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REV.-A
Table 5-7.
Board Unit
Symptom
Cause
Checkpoint
Solution
DC voltage is
Transistor
does not
●
Observe the voltage wave-form
Observe the output
at the + 5
turn on.
between the base of Q 1 and pin
voltage waveform of
or +35
6 of
See Figure 5-9.
Q2.
Observe the voltage waveform be-
Replace
or
the base and emitter of
See Figure 5-9.
. Observe the voltage waveform be-
Replace
the collector of Q 1 and pin
6 of
See Figure 5-10.
Triac TY 1 is defective.
.
Check the continuity between
Replace
TY1.
and T2 of TY 1. See Figure 5-11.
OP. AMP.
is
●
Check the voltage between pins 8
Replace 1
defective.
and 2 of
1.
10.6 V)
. Check the voltage between pins 4
and 2 of
1.
10.7
. Check the voltage between pins 1
Measure the voltage
and 2 of ICI.
7.4
between A and K of
or replace IC 1.
+ 12 V line is
Fuse resistor RI 9 (R21)
. Measure the resistance across
Replace
is open.
1).
3.1 ohms)
– 12 V line is
Fuse resistor
. Measure the resistance across
Replace
is
open.
3.1 ohms)
abnormal voltage
Shunt regulator
. Measure the voltage between the
Replace Q4
output to the
is defective.
cathode and anode of
line.
9.0
v + 5 % )
. Measure the voltage between the
gate and anode of
2.5
Photo coupler PC 1 is
●
Measure the voltage between pins
Replace PC 1.
defective.
1 and 2 of the photo diode in
1.
1.1
Zener diode ZD 1 is
●
Confirm the voltage between the
Replace
defective.
anode and cathode of ZD 1.
1.9 V)
NOTE: The parenthesized component numbers indicate those for the
board.
5-18
Summary of Contents for LQ-2550
Page 1: ...L Q 2 5 5 0 TECHNICAL MANUAL EPSON ...
Page 240: ...REV A P r cl Figure 6 3 LQ 2550 Lubrication and Adhesive Application Points Diagram 2 6 3 ...
Page 241: ...REV A 7 i_ Figure 6 4 LQ 2550 Lubrication and Adhesive Application Points Diagram 3 6 4 ...
Page 252: ...REV A I 1 I 7 v m o m x b Figure A 6 PPD781OHG Block Diagram A 7 ...
Page 297: ...REV A 1 L I Irl N I i t 1 I I x Figure A 50 ROPSE Board Circuit Diagram A 52 ...