Recently, my hi-fi has developed an intermittent fault. Somedays the right channel is around24-28db quieter than the left. Somedays it works fine.
The problem occurs with all the sources (cd/radio) and it also can be heard via the headphone socket.
Its a Bang and Olufsen Beocenter 2300 (the product list on this site does not list this model), which uses a datalink system to send the audio signals to the power amps in the speakers. Each cable carries the signal for both left and right channels, which are then selected via a switch on the back of the speaker. I have two datalink sockets on the stereo, and you can either use one cable per speaker or daisy chain the signal from a single socket to one speaker then onto the next speaker.
I have tested the cables with a multimeter, and all the relevant wires seem intact.
I did notice an strange occurence. I tried to unplug the working speaker whilst playing a cd, and suddenly the quiet one burst into life. Plug the other speaker in and it drops again.
I have downloaded the service manual for the unit, and i have a feeling it could be a pre-amp problem..although i am unsure which part of the pre-amp is likely to be at fault.
Can anyone suggest a logical plan of attack for testing a pre-amp circuit?
many thanks

Audio Players & Recorders - Bang and Olufsen - Beocenter 9300 Shelf System