Repair Of The Control Board - Epson Photo750 Service Manual

EPSON Stylus Photo 750

3.4 Repair of the Control Board

This section describes the problems related to the power supply board. The table below provides various symptoms, likely causes, and checkpoints.
The checkpoints refer to waveforms, resistance, and other values to check to evaluate the operation of each component.
Table 3-7. Repair of the Control Board
Sympto
Condition Cause
m
Reset
circuit is
broken.
ROM is not
The selected
printer correctly.
CPU does
does not
not work.
RAM is
operate at
broken.
all.
CPU is
broken.
Troubleshooting
Check point
Check +5VDC line(Pin 7 of IC8) and
reset signal (Pin 2 of IC8).
5V ײÝ
/RESET
Check that the waveform of Pin 11
of IC3 reverses High/Low.
Check the signal waveform Pin 88
of IC1.
Repair of the Control Board
Table 3-8. Repair of the Control Board
Sympto
Solution Condition
m
Replace
Carriage
IC8.
does not CPU does
operate not work.
correctly.
Replace
T1.
Replace
Q1.
Abnormal PF motor
paper does not
feed. rotate.
Replace
Q2 or
Q3.
Cause Check point
Check the PHASE(Pin 16 and 27) of
IC11 and signal waveform of
OUT(Pin 6,7, 8, and 9).
IC2 is
broken.
IC14 is
broken.
Check the PHASE(Pin 7) of IC 12
and 13, and signal waveform of
OUT(Pin 10 and 15).
IC2 is
broken.
IC12 &
13 are
broken.
Revision A
Solution
Replace
IC8.
Replace
IC11.
If PHASE
signal is
not input,
replace IC.
Replace
IC12 or 13.
45