Epson Stylus 820 Service Manual page 89

Troubleshooting
5.3 Unit Repair - C160 Main Control Board
This section describes the problems related to the main controller board (C160 MAIN). The table below
provides various symptoms, likely causes, and checkpoints. The checkpoints refer to waveforms, resistance,
and other values to be checked to evaluate the operation of each component.
Phenomenon Condition
It does not
CPU does
operate at all.
not operate.
Gate array
does not
operate.
Self-test Gate array
printing does not
does not operate.
abnormal.
Common
driver circuit
does not
operate.
5-4
Table 5-4. Repair of C160 MAIN
Cause Checkpoints
Reset circuit Check the wave-form
does not at either pin 1 and 4(GND).
operate.
CRU1 or IC2 Does wave-form of CRU1 is correct?
is defective. (at either pin 37 and 38 of CPU)
CRU2 or IC1 Does wave-form of CRU2 is correct?
is defective. (Refer to above wave-form.)
OE signal Check the wave-form at the pin
does not (52,54,56,57,58).
output.
Does PWM wave-form is correct?
PWM signal
(Check the pin at 140.)
does not
output.
Tr does Check the wave-form at the pin 3 of QM3.
not operate.
Stylus Color IIs / Stylus 820
Solution
Replace IC13.
Correct : replace IC2.
Incorrect : replace
CRU1.
Correct : replace IC1.
Incorrect : replace
CRU2.
Replace IC1.
Replace IC1.
Replace a defective
element.(QM1,2,3,4,
5,6,7,8 or Q1,7,8.)
Rev. A