Tim, sounds to me like the backlight inverter is going out. You want to definitely check on fuses or continuity of voltage supply lines going to the X Board/s, (your case check the X Board) as well as the LVDS cable. Replace blown fuses, connect broken lines, and resolder loose solders. Check on the capacitors on your boards, they may be either loose or popped. Look for any leakage on the boards (looks like a oily sticky substance) and check the top of the capacitors. they should be flat. Any bulging indicates a failed capacitor, The older LG's have the backlight inverter power separate from the power supply, and in that case you will require a new LCD Panel. Very costly, if you can even find somebody who has them for sale. The newer LG's have the inverter connected to the power board. In that case you could try to fix it by replacing the power board. It would be great if besides the model number you could find the Chassis number. It might be possible to get a service manual for you and give you some more specific details for your TV. Hope this gets you started in the right direction. Good Luck.
I had the same problem but i have a DELL, i could not work out why suddenly the right side of the screen was all dark, then i thought the lightnings gone, then i thought its not the screen as all the pixels are still working behind it, so then i went to the older problem that when i was a kid it was common problem the power lead/cable, that is plugged into the back of the monitor, the fuse might of gone or something to do with the power not going right into the screen happened a lot 18 years ago but this is less common recently, so the power cable is not working right and thus creating a problem with the monitor just like when a power supply is old and is just hanging in there to keep your pc running while you upgrade parts inside the pc it will cut of so i changed the cable that powers the screen and it worked no more dark side, i can not explain why this happens, but ide suggest its a old problem with power leads or cables pluged in to what ever devise has to work right anyway thats how i got mine to fix simple get a new lead just that plug it in and turn it on i hope it was of help.
