My 1998 Trinitron, KV-27V22, went black.

My 1998 Trinitron, KV-27V22, went black. Occasionally when you turn it on, the picture will come on for about 15 secs, then go to a distorted half screen for a few more secs and then black. I have tried to adjust the "screen" screw under the back panel and unplugged over night for a hard reset but this has not worked. I am afraid there is some power issue but I need help to diagnose. Thanks,
Dave