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Sharp PC-1500A General Maintenance

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Sharp PC-1500A
A Sharp PC-1500A (photo: striegel, CC BY 2.0)

Routine care of the Sharp PC-1500A. Sharp's service supplement says the PC-1500A is a revised PC-1500 with more memory and that its key and power supply circuit is the same as the PC-1500's, so the cells, cleaning, keyboard, display and module compartment are looked after exactly as on the PC-1500.[1][2] The shared procedures, with Sharp's references, are in Sharp PC-1500 General Maintenance; the points below are specific to the PC-1500A.

Cells and memory

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The PC-1500A takes the same four AA (UM-3) cells as the PC-1500.[2][3] On the PC-1500, a battery change clears the memory and is followed by the NEW0?: CHECK prompt, and the PC-1500A behaves the same way because its circuit is unchanged.[4][5][1] The PC-1500A has 5946 bytes for BASIC programs and data and a 1024-byte machine-language area, against 1850 bytes and none on the PC-1500, so there is more to lose.[1] Save programs to cassette through the CE-150 before taking the cells out.

PC-1500A cell care (Sharp)
Point Detail
Cells Four AA (R6, UM-3) 1.5 V dry cells; rechargeable cells cannot be used[3][2]
Changing Replace all four together; procedure in Sharp PC-1500 General Maintenance[3]
Storage Remove the cells; a dead cell left in the machine can leak[6][3]
Battery terminals Part of the bottom cabinet; the PC-1500A's bottom cabinet with battery terminal is part DUNTG7562CCZZ, and its battery lid GFTAB1266CCO1[7]

For cleaning up leaked electrolyte, see Battery Explosion, Capacitor or Corrosion Damage.

Cleaning, keyboard and display

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Sharp's operational notes apply unchanged: a soft, dry cloth only, no solvents, water or wet cloths, and care with the glass LCD.[6] The key rubber, key board, FPC and LCD rubber connectors are built as on the PC-1500, and the PC-1500A has its own part codes for the key board unit (DUNTK7529CCZZ) and the calculation board unit (DUNTK7530CCZZ).[7] For key contact cleaning, the FPC and the LCD connectors, follow Sharp PC-1500 General Maintenance.

Module compartment

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All PC-1500 options can be used with the PC-1500A, including the CE-151, CE-155 and CE-159 memory and program modules on the 40-pin connector.[1] On the PC-1500A the chip-select lines on that connector are named S3, S4 and S5 instead of S1, S2 and S3.[1] Do not touch the connector in the module compartment; Sharp warns that static electricity can damage the computer.[3]

RAM

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The PC-1500A's RAM is four HM6116 chips. The PC-1500's two TC5514P system RAM chips are not fitted.[1] The machine is CMOS throughout, so handle the main board with an anti-static strap.[8]

Capacitors

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The PC-1500A has the same four electrolytic capacitors as the PC-1500: two 10 V 220 µF on VGG and two 50 V 1 µF in the reset circuit. On the PC-1500A board both 1 µF capacitors sit beside the reset terminal.[9] See Sharp PC-1500A Capacitor Replacement Guide.

Preventive maintenance checklist

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  1. Save programs to cassette before any battery work.
  2. Remove the cells for storage and inspect the compartment and terminals.
  3. Wipe the case with a soft, dry cloth.
  4. Keep the 60-pin connector cover fitted and the module lid closed.
  5. Check every key, including ON/BREAK, and the display.
  6. Check the supply voltages against the PC-1500 figures if the machine misbehaves; see Sharp PC-1500A Troubleshooting Guide.
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Sharp Corporation, Model PC-1500A Service Manual, October 1982, sections 1 to 3 (PDF page 2): revised PC-1500 with more memory; RAM change; specification change; 40-pin connector signal names; programs and all PC-1500 options usable. File:Sharp PC-1500A Service Manual.pdf.
  2. ↑ 2.0 2.1 2.2 Sharp, Model PC-1500A Service Manual, section 5 "PC-1500A key & power supply circuit (same as PC-1500)" (PDF page 4): UM-3 × 4.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Sharp, PC-1500 instruction manual, appendix B "Battery replacement for the PC-1500" (PDF pages 144 to 145).
  4. ↑ Sharp, PC-1500 instruction manual, chapter II, "I. Variables" (PDF page 26): information is retained until, among other things, the batteries are changed.
  5. ↑ Sharp Corporation, Service Manual, Model PC-1500 & Option, February 1982, section 1, printed page 2 (PDF page 4): the reset prompt after battery replacement. File:Sharp PC-1500 Service Manual.pdf.
  6. ↑ 6.0 6.1 Sharp, PC-1500 instruction manual, "Operational notes" (PDF page 4). File:Sharp PC-1500 Instruction Manual.pdf.
  7. ↑ 7.0 7.1 Sharp, Model PC-1500A Service Manual, section 4 "Parts list & guide" (PDF page 3).
  8. ↑ Sharp, PC-1500 Technical Reference Manual, section 4-2-1, printed pages 88 to 89 (PDF pages 93 to 94). File:Sharp PC-1500 Technical Reference Manual.pdf.
  9. ↑ Sharp, Model PC-1500A Service Manual, section 7 "PC-1500A main P.W.B." (PDF page 8).


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