Repair - Epson PX-8 Technical Manual

REV.-A
6.1 Repair
Before starting the repair
1. Static electricity
• A human being's body is charged with the static electricity which is caused by the friction of his
clothes. If his charged fingers contact the elements of the circuit, the static electricity may da-
mage the elements. Therefore, before starting the repair work, touch the case cover with both
hands to discharge any static electicity.
• When using a measuring instrument, such as an oscilloscope, which needs to be grounded,
touch the conductive portion of the grounding terminal to the case of PX-8 and your fingers,
then connect it to the GND terminal on the board.
• Before repairing the MAPLE board, remove the AC adaptor, the main and auxiliary batteries, and
wait for approximately 30 second before beginning repair. This will allow residual power to dis-
sipate. Handling before total power dissipation may result in damage to the board.
2. Circuit
• After removing the circuit board from the case for repair, rest it on insulative material, to pre-
vent shortcircuits.
• After turning off the power switch, the RAM and a part of IC are backed up by the battery.
Therefore it is necessary to observe the precautions listed above while replacing elements on
the control board.
• Before examining the circuit, check to see if the signal lines are backed up.
• Flexible printed cable (FPC) is used in the mark. If the FPC is bent or scratched, it may result in
circuit damage.
Therefore, handle it very carefully.
4. Connectors
• All internal cable connectors in this device are of locking type. When disconnecting the cables,
unlock the connectors.
5. Soldering
• When repairing the boards, refer to the section on soldering.
6. Storing or transporting circuit boards on which batteries are mounted.
• When storing or transporting circuit boards on which batteries are mounted, protect them from
static hazards by using a static-proof insulator bag, etc. When storing them for a long time, re-
move the battery(s) to prevent battery deterioration or circuit damage due to possible battery
leakage.
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