I have an old Panasonic SA HT 700 that sometimes emits a high pitched whine,or no sound at all. Turning it off and on again seems to work, but how do I get this to just not happen?

SOURCE: High Pitch Sound From Samsung TXN3071WHF 30" TV

I think its the flyback and its starting to leak. this is a component responsible for the high voltage of your tv set. always observe safety in dealing with this. Have it check by a qualified technician. Good luck!

SOURCE: RCA 36" TV - High Pitch Sound - No Picture or Sound

check for high voltage s3ection of your TV. A Flyback transformer is defective especially in the high voltage cale of your flyback....

SOURCE: Alesis M1-Active left speaker emitts a very high pitched wine that sounds like feedback

have your built-in amp checked for trouble. there should be trouble in the output stage feedback loop. this is something to be done by a repair technician

SOURCE: Sony KF50we60 hdmi-dvi sound cuts when plugging into a ht-sf2300

DVI = HDMI without the audio connectors. So basically you need to connect your audio in some different way, PS3s allow you to keep your video signal as HDMI and change the Audio signal to component, so that is one way or doing it, not sure if the blue ray players allow you to do this though.

SOURCE: Toshiba Regza bought 1/28/08 makes squealing noise

It's in the repair shop. I'll write back what the problem was and how much it cost to ship.