LG RH4820W Service Manual page 19

YES
IC807 - 2 : Check SIF
signal input
YES
When changing a channel, IC702 -
69 : HIGH after RESET signal
YES
IC702 - 39 :
No Sync signal input
YES
No TUNER VIDEO signal
input
YES
Check TUNER power
and other circuits
NO
Check C866, TUNER
signal flow
NO
Check IC702 power and
other circuits
NO
Check IC705 power and
other circuits
NO
Check Q702 ( V.Buffer TR)
circuit
3-7