Probably missing something here and could do with someones help. Old skybox malfunctioned. a kind friend, donated, a second Hand Sony VTX-S750U. Made connections in normal way, via Yamaha AV amp (nothing special but works). Digibox signal is fine as sound is being received which plays through amp but no picture to the TV. Checked cables to TV by connecting a DVD player, that is fine. Replaced the Digibox with a second hand purchase (same brand and model) from Ebay and exactly the same issue... sound but no picture. Am I missing something. Do I need to setup by pressing a combinations of buttons?? Confused. Any help would be appreciated.