Repair Of C124 Psb/Pse Board - Epson DLQ-3000 Service Manual

5.3 Repair of C124 PSB/PSE Board

This section describes how to repair the PSB/PSE board to the component. Table 5-8 shows the
abnormal conditions and corresponding causes, check points and solutions. Select the condition
from the table and perform any necessary check and repair.
Condition
T T
Symptom : Normal voltage is not output.
Fuse is blown Line filter circuit
out soon after is defective.
replaced.
Rectification or
smoothing
circuit is
defective.
All output Diode bridge
voltages are DB101 is
abnormal. defective.
(Due to the
circuit structure,
when the +35 V
output is Soft start circuit
abnormal, all (surge circuit) is
other output defective.
voltages are
affected.)
Switching FET
Q101 or Q201 is
defective.
Notes:
1. DB101 is possibly shortened as a result of the short circuit of other components behind DB101 .
2. Degradation of some component behind DB101 may suppress the DB101 output voltage
Rev. A
Table 5-8. C124 PSB/PSE Board Repair
Cause
Check C1 to C4 or L4 for a short circuit
with the AC line.
Check the followings for short circuit:
DB101
All (+) terminals between C111 and
DB101
T101 and T201
(See Note 1.)
Check that the voltage output from
pin 3 (+) and pin 4 (-) on DB101 is as
follows:
C124 PSB : Approximately 170V
C124 PSE : Approximately 300V
(See Note 2.)
Y
Check that DC voltages at the both
ends of R2 and R3 are 0 V.
Y
R2 and R3 are open, TY101 is bad,
or R124, D103, or T101/201 which
are used to turn on TY101 is bad.
Check for the correct switching
operation of Q101/201 by checking if
the waveform output from pins 6 and
7 of the T101/201 primary coil is
correct, as shown below.
Figure 5-9. Switching Waveform
Check point
Troubleshooting
Solution
Replace any
defective
component.
Replace the
PSB/PSE board,
DB101 or any
associated
defective
component.
Replace the
PSB/PSE board,
DB101 or any
associated
defective
component.
Replace PSB/
PSE board or
any associated
defective
component.
Replace the
PSB/PSE board,
DB101 or any
associated
defective
component.
5-11