I have a Samsung PN63B590T5FXZA and there is a loud buzzing sound from the lower left (looking at it from the front). A tech came out three times and they can't figure it out. It's right near the plug, and they replaced the board and ps.
It is louder when it renders bright images (especially a white screen), and if I put pressure on the spot it dampens the sound.
I tried searching and I saw older SS plasma's that needed the following:
Install a felt cushion, Samsung part number is: AA63-60122L. The cushion will fill the gap to provide insulation between the FPC cables and rear panel.