LG 42LA86 Series Service Manual page 110

Standard Repair Process Detail Technical Manual
Error
Established
A. Video error_Video error, video lag/stop
2012. 12 .06
symptom
date
LCD TV
Revised
TUNER input signal strength checking method
Content A6
date
<ALL MODELS>
MENU  support  signal test
 select channel
When the signal is strong, use the
attenuator (-10dB, -15dB, -20dB etc.)