Why do I have sound but no picture

Lori Slotsky  sounds like a bad backlight. In a darkened room and the TV on a channel where you do hear sound, shine a flashlight beam at an angle against the screen. See if you can make out shapes or silhouettes. If so, it’s your backlight. Possibly a failed backlight strip or possibly the power board. You will have to remove the back cover from your TV and take a look at the boards. Better yet, post some good images of your boards with your QUESTION so that we can try to guide you some more.

iFixitでの質問に画像を追加する方法