I've searched through the forum for threads regarding the buzzing issue for plasma TV's, specifically Panasonic, but haven't found much info on people getting their issue resolved. I know many have had issues, but it seems they consider it somewhat normal and decide to live with it?

I bought the 42" PX77U plasma around 3 months back. It has been performing great with no buzzing noise issue until about a week ago. There was some buzzing noise that I could hear before, but that was only if I would stick my head behind the TV with the volume basically at 0. Not audible at more than 1-2' away. However, around a week ago, I noticed a high pitched buzzing sound emanating from the panel. I can hear it 10-15 feet away while the volume is on normal listening level. It's not coming from the speakers, nor do I think it is related to the brightness of image being displayed since the noise stays on even when I turn the TV off ! Although it the buzz is reduced with the TV switched off, ,but I got no noise with TV switched off during the first 3 months. It does go away sometimes after the TV has been on for more than 30 minutes, but I havn't been able to test it out that much yet. I'm thinking it is power supply related since the buzzing seems to be coming from that general area behind the panel.

Any input is appreciated, Thanks!

Sure it isn't one of the cooling fans going bad? My 42PZ77U has four of them along the top of the back panel and as a computer hardware specialist I will immediately know if one them pops a bearing or otherwise wears out. If the buzzing comes from the area where power plug is located then you are probably correct about the power supply..

The buzzing while off is a n/c feature of Panasonic

I believe the PX77 does not have fans but I can't find that information on the panasonic website. Last night I was watching TV and around 45 minutes later the noise went away completely. I'll keep an eye on it the next few days.