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Copyright©2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
TROUBLE SHOOTING GUIDE
TV/CATV(Analog ) doesn t display
Check TU1 Pin16(Video output)
Can you see the normal signal?
Check the input(Pin1) of Low-Pass Filter
(IC808).
Can you see the normal waveform?
Check the output(pin8) of Low-Pass
Filter(IC808).
Can you see the normal waveform?
Check the Capaciter(C658) in front of
BCM3553 chip.
Can you see the normal waveform?
YES
YES
YES
NO
Could you measure VCC voltage(3Pin) of TU1 & IIC
lines(7,8Pin)?
Are they all normal?
YES
You should replace TUNER.
NO
After checking the C800(0.1uF Cap), you can
suspect that PCB is bad.
NO
After checking the Power of Low-Pass Filter you
should decide to replace Low-Pass Filter or not.
NO
After checking the pattern between pin8 of IC808
and C658, you can suspect that PCB is bad..
YES
This board has big problem because Main
chip(BCM3550) have some troubles.
After checking thoroughly all path once again,
You should decide to replace BCM3553 or not.