If only the picture is out, and audio is normal, the fault is with its back-light inverter board. If both picture and sound is absent, and the standby light is ON, the fault is with its main board. If set is fully dead; even there is no standby light at all; the fault is with its main power regulator [SMPS] board. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/