Epson DLQ-3000 Service Manual page 151

DLQ-3000+
Condition
T T
Symptom : Normal voltage is not output. (continued)
(continued)
T101 or T201 is
All output defective.
voltages are
abnormal.
Diode D151 or
D251 is
defective.
Over current
protection circuit
is defective.
Over voltage
protection circuit
is defective.
Notes:
1. Degradation of a component behind the secondary coil may suppress the T101/ T201
output voltage.
2.
Once PC102 ( photo-thyristor) turns on, it does not turn off until C111 is discharged. Therefore, be
sure to wait for a few minutes before turning the power on again.
5-12
Table 5-9. C124 PSB/PSE Board Repair (continued)
Cause
Check T101/T201 for the followings:
Pins 6/7 for the input voltage to the
primary coil
Output voltage of the corresponding
pins on the secondary side.
(See Note 1.)
Check that the correct voltage (+35V)
is output from the both terminals of
C151/C251.
If no voltage is output, T101/T201 is
defective.
Check the transistor Q154.
(Collector is at Gp level.)
If it's on, Q153/Q253 or other
peripheral circuit part is defective.
If it's off, PC102 or components
behind or Q101/Q201 in the main
switching circuit is defective.
Y
Check the transistor Q155.
(Collector is at Gp level.)
If it's on, Q155, ZD153 or a peripheral
part of Q155 is defective.
If it's off, a circuit part behind PC102
or Q102 in the main switching circuit
is defective.
Y
Check if Q155 is on because the
voltage for +5 V line is abnormally
high.
If it's on, IC151 or a peripheral
circuit part is defective.
If it's off, PC102 is defective.
(See Note 2.)
Check point Solution
Replace the
PSB/PSE board,
T101/T201 or any
associated
defective
component.
Replace the
PSB/PSE board,
D151/251 or any
associated
faulty part.
Replace the
PSB/PSE board,
Q154 or any
associated
faulty part.
Replace the
PSB/PSE board,
Q155 or any
associated
faulty part.
Rev. A