Hi Stefano,

it could be a number of things - it may not be the speaker that is the problem.  Are the Beolab 4000's daisychined from one Powerlink output or do the each come from their separate Output?  Have you checked the Powerlink cable into the one that is red?  If it isn't fully connected at either end it can cause a problem.  The pins in the Powerlink output of the Ouverture could be corroded from storage.  Try a bit of contact cleaner on the power link plug and move it in and out a bit.

Are you sure that the switches on the back of the BL4000 are set correctly - maybe it is accidentally switched to line?

If you swap the speaker with the green light with the second speaker, what happens?

Don't start playing about with things without checking these first.  They are the common problems - especially the cables.  Fuses don't tend to blow on these often - I think there are 3 in each speaker.  Unlikely to be the problem.  

Dave.

Dear Dave, I just came across this thread and am experiencing a similar problem.  I have had this pair of BL 4000 speakers and they are really wonderful.  A few years ago I changed my set-up and now just use them with Sonos through their line-in connection.  I am no longer using the Powerlink system.  It was working perfectly well until recently.  Now one of the two speakers sometimes does not kick in when I switch on the music and, more often, starts oscillating between on and off.  I don't know how the speaker switches itself on but that switch appears to be malfunctioning.  Any idea what the problem may be and how to resolve it?  They're great speakers and I'd really like to remedy this issue.  Thanks very much for your suggestions.

I smell foam rot.

MM

I switched the cables and the problem remains with the same speaker.  Milemissen, what do you mean with 'foam rotund what can be done about it?

Millemissen, I meant 'foam rot' before the autocorrect got to it...

Musiclover wrote:

Millemissen, I meant 'foam rot' before the autocorrect got to it...

There's a problem on older (Mk 1) BL4000 where some of the acoustic 'wadding' inside the speaker casing perishes over time and 'melts' onto the electronics, causing problems.  It's mentioned elsewhere on the forum.

EDIT: See Jeff's post three down on this page: /forum/general-discussion-and-questions/beolab-4000-vs-17

@Musiclover

Assuming that your BL4000 are 'older', this could be the reason.

You'll basicly recognize the 'older' ones by the on/off switch on the from where the red/green light is.

Not knowing whether this is the reason for your speaker misbehaving, I'd advice you to examine both speakers for the foam rot inside anyway.

More and more of these speakers suffers from this.

If you realize that the process is just starting, you can still save the speakers by removing the damp material and clean the electronic.

Even if this is not the reason yet, it is best to remove the damping material in order to prevent them for what probably would happen sooner or later - and not having to worry about this for the next many years.

MM

@Millemissen, Thanks for all the great inputs.  These are 1999 BL4000s.  The on-off oscillating is relatively recent.  I have opened the speaker up and the foam is indeed falling apart at any touch and is quite sticky.  I have removed it the best I can.  I have reassembled the speaker and now it won't get power at all, the red light doesn't even go on.  I can't see anything wrong, but clearly there is.  Any ideas?  Thanks very much.