Hi, can anyone help me. I have a Beocenter 2800 and a 1800, both have the same problem. when the mono button is pressed both speakers work fine, when released only one channel works properly, the other is very quiet. I believe it could be the caps (the small red ones?)

Is it the same with all sources? If so, it is an amplifier problem. Could be the capacitors or maybe the output transistors. You need to do some testing! I note the service manual for the 1800 is not on site - I will remedy this this weekend.

thanks

As promised, manual now scanned and uploaded.