Plasma TVs use flat-panel screen technology that involves tiny cells that emit noble gases between two panes of glass. The gases are turned into a plasma electronically once inside the panes. Plasma TVs can crack or scratch easily, but as long as there is no plasma dripping from the TV or any effect on the television picture, it's safe to fix a plasma TV screen yourself.
Turn on the TV. If the TV doesn't turn on, if you feel a wetness around the crack in the screen or if the picture isn't coming in properly, do not attempt to fix the TV yourself. Take it to a professional.
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Turn the screen off and unplug the TV if the TV appears to be in working order except for the crack.
Apply a thick coat of petroleum jelly to the crack. Rub it in slowly and thoroughly with a clean eyeglasses cloth.
Reapply the petroleum jelly and rub off again, if necessary.