Why does my Vizio TV intermittently have sound but no picture?

@tmat85 once the picture turns black and you still have sound, shine a flashlight at an angle against the screen. See if you can still make out shapes, silhouettes etc. This could be a failing backlight issue, as well as a bad power/main board. You would need to check the voltage from your power board to the backlight LED when the screen is lit and then against when the screen turns off. if you see a big difference it is most likely the power board. Again, you will need to check the voltages on BKLight on from the main board before and during failure to light up. Let us know what you find out.