Epson DLQ-3000 Service Manual page 152

Condition
T T
Symptom : Normal voltage is not output. (continued)
(continued) +35 VDC
All output stabilizing circuit
voltages are is defective.
abnormal.
Output of +5 V IC151 is
is abnormal, defective.
while output of
+35 V is normal.
Smoothing
circuit is
defective.
Rev. A
Table 5-10 . C124 PSB/PSE Board Repair (continued)
Cause
Check the waveform output from pin
4 of the photo-coupler PC101/ PC201 is
as shown below. (Constant wave-
form should be output when the
printer is in normal and stand-by
status.)
If the correct waveform as shown
below is output, check Q101/Q201 for
the switching waveform. Then,
check operation of the Q102/Q202,
Q103/Q203 and peripheral circuit
parts.
If the waveform is abnormal,
PC101/PC201, ZD151, ZD181–ZD185
or any peripheral circuit part is
defective.
Check pin 21 of IC151 for the output
voltage.
If it's abnormal, IC151 is defective.
Check if the correct voltage
(approximately 5 V) is input between
(+) and (-) terminals of IC154.
If not, L151 or C154 is defective.
Check point
Figure 5-10. PC101/PC201 Waveform
Troubleshooting
Solution
Replace the
PSB/PSE board
or any
associated
faulty part.
Replace the
PSB/PSE board,
IC151 or faulty
peripheral parts.
Replace the
PSB/PSE board,
L151, or C154.
5-13