This sounds like you have bad capacitors on the power supply board. Look for bulging capacitors. Any weak capacitors will have a bulge at the top. If you know how flourescent lighting works with a ballast, tv's work the same way to power up the backlights but use capacitors. The backlights when lit allows you to see the picture. If they are not charging up fully you get a black screen or a very dim screen which looks black under normal lighting conditions. Sometimes you can turn off all lights and maybe see a faint picture.
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This sounds like you have bad capacitors on the power supply board. Look for bulging capacitors. Any weak capacitors will have a bulge at the top. If you know how flourescent lighting works with a ballast, tv's work the same way to power up the backlights but use capacitors. The backlights when lit allows you to see the picture. If they are not charging up fully you get a black screen or a very dim screen which looks black under normal lighting conditions. Sometimes you can turn off all lights and maybe see a faint picture.