGG and ground at the output of the Hi-MIC regulator module[1][5] Beside the 1SS98 and two 1S1588 diodes, next to the module pads (VBAT, VGG, BFO, VCC, GND, VDISP, VA)[2]
2 1 µF 50 V RC-EZ105ACC1H Power-on reset circuit[6] Side by side to the right of the reset terminal[2]
Sharp PC-1500A main board power section (service manual)
The two 10 V 220 µF capacitors beside the input diodes on the PC-1500A main board (Sharp PC-1500A service supplement).

The placement of the 1 µF pair differs from the PC-1500 board drawing, where one 1 µF capacitor is beside the reset terminal and the other beside the 2SC2412 transistor.[2][7] Work from the PC-1500A drawing, or better from your own board.

The PC-1500A supplement adds a 39 pF capacitor (RC-KZ1022CCN1) to the parts list.[3] The ceramic capacitors in the PC-1500 list (0.1 µF, 100 pF, 15 pF and 30 pF) are on the Sharp PC-1500 Capacitor Replacement Guide; they do not need routine replacement.[4]

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. Photograph both sides of the main board.
  3. Read the value, voltage and polarity of the four electrolytics and compare them with the table.
  4. Note which regulator module is fitted. The supplement allows either the MA1066 or the EHM718L70.[1]

Replacement

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The procedure is the same as on the PC-1500: note the polarity, remove one lead at a time with fresh solder and flux, fit 220 µF parts rated 10 V or higher and 50 V 1 µF parts as Sharp did, and handle the FPC gently while the boards are apart. See the PC-1500 procedure.[4][8]

Checks after replacement

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Targets from Sharp's PC-1500 service manual (same circuit), at 25 °C[9][1]
Check Expected
VGG 4.7 V
VCC, machine on 4.7 V ±0.02 V
VDISP, machine on 3.7 V ±0.01 V
Power-up after fitting cells NEW0?: CHECK, cleared with NEW0[10]
Repeated switch-on Returns to the prompt every time
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References

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  1. ↑ 1.0 1.1 1.2 1.3 Sharp, Model PC-1500A Service Manual, section 5 "PC-1500A key & power supply circuit (same as PC-1500)" (PDF page 4): "10V 220µF × 2"; Hi-MIC "MA1066 or EHM718L70".
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Sharp, Model PC-1500A Service Manual, section 7 "PC-1500A main P.W.B." (PDF page 8): two "10V 220µF" beside the 1SS98 and 1588L1 diodes; two "50V 1µF" to the right of the reset terminal.
  3. ↑ 3.0 3.1 Sharp Corporation, Model PC-1500A Service Manual, October 1982, section 4 "Parts list & guide" (PDF page 3): capacitor 39 pF RC-KZ1022CCN1; no electrolytic capacitors listed. File:Sharp PC-1500A Service Manual.pdf.
  4. ↑ 4.0 4.1 4.2 4.3 Sharp, Service Manual, Model PC-1500 & Option, section 11 "Parts list & guide" (PDF pages 32 to 33): RC-EZ227ACC1A 10 V/220 µF; RC-EZ105ACC1H 50 V/1 µF; ceramic capacitors; no designators.
  5. ↑ Sharp, Service Manual, Model PC-1500 & Option, section 6 "PC-1500 key & power supply circuit", printed page 21 (PDF page 23).
  6. ↑ Sharp, Service Manual, Model PC-1500 & Option, section 9 "PC-1500 main circuit diagram", printed page 24 (PDF page 28): two 50 V 1 µF capacitors in the reset circuit.
  7. ↑ Sharp, Service Manual, Model PC-1500 & Option, section 8 "PC-1500 main P.W.B.", printed page 23 (PDF pages 26 to 27).
  8. ↑ Sharp, Service Manual, Model PC-1500 & Option, section 5 "Servicing", printed pages 19 to 20 (PDF pages 21 to 22).
  9. ↑ Sharp, Service Manual, Model PC-1500 & Option, "6) Power supply circuit", printed page 18 (PDF page 20).
  10. ↑ Sharp Corporation, Service Manual, Model PC-1500 & Option, February 1982, section 1, printed page 2 (PDF page 4). File:Sharp PC-1500 Service Manual.pdf.


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