Without knowing the make and model you could be having one of a few different problems . 1) you could have a loose connection in the set preventing the high voltage from turning 2) shorts in the horizontal deflection circuit preventing the high voltage from turning on 3) or something in the video circuit blanking causing no picture . If you have a sony tv some of these sets have had weak picture tubes . That can be costly . Wish i could have helped you more but not enough information . You can call a repair man to see what an estimate would cost to get it checked out . Good luck
James
November 2008
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