Service manual

REPAIR
SERVICE MANUAL
Troubleshooting
3-11
Points to Check Probable Cause Corrective Action Repair
Is the correct voltage (about 25V-
36V) applied to the LCD on pin 11 of
connector CN8 of the Main PCB?
(640
×
400 LCD)
Incorrect power supply
voltage to LCD module
Replace the Main
PCB.
Is oscillator XT1 operating correctly?
(Use an oscilloscope to check)
Defective XT1 or #7 Replace XT1,
#7.
Do the output pulses from MRD of
#8 change?
Defective #8 Replace #8.
Problem:
LCD displays operates, but data displayed is incorrect (does not match input).
Points to Check Probable Cause Corrective Action Repair
Is solder present at the correct
Country Specification Change-Over
Solder Point?
Incorrect or faulty
solder point for
specified country
(language)
Verify and correct
solder point.
Is there an output wave form at each
pin in the connector CN7 or CN8
Defective #8 or solder
bridge
Replace the Main
PCB.
Replace #8.
Is there faulty soldering the LCD
module?
Replace the LCD
module.
Do the CBIC (#8) MA0-MA14 pulses
change sequentially
Defective #8 Replace #8.
Do video RAM (#6) MD0-M7 change
in response to the MA0-MA14
pulses?
Defective #6 Replace #6.
Problem:
Word processor prints when no paper is set, or will not print when paper is set (Paper
End Sensor malfunction)
Points to Check Probable Cause Corrective Action Repair
Is the PE(paper end) switch properly
installed?
Incorrect installation Reinstall.
Is the PE switch lever stuck? Incorrect installation Reinstall.
Is the PE switch damaged? Replace the PE
switch.
Does pin 1 of CN14 go LOW when
paper is not set and HIGH when
Paper is set?
Harness wire break or
defective PE switch
Replace the harness
or the PE switch.
Does the switch function abnormally
even though the above signals are
normal?
Defective #8 Replace the Main
PCB.
Replace #8.
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