I would definitely have a service technician come out and take a look at the unit. Loud buzzing noises are not considered "normal operation", tho some panels do have a slight hum that IS normal.
Better safe than sorry, I always say. Why not give our service department a call and schedule an inspection? 800-SAMSUNG is the number.
My a650 50" plasma is about ten days old, and it is making a loud buzzing noise some of the time. I run the cable box and the PS3 and TV through a new Sony Receiver (Sony STRDG720 7.1 Audio Video Receiver) and the buzzing noise is quite loud. It does not do it all the time, so I don't know what to do next. Is this an issue for anyone else? thank you