REV.-A
Symptom
The
+24V
dead.
Vx voltage is not
Outt)ut.
Table 5-6. Power Supply Circuit Unit Repair (cent’d)
Cause
IC
1A is
defective.
Transistors
Q1O
and
Q1
1
are defective.
Q23, Q30, and
ZD 10 defective.
Check Point
Observe the oscillation waveform and the switching
uvaveform.
T
o
k!k!lzk
IV/DIV,
20/.Ls/DlV
Oscillation Waveform (Pin 2 of
IC
1A)
IOV/DIV,
20@DlV
Switching Waveform (Pin 1.1 of
IC
1A)
Observe the chopping wave form
o
Lnn_ll
IOV/DIV,
20/.Ls/DlV
Chopping Waveform (Emitter of
Q1
O)
Observe the Vx voltage, when printer power is turned on.
If
Emitter
v,
, , , , , ,
h-
Collector
t
,1, , , , , , :
2V/DIV,
5@DlV
Vx Voltage Waveform (Q23)
Solution
Replace
IC
1A
Replace
Q1O
or
al
1
Replace
Q23,
Q30
or ZD1 O.
5-19
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