Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
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TROUBLESHOOTING
1. TV/CATV(Analog) doesn’t display
2. Video doesn’t display
Check T U 1 Pin 23(Vid eo output )
Can you see t he normal signal?
Check th e in pu t(Pin 1) of Low-Pass F ilter
(IC808).
Can you see t he normal wavefo rm?
Check th e output(p in 8) of Low-Pass
Filter(IC808).
Can you see t he normal wavefo rm?
Check the Capaciter(C658) in fro nt of
BCM3552 ch ip .
Can you see t he normal wavefo rm?
YES
YES
YES
NO
Could you measu re VCC voltage(5Pin ) of
TU801 & IIC lines(8,9Pin )?
Are they all normal?
YES
You sh ou ld rep lace TUNER.
NO
After ch eckin g th e C800(0.1uF Cap), you can
suspect that PCB is bad.
NO
After ch eckin g th e Power of L ow-Pass F ilter you
should decide to replace Low - Pass Filter or not.
NO
After ch eckin g th e pattern between pin8 of IC808
and C658, you can su sp ect th at PCB is bad ..
YES
This bo ard has b ig problem becau se Main
chip(BCM3 552) have some trouble s.
Afte r c hecking thoro ugh ly all pa th onc e again,
You sh ou ld decid e to rep lace BCM3 552 or not.
Check JP7004.
Can you see t he normal wavefo rm?
Check the R707.
Can you see t he normal wavefo rm?
YES
YES
NO
JK70 1 may have problem. Replace th is
Jack.
Check the C651 in fro nt of BCM3552 ch ip .
Can you see t he normal wavefo rm?
NO
rep lace Part R707.
YES
This bo ard has b ig problem becau se Main
chip(BCM3 552) have some trouble s.
Afte r c hecking thoro ugh ly all pa th onc e again,
You sh ou ld decid e to rep lace BCM3 552 or not.
NO
After ch eck th e pattern between R707 and C651,
You can su spect that PCB is bad.
