Service manual

REPAIR
Troubleshooting
SERVICE MANUAL
3-10
Problem:
The line feed (LF) motor does not normally.
Points to Check Probable Cause Corrective Action Repair
Is the LF motor turning activated ? is
it noisy?
Defective LF motor Replace LF motor.
Are any motor harness wires
damaged?
Defective motor wiring
harness
Replace LF motor.
Are there binds in the LF motor or
gear train?
Worn, dirty, damaged,
or obstructed gear
train, improper gear
backlash
Clean/remove
obstructions. Space
motor from gear.
Replace damaged
gear(s).
Is the LF motor gear loose or worn? Loose motor screws or
worn LF motor gear
Tighten motor screws.
Replace LF motor.
Is the resistance between the pin 5
of the LF motor and each phase
normal?(about 60
Ω
)Phases
→
A(5-
1); B(5-2);C(5-3); D(5-4)
Defective LF motor
(broken motor wire or
defective connector)
Replace the LF motor
assembly.
Are LF motor drive pulses output
from the pin131-134 of #8 when
printing?
Defective #8 (Main
PCB)
Replace the Main
PCB.
Replace #8.
Is output at the output pin of
transistors Q23-Q26 on and off
according the drive pulses indicated
above?
Defective transistor
Q23-Q26 or circuit on
the Main PCB
Replace the Main
PCB.
Replace Q23-
Q26.
Problem:
The buzzer does not sound.
Points to Check Probable Cause Corrective Action Repair
Are pulses of 4kHz present on one
pin and about 5V present at the
other pin of buzzer BZ1?
If YES, defective
buzzer
If NO, defective Main
PCB.
Replace the buzzer.
Replace the Main
PCB.
Replace #8.
Problem:
Power in on, but nothing appears on the LCD.
Points to Check Probable Cause Corrective Action Repair
Is the contrast setting correct? Faulty contrast
adjustment
Re-adjust.
Is the LCD harness free of
breakage?
Broken LCD harness Replace the harness.
Is the correct voltage (about -16V)
applied to the LCD on pin 2 of
connector CN7 of the Main PCB?
(without 640
×
400 LCD)
Incorrect power supply
voltage to LCD module
Replace the Main
PCB.
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