Service manual

16
Model No: 21WHS3-Bn
Version 1.0
FAULT FINDING TREES
A Three-None(no raster, no picture, no sound)
This failure is mainly caused by big-power circuit such as power supply, horizontal scanning, vertical scanning.
The detail checking and repairing steps are as follow.
0V
4.5-5.5V
YES
0V
＞
1V
0.6V
300V
NO
YES
0V
300V
0V
0V
115V
No variation
Normal
115V
0V
Others
24V
2V
8V
115V
LOW
NO
variation
＜
50V
Test the voltage of C528B
Cut off R458
T
T
T
e
e
e
s
s
s
t
t
t
o
o
o
t
t
t
h
h
h
e
e
e
r
r
r
v
v
v
o
o
o
l
l
l
t
t
t
a
a
a
g
g
g
e
e
e
s
s
s
u
u
u
c
c
c
h
h
h
a
a
a
s
s
s
1
1
1
8
8
8
8
8
8
V
V
V
,
,
,
2
2
2
4
4
4
V
V
V
,
,
,
a
a
a
n
n
n
d
d
d
1
1
1
2
2
2
V
V
V
VD525,VD1561,VR501,V542,
VD1517,V504,V1511
Check VD522,C528B
Recover R458, unplug
XS403 for a While,then
test the voltage of C528B
Check V451,T451,T450,
Deflection coil
Check L452,VD436,C461
Deflection coil
Voltage of C507
Check if V1513 collect-emitter
Was broken down
Check XR502,F501,power
Swich, AC cord and plug
Check the voltage
of V1513 collector
Check V1513,V1512,F501,XR502,VD503
Check T501
Test voltage of V1513 base
Check T501,VD1517,
C1515,C1517,V451,
VD522-VD529
C455,C456,T451
C467
Check if it get right
When cut off V504
Test the voltage of
N301 pin1
CPU has sent the
Power-off signal
Check if V504
is broken down
Check V1513
Check R539,V1553,VD1561
N
504,V1511,V1512,R556
N301 pin39voltage
N301 pin33 voltage
Check N301,N401
V450 pin C voltage
Check VD543,C525,
]R454,C453,T450,
C455,V451
Check R452,V450
Check T451
Check V451 pin C voltage
Check T451,V451,R458
＞
130V
Others
115V
0V