AP wrote:

Just got a Sherwood receiver (DAS RX-206ORDS) - quite nice, sounds
excellent - flawless - until it's been playing for around 45 mins, at
which point a buzzing begins inside the box. It's loud enough to be
annoying. Seems to be very localised - this is a ten year old beastie, all
bits & bobs rather than circuit boards - and my instinct is that it's one
component in there that's gone dodgy. Might it be worth repairing? Is it
something I could do, with a bit of common sense and a soldering iron? Or
is it landfill time? (I don't want to waste time & money on it, but it
goes against the grain to just junk something that's basically very good
and, apart from this one glitch, totally sound. Any help/advice
appreciated.)

It sounds to me like as something heats up it starts to draw excessive
current which is causing the mains transformer to buzz with the extra load.
Can you locate the source of the buzz?

Ian