3-2
Replace Q908
and Q909.
1. Power Circuit
• Input Voltage : 90V - 135V
• It is possible to malfunction, if the unload condition is left for a long time when power is on.
(More than Dummy load 100mA)
• A Primary side is abnormal when the fuse is short, secondary side is abnormal when the IC103 oscillates
intermittently.
• The resistor value of both terminal is measured with DVM crossing each other to check the each element is
normal or abnormal. (It is normal when the numerical value is different each other.)
ELECTRICAL TROUBLESHOOTING GUIDE
Is F901 normal?
Is IC901 Pin
3
switching normally?
<Fig.3-1>
A primary side is abnormal.
Check the GND of C901 and
IC901 Pin
3
with oscilloscope.
When IC901
oscillating
Secondary side
is abnormal.
In condition of DC140V.
(Feedback is abnormal)
After connect
CON903
Pin
1
,
3
short.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
(Fig. 3-1) IC901 Pin
3
Normal switching waveform on the
stand-by mode at the AC110V
NO
NO
NO
NO
NO
NO
NO
NO
Is CN903 Pin
3
5.2V?
Is voltage of BD901 140V?
Are R907, D902,
D903 and R902
normal?
Are D901, R904,
R905 and R906
normal?
Is PC901 normal?
Are CON902
Pin
5
,
6
and
9
5V?
Is CON904 Pin
3
8V?
Is CON902 Pin
3
12V?
Are CON903 Pin
5
-24V, Pin
7
-20V and
Pin
8
-16V?
END
END
(A)
To (A).
START
Does oscillate
continuously when
the CON903 is
disconnected ?
Front Circuit
Board is
abnormal
Are D908, D909,
D907, D910, D906
and D905 normal?
Replace
defective
parts.
Check Q904
and ZD903.
Replace
IC902.
Replace defective
parts.
Check or
replace
D908.
Are R922, C927,
R921 and R918
normal?
Is CON903 Pin
3
5.2V?
Is IC905
normal?
w
w
w
.
r
t
v
-
h
o
r
v
a
t
-
d
j
.
h
r
