Although I can't be certain, it seems to be coming from the front part of the receiver, somewhere behind the display panel.
The initial part of the 3-second "buzz" sounds similar to the "bing (?)" noise you hear when you turn on a plasma, then progresses into the buzz. It's hard to describe Again, everything functions normally - I can watch and listen to anything even during the "buzz" without a glitch. Please help! It's very frustrating, mainly b/c I've never even heard of this happening during my months of browsing this forum.
Edited by Gdell - 12/12/12 at 4:41pm