Sharp PC-1245 General Maintenance

Resetting the PC-1245: hold down any key and press the RESET button on the back with a ball-point pen (Sharp instruction manual).

Routine care of the Sharp PC-1245. The machine runs at 6 V from two CR2032 lithium cells and has no mains voltage inside, so maintenance is about the cells, the reset button, the contrast control and cleaning.

Cells

PC-1245 cells (Sharp)

Item	Detail
Type	Two CR-2032 lithium cells; 6.0 V DC
Life	About 300 hours of use at 0.03 W
When to replace	The display stays dim and hard to read from the front even with the contrast control turned fully anticlockwise
Rules	Replace both cells together; do not mix a new cell with a used one

The manual says to record programs and data on tape through the CE-125 before replacing the cells, and to press RESET after fitting new ones, so expect to lose the memory.

Replacing the cells

Sharp's procedure:

1. Set the power slide switch to OFF.
2. Remove the screws from the back cover with a small screwdriver.
3. Slide the cell cover off in the direction of the arrow.
4. Replace both cells.
5. Slide the cell cover back.
6. Hook the claws of the back cover into the slits in the case.
7. Push the back cover in slightly while refitting the screws.
8. Switch on and press the RESET button to clear the computer. The prompt > should appear. If the display is blank or shows any other symbol, take the cells out, refit them and check again.

Sharp's manual warns that a dead cell left in the computer can leak and damage it; remove dead cells promptly, and take the cells out if the computer will not be used for a long time. For dealing with corrosion, see Battery Explosion, Capacitor or Corrosion Damage.

Reset

The RESET button is on the back. Press it with a ball-point pen, not a mechanical pencil or a needle.

• Hold down any key and press RESET. This resets the PC-1245 and keeps all programs, variables and reserve memory.
• If there is still no response from any key, press RESET without holding a key. This clears the program, the data and all reserved contents, so use it only when necessary.

Contrast

The contrast control is on the right of the computer. Turn it in the direction of the arrow for a clearer display and the other way for a dimmer one, and set it so that the display is easy to read. If the display stays dim with the control at its limit, the cells are exhausted.

Cleaning and handling

Sharp's maintenance notes for the PC-1245:

• Handle the computer carefully: the LCD is glass.
• Keep it away from extreme temperature changes, moisture and dust, and out of vehicles parked in direct sun.
• Clean it with a soft, dry cloth only. Do not use solvents, water or wet cloths.
• Strong static electricity or external noise can make it hang with all keys dead. Hold any key and press RESET.

Inside the case

No service manual or board drawing for the PC-1245 is available, so open it with care and photograph each stage. The Sharp PC-1251 General Maintenance page records Sharp's service precautions for the PC-1250/1251 board, a different model in the same series, including the warning that a poorly seated cell can cause a flickering display or damage other parts; treat them as a guide only, since the boards may differ.

Capacitors

No capacitor values have been published for the PC-1245. See Sharp PC-1245 Capacitor Replacement Guide.

Preventive maintenance checklist

1. Save programs to tape before any cell work.
2. Remove the cells for storage and inspect the terminals.
3. Wipe the case with a soft, dry cloth.
4. Check that the contrast control gives a clear display with fresh cells.
5. Check every key and the ON/BRK key.

Related pages

• Sharp PC-1245
• Sharp PC-1245 Troubleshooting Guide
• Sharp PC-1245 Capacitor Replacement Guide
• Sharp PC-1245 Instruction Manual
• Sharp PC-1251 General Maintenance
• Recommended Tools