LG 37LC7D (CHASSIS:LB73A) Service Manual ▷ View online
- 13 -
TROUBLESHOOTING
Check TU800 Pin8(Video output)
Can you see the normal signal?
YES
Could you measure voltage of TU800 & IIC
lines?
Are they all normal?
You should replace TUNER.
YES
NO
Check the input(Pin63) of AV switch(IC603).
Can you see the normal waveform?
YES
Check the output(Pin56) of AV switch(IC603).
Can you see the normal waveform?
YES
Check the input(Pin148) of Decorder(IC901).
Can you see the normal waveform?
YES
Check the output signal of Decorder(IC901).
Can you see the normal waveform?
Check the input and output of HD2.4(IC401).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
YES
After checking the Power of AV switch you
should
decide to replace AV switch or not.
After checking the Power of AV switch you
should
decide to replace AV switch or not.
After checking the Power of Decorder you should
decide to replace Decorder or not.
After checking the Power of Decorder you should
decide to replace Decorder or not.
This board has big problem because Main
chip(HD2.4) have some troubles.
After checking thoroughly all path once again,
You should decide to replace HD2.4 or not.
You should check power lin & IIC lines.
NO
NO
NO
NO
NO
NO
TV/CA
TV doesn’t display
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Check the output data of TU800 Pin 21~28
Can you see the normal signal?
YES
Could you measure voltage of TU800 & IIC
lines?
Are they all normal?
You should check power line & IIC lines.
You should replace TUNER.
YES
NO
Check the input and output of HD2.4(IC401).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
This board has big problem because Main
chip(HD2.4) have some troubles.After checking
thoroughly all path once again, You should
decide to replace HD2.4 or not.
NO
NO
DTV doesn’t display
- 15 -
Check J603( Pin 7B) , P601 (Pin 1)
Can you see the normal waveform?
YES
J603 or SIDE AV may have problem. Replace
this Jack or SIDE AV.
After checking the Power of AV switch you
should decide to replace AV switch or not.
NO
Check the input(Pin1 or Pin22) of AV
switch(IC603). Pin1 is for video1,Pin22 is for
video 2.
Can you see the normal waveform?
NO
YES
YES
YES
YES
After checking the Power of AV switch you
should decide to replace AV switch or not.
Check the output(Pin56) of AV switch(IC603).
Can you see the normal waveform?
NO
After checking the Power of Decorder you should
decide to replace Decorder or not.
Check the input(Pin148) of Decorder(IC901).
Can you see the normal waveform?
NO
After checking the Power of Decorder you should
decide to replace Decorder or not.
Check the output signal of Decorder(IC901).
Can you see the normal waveform?
NO
This board has big problem because Main
chip(HD2.4) have some troubles.
After checking thoroughly all path once again,
You should decide to replace HD2.4 or not.
Check the input and output of HD2.4(IC401).
Especially you should chec
The H,V sync and clock.
Can you see the normal waveform?
NO
V
ideo doesn’t display
- 16 -
Check J601,J602.
Can you see the normal waveform?
YES
J601,J602
may have problem. Replace this Jack.
After checking the Power of component switch,
you should decide to replace component switch
or not.
NO
Check the input of Component switch(IC707) ,
Can you see the normal waveform?
NO
YES
YES
YES
YES
After checking the Power of component switch
you should decide to replace component switch
or not.
Check the output of Component switch(IC707) ,
Can you see the normal waveform?
NO
After checking the Power of MST3361 you
should decide to replace MST3361 or not.
Check the input of MST3361(IC703 Pin41,44,46).
Can you see the normal waveform?
NO
After checking the Power of MST3361 you
should decide to replace MST3361 or not.
Check the output of MST3361(IC703 ).
Can you see the normal waveform?
NO
This board has big problem because Main
chip(HD2.4) have some troubles.
After checking thoroughly all path once again,
You should decide to replace HD2.4 or not.
Check the input and output of HD2.4(IC401).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
NO
Component doesn’t display
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