Epson LQ-1050 Technical Manual page 185

Symptom
+5 V line is dead.
+35 V line is
dead.
—
+35 V line is less
than normal.
Normal voltage:
+35 v A 10 %.
Table 5-7. MONPS/MONPSE Board Unit Repair
Cause
+35 V line is dead.
Input filter circuit
malfunction
open between
is
the collector and
emitter.
R5 is open.
Malfunction in the over Voltage at each terminal under
voltage detection cir-
cuit for the transformer
secondary side.
Current flowing
through the base of Q 1
is less than normal.
Checkpoint
Refer to the checkpoint list for the
+35 V line.
Check the input voltage waveform
at the DB 1 input terminal.
Check the voltage waveform at
the T 112-14 terminal.
Check the resistance across
Check the resistance across
normal conditions.
PC1 -GP: approx. 29.9 ~]
pin of
. cathode-anode of Q20: approx.
. Check the resistance value
across R4.: Approx. 27 [Q]
Check whether D2 is open.
Check whether Q2 is shorted.
5-13
Solution
Replace IC20.
Check whether the
input filter circuit
is partly shorted or
open.
Replace Q1.
. Replace R5.
. Replace R14.
Replace the defec-
tive part.
32.6 @/l