Sony Str Av1020 Buzzing
G'day from south australia,
I have had a sony str av1020 for a number of years. The amp developed a buz or hum that appeared and disappeared on and off for ages. I eventually removed the cover and found that apart from a few dry solder joints the main problem was a loose screw holding the circuit board to the frame. So.....try carefully tightening all the screws you can find around the circuit board. Good luck. It's a great amp.
Mike