I had to share this because it's just too bizzare, and I've seen nothing about this problem on your message boards.
I have a Sharp 26 inch television (made in 1993 Model # 25E-M40 Serial 311993) and a few days ago, it started emmitting a low hum from its speakers, and playing some radio station. After that it would all of a sudden lose picture and sound from the TV (the hum and radio would still play). I've tried unpluging the DVD, PS2, VCR, and removed and replaced the cable box, and nothing really helped. The only way to make the noise stop is to turn off the tv. What in the world could have caused this?
Well, the FM band of radio is sandwiched between VHF channels 5 & 6. Besides that I have no idea.
The main tuner or the PLL control circuit is bad.. I have seen this in a few sets and like I said most of the time you must replace the tuner. If the set is a 1993 model, most likly, im sorry to say, its not going to be worth repairing. Good Luck and please let us know how you made out.