Why did my screen go black but has sound?
Screen went black can still hear sound
The LG 60LM6450 is a 60-inch LED television released in 2012. It supports 3D video with glasses at a resolution of 1920x1080 pixels.
If when shining a flashlight into the screen you still see things. It’s probably a backlight issue. LED’s often last a really long time. LED drivers and power supplies, not so much. The top three failure inducers are temperature, power surges, and cheap parts.
Also if the power light is blinking or odd colors the TV itself is trying to diagnose the problem for you!
this is a backlight issue. Now we need to determine if it is the power board, the main board or the actual backlight strips. LG has multiple issues with bad backlight strips. As the previous poster mentioned, the first test needs to be done in a darkened room. With the TV on and hearing the sound, shine a flashlight beam at an angle against the screen. See if you can make out shapes, silhouettes etc. If so than it is most likely your backlight strips. If not then it can be your main board or your T-con board. Let us know what you get.
Also, make sure that you try all different input sources. (HDMI, COAX, Composite etc., do not use a cable box alone. Try a DVD player or Game Console as well) Sometime cable boxes can do this as well. So you need to make sure that this is a TV issue alone.
After you checked all of this, you will have to remove the back cover from your TV. Check the boards for visible damaged components. Post some GOOD pictures with your QUESTION. That way we can see what you see.