You need a service manual. In some states there is a "right to repair" law but sometimes there is no service manual and you have to use sites like http://www.shopjimmy.com/tv-repair-tips to make your best guess which board to change out.
I've yet to find any techs tell folk which board to change. They can't because the set isn't on the bench with the usual service manual, test gear and spares.
Our LED LG TV 42ls345t started behave weird. After some time it is turned on (sometime few minutes, sometime a hour or so) it stops responding to remote control and will not show any OSD information. The TV registers the remote by flashing red light when remote is pressed, but only volume and channels up and down works but no OSD infos. Even tried secondary brand new remote, still the same behaviour.
When TV stop responding then it eventually turns off itself and is completely dead until disconnected from power supply completely and then it comes on again normally. Later the behaviour starts all over again after while. This weird behaviour happens only on arial/cable TV source. When I use USB source, it is fine.
Can anyone help what part/circuit board of the tv is bad or does enyone experience the same behaviour? Is there a simple fix to it?
I only found comments with similar problem on SAMSUNG tv but they have different components inside from LG.