Picture won't stay on. Sound is alright?

We were given a "36-40" Sony Trinitron TV. some months ago. It has sound but we lost the picture after our cable service had a problem. After it was restored about a hour later, the picture now won't stay on for lno longer than 5 to 10 minutes then it goes black. So, I need the TV. for my ill husband, that this has been entertaining for him while I'm away all day. We don't have much extra money, for high cost repairs, so I do hope that it would not be to expensive to repair.