The screen periodically goes black once very couple of weeks.

will serio  right now it reads as if you are saying you have sound but no picture. If so, in a darkened room shine a flashlight beam at an angle against the screen. If you can make out shapes, silhouettes etc, you know you have a failed backlight. That could be a bad power board or bad backlight strips. If you cannot make out anything with the flashlight test then it is possible that this is a mainboard, power board or T-con board error. We would need to see the boards so post some GOOD pictures of those with your QUESTION. Also, verify that your TV is a LG 60LM6450 60inch Full HD 3D LED Television

在已经存在的问题里加入图片