40" lcd 1080p. buzzing noise

Question

when the screen is blank when turning over or screen is black there is a wasp type buzz coming from the components at the back(not the speakers)its not loud and disappears when the screen is not black.

are these tvs supposed to make this noise.

please only answer if you know your stuff thanks in advance.

Answer 1

That may a transformer noise. It may arise because an LCD draws the most power when displaying an all-black image, the opposite of a CRT. This means the power transformer works the hardest during pitch-dark video passages.

Transformer buzz isn't great, but assuming its rather quiet, is an electromechanical reality in economical or to-the-edge designs.