My toshiba 57 inch rear projection tv every once in awhile makes a loud pop similar to a spark noise and the screen either goes black or flickers. do you have any suggestions what is causing this??

THis could be one of the CRTs (Color Tubes) is bad or the high voltage is leaking somewhere.
Toshiba projection TVs have history of yoke problems.
My guess is one of the CRTs is arcing inside. This TV has 3 CRTs red, green and blue. Replacing a CRT is not easy or cheap to buy if you can find it. If you like this try calling a TV technician to track down the high voltage arcing. DO NOT TRY TO DO THIS BY YOURSELF.

Best of luck my friend.

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