Read LG 42LH70YD (CHASSIS:LJ91D) Service Manual online
3. Digital TV Video Trouble Shooting
Check RF Cable
Y
Check TP Clock, Data, Sync
R107, R108, R109
N
Maybe Tuner(TU101) has problems
Y
Maybe BCM3556(IC100)
has problems
Check Tuner(TU101) Power
(5.0V, 2.5V, 3.3V, 1.2V)
N
Replace one of IC101, IC102 at
Jack Board or IC803/ IQ812/ C804/
Q809/+5V_ST and +12V of P801 at
Main Board& Recheck
Y
Check cable between P203 at Jack
Board and P701 at Main Baord
N
Maybe Cable Pin has problems
Y
Click on the first or last page to see other 42LH70YD (CHASSIS:LJ91D) service manuals if exist.