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Sharp PC-1350 Capacitor Replacement Guide

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Sharp PC-1350 main board capacitors (service manual)
C1 (3.3 µF) and C2 to C4 (1 µF) on the PC-1350 main board, with VR1 and the divider resistors (Sharp service manual).

Capacitors in the Sharp PC-1350. The main board has four small polarised capacitors, all identified by designator and value in Sharp's service manual: C1 (3.3 µF) across the supply from the two CR2032 cells, and C2, C3 and C4 (1 µF each) in the LCD bias circuit.[1][2] The CE-201M and CE-202M RAM cards each have one more 1 µF capacitor.[3] The remaining capacitors are ceramics.

The cells are a bigger risk to the board than the capacitors. Check them and the terminals for corrosion first; see Sharp PC-1350 General Maintenance and Battery Explosion, Capacitor or Corrosion Damage.

PC-1350 capacitor list

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PC-1350 main board polarised capacitors (Sharp service manual)
Designator Value Rating Sharp part code Circuit
C1 3.3 µF 10 V RC-SZ1021CCZZ Across the supply from the two CR2032 cells, beside the BD1 diode[1][2][4]
C2 1 µF Not stated RC-SZ1007CCZZ LCD drive and bias circuit, by R10[1][2][4]
C3 1 µF Not stated RC-SZ1007CCZZ LCD bias divider, between R12 and R13[1][2]
C4 1 µF Not stated RC-SZ1007CCZZ LCD bias divider, by R13 and R11[1][2]

The PC-1350 parts list gives no voltage for the 1 µF part. The same Sharp part code, RC-SZ1007CCZZ, is listed as 1 µF 6.3 V in the PC-1250/1251 service manual.[5] Sharp's manuals do not say whether these "RC-SZ" parts are tantalum or aluminium; the board drawing shows them as two-pad surface-mount parts.[2]

Other capacitors in the PC-1350 parts lists[4][6][3]
Board Sharp part code Description
Main RC-CZ1021CCZZ 0.1 µF
Main RC-CZ1035CCZZ 100 pF
Main RC-CZ1037CCZZ 0.01 µF
Main RC-CZ1047CCZZ 0.033 µF
Memory RC-CZ1021CCZZ 0.1 µF
Memory VCTYPU1NX104M 0.10 µF 12 V
CE-201M / CE-202M RC-CZ1021CCZZ 0.1 µF
CE-201M / CE-202M RC-SZ1007CCZZ 1 µF

Signs of trouble

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  • Corrosion or residue round C1, which sits next to the cell supply.
  • A faint or uneven display that VR1 will not correct with fresh cells, which points at C2 to C4 or the divider resistors.[1]
  • Current above Sharp's limits: 20 µA with the power off, 500 µA while displaying.[7]
  • A RAM card that loses its contents early and draws more than its limit (4.0 µA for a CE-201M) on Sharp's 3 V current test.[8]

Replacement

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  1. Remove the RAM card and the cells. Save anything important first.
  2. Use an anti-static strap; the logic is CMOS.[9]
  3. Note the "+" marking of each capacitor on the board and in the layout chart before removing it.[2]
  4. Remove the part with two irons or hot tweezers, clean the pads and fit the new part with the same polarity.
  5. Fit 3.3 µF rated 10 V or more for C1, and 1 µF parts rated at least 6.3 V for C2 to C4, in the same package size.
  6. Refit the cells, reset, and run Sharp's initialisation: CALL &EF88 and POKE &6EAF, 0, each followed by ENTER, with the RAM card out.[10]

Checks after replacement

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After the work (Sharp service manual)[7][10]
Check Expected
Current, power off 20 µA maximum
Current, displaying 500 µA maximum
After RESET and the two initialisation commands RUN MODE screen with the prompt
Contrast with VR1 A clear display can be set
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Sharp, Service Manual, PC-1350, section 10 "Circuit diagram (1)", printed page 13 (PDF page 13): C1 to C4, R1, BD1, VR1, R10 to R13.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Sharp, Service Manual, PC-1350, section 11 "Parts and signal layout chart (main PWB)", printed page 17 (PDF page 17): C1 3.3 µF; C2, C3, C4 1 µF, with polarity marks.
  3. ↑ 3.0 3.1 Sharp, Service Manual, PC-1350, parts list, CE-201M/CE-202M (PDF page 31): items 101 RC-CZ1021CCZZ 0.1 µF and 102 RC-SZ1007CCZZ 1 µF.
  4. ↑ 4.0 4.1 4.2 Sharp, Service Manual, PC-1350, parts list, main PWB unit (PDF page 29): RC-SZ1021CCZZ "10WV 3.3uF"; RC-SZ1007CCZZ "1uF"; ceramic capacitors.
  5. ↑ Sharp Corporation, Service Manual, Model PC-1251, PC-1250, December 1982, parts list (PDF page 18): RC-SZ1007CCZZ capacitor 1 µF 6.3 V. Hosted as File:Sharp PC-1251 Service Manual.pdf.
  6. ↑ Sharp, Service Manual, PC-1350, parts list, memory PWB unit (PDF page 29).
  7. ↑ 7.0 7.1 Sharp, Service Manual, PC-1350, section 4 "Battery life and power consumption", printed page 3 (PDF page 3).
  8. ↑ Sharp, Service Manual, PC-1350, section 9 "RAM card", printed page 12 (PDF page 12).
  9. ↑ Sharp Corporation, Service Manual, PC-1350, code 00ZPC1350SM/E, September 1984, section 1 "Specifications", printed page 1 (PDF page 1). Hosted as File:Sharp PC-1350 Service Manual.pdf.
  10. ↑ 10.0 10.1 Sharp, Service Manual, PC-1350, "Supplement & correction" (PDF page 36).


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