Hitachi 60CX29B TV "having poor picture quality playing" Questions

...having problems for about 6 months. First it started that the picture & sound would come on for awhile & then shut off. Intermittantly, the picture & sound would come on & go off-at first it nly ...

...to three different brands of TV. The picture was often "black screen" on a Toshiba, but was merely poor quality on the other two brands. I upgraded to a Sony KDL26M4000 from the Toshiba