Unit Troubleshooting - Epson PX-8 Technical Manual

REV.-A
5.4 Unit Troubleshooting
5.4.1 Repairing The MAPLE Board
The following should be noted when repairing the MAPLE board:
1) Check to see that the jumpers and switches are correctly set before proceeding with the repair.
2) Measure the voltage of the main and auxiliary batteries and verify whether the trouble is caused
by insufficient voltage.
3) Care must be used to avoid short circuits on either side of the board. Any short circuit will
short circuit the auxiliary battery resolting in damage to other circuits.
4) Before testing circuit continuity or element function with a circuit tester, make sure that the line
or element to be tested is not backed up by battery. Whenever the battery backed-up line has
to be checked, remove the auxiliary battery from the board before the test.
(Others)
Depending on location of the problem, a MAPLE board failure may present various symptoms and
troubleshooting is harder. Check the computer for any basic problem according to the procedure
below, first. If no problem is found by these checks, use the troubleshooting and repair the test
program and repair flowchart.
(1) Check the jumpers and switches for any improper setting.
(2) Check the logic circuit voltage and clock signal. (Also check fuse F1).
(3) Check the connectors for any imperfect contact.
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