Have a Philips 37PF7320A/37 lcd. Had picture no sound, then picture went. Can play dvds on tv, can hookup and view laptop on tv via hdmi but the only way to get a signal is by using the red/yellow/white analog connections from cable box. Tried plugging cable directly into tv-won't play. Cable does play when hooked into another tv. Help?

Jg541, May 2010