Having added a 5500 system to my ever growing collection, I have noticed a sudden loss to all sound comming out of the Left hand channels. SPK1, SPK2 and Headphones - irrespective of audio input.  Have switched speakers round - not a speaker issue

The line out channels are fine.

Any idea as to whether this is a capacitor issue or just loose solder ?

Well something has gone pop in the L power amplifier. You will need to track the signal.I would look for a burnt component or a crack in the solder. Check that both the metal loops are both there connecting the pre and power amplifiers though!

Faulty mute relay? (Try switching mute on and off several times)

As I understand it, neither SPK1 nor SPK2 or headphones produce any sound in the left channel, which
rules out the relay. The relay fault only affects SPK1.

It's very common to see lots of cracked solder joints in the connector bay.
It's also possible to flip the signal cable to the power amplifier left/right
to help diagnose but if you are not into servicing electronics, and particularly B&O,
I suggest you leave it to someone who is. It doesn't sound like a very costly repair.

Martin

Have done this (mute..mute...etc), no effect. There is definitely 'current' comming trough as there is a noticable chage in atmosphere when the speaker is plugged/un-plugged

POP IN L POWER AMP!!!

Could not see any visible blowouts or cracks in the solder, though I may be looking in the wrong place, can you point me to the right place. I suspect I will have to get an engineer to look at it if it is not a solder problem.

Martin,

which is the signal cable ? I have lots to choose from !