Model # PS-42D8C has no video on all inputs, but the screen is lit, as I can see it in the dark. Sound is very low on T.V. cable input. It does switch through all the inputs, but no signal, & when searching for the VGA input, it will find the input. Prima says replace the main board Part # 667-PHld8-01. Has anyone fixed this fault with this part? Prima says it's not a common problem, & seems to only be guessing about it! Have you guys seen the video processor board, or video boards cause this? Thanks, Dani.