Electrical Troubleshooting; Guide; Power(Smps) - LG LH-CX640 Series Service Manual

3-4
ELECTRICAL
TROUBLESHOOTING
GUIDE
1.
Power(SMPS)
CIRCUIT
NO
5.3VA.
Replace the
F101.
(Use
the
same
Fuse)
Is
the
F101
normal?
Is the
TH101
normal?
Is
the
BD101
normal?
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
Replace
the
BD101.
Replace
the
TH101.
Is the
D105
normal?
Check
or
Replace
the
D105.
Replace the
D129.
Replace
the
IC106.
Replace
the
D127.
Replace
the
D126.
Replace
the
D125.
Replace
the
D124.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
Is
Vcc(12~28V)
s up-
plied
to
IC104
Pin3?
Is
the
D129
nor-
mal?
Is
there
about
2.5V
at
the
IC106
Vref?
Is
the
D127
normal?
Is
the
D126
normal?
Is the
D125
normal?
Is
the
D124
normal?
Check
the
Main
PCB
Power
supply
Line
short?
(1)
No
5.3VA(SYS/Hi-Fi/TUNER)
NO
5.0VA.
Check
or
Replace
the
D129.
Is there
about
5.3V
at
the
Q168
Emitter?
Does
the
\"H\"
signal
appear
at the
Q162?
Check or
Replace
the Q162.
NO
Check
the
\316\274-com
PWRCTL
'H'
NO
YES
YES
YES
(2) No
5.0VA
NO
3.3VA.
Check
or
Replace
the
D127.
Is
there
about
3.8V
at
the
IC162
Pin1?
Check or
Replace
the
IC162.
NO
YES
YES
(3)
No
3.3VA
NO
12VA.
Check
or
Replace
the
D126.
Is
there
about
13V
at
the
Q161
C?
Check or
Replace
the Q161.
NO
YES
YES
(4)
No 12VA
NO
NO
NO
NO
NO