An Introduction To Troubleshooting; Test Program - Epson PX-8 Technical Manual

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5.1 An Introduction to Troubleshooting
Troubleshooting is usually to easy; vaned symptoms appear depending on points of failure. This
section describes two procedures which may allow easier troubleshooting and subsequent repair:
1. Check-out procedure
Objective: To guide the user through a problem isolation process when symptoms do not indi-
cate a specific component malfunction.
Fault isolation level: Repair by unit replacement, repair can be accomplished with a basic know-
ledge of computer hardware.
2. Unit repair flowchart
Objective: To guide the user through a component level repair process.
Allow a component-level repair of an individual faulty unit.
Fault isolation level: Component level - Requires an advanced knowledge of computer hardwa-
re engineering, and electronics.
General troubleshooting procedure
• First, isolate and replace the faulty unit according to the check-out procedure faulty each time a
unit is replaced, to make sure the new unit is not faulty. This process will prevent confusion
with a problem caused by poor connector contacts.
• Second, isolate and replace the faulty component in the unit according to the appro-
priate unit flowchart or the trouble table.
Step 1
Check-out
procedure
Repair by unit
replacement
)
Step 2
Unit repair
flowchart
Repair at com-
ponent level
Note 1) All checks indicated on the flowchart must be made.
Should any unit or component be replaced disregarding any check, the newly installed
one might be damaged.
Note 2) Whenever you are lost in the repair procedure, return to the entry and restart the
procedure.
Note 3) When no exit is found, during a diagnostic procedure (e.g., the test process has resul-
ted in repeating a diagnostic loop), proceed with the repair according to the trouble ta-
ble.
5.2 Test Program
A test program is supplied stored in an E-PROM with carrier which can be installed in the com-
puter ROM capsule. The test program provides tests for the ten functions listed in Table 5.1. It al-
lows either one of the following two execution modes
• AUTO Modo
In this mode, the program automatically performs a six test cycle. If desired, the cycle may be
repeated up to 99 times. The number of cycles may be selected after loading the program. This
mode is suitable for an aging test after repair or a test on a problem of very low reproducibility.
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