You will have to clean off all the sticky stuff, check the fuses, If US type F3 and F4, if EU F5, if one or more fuses are gone, check the standby transformer

@Millemissen and @Soren Mexico.  Thanks so much for the advice.  I've extracted all the foam and cleaned the electronics carefully with some white spirit.  I've been testing the speakers for the past few days and they've been working perfectly.  They're great speakers.  Your advice was spot-on.  Thanks a lot!

Good job, you cleaned both speakers ? 😁

Musiclover wrote:

@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.

Hi "Musiclover"

I have just read this thread. I am a bit curious... on January the 28., You write that the speaker is dead, after removing the remains of the foam.
Then Søren tells you to clean off all the sticky remains of the foam - and on February the 4., you write that it is now working fine.
So - I would like to know: Did you only clean the Electronics, and then it worked?  - or was there any blown fuses?

Hi All

I am replying to this post because I got a similar problem for my BEOLAB 4000 - S/N 13063449 bought on bay some years ago and used once twice a year as it is in my summer apartment.

I checked the cables extensively and initially I thought they were the responsible , instead finally I was able to reproduce the behavior.

I I switched off the system and leave the BEOLAB in standby for some time it does not switch on. However if I disconnect the power (from the power cable) and plug it in again it works immediately.

If I switch on/off the system in few seconds it works without any problems.

I start thinking about capacitors, but I would appreciate your suggestion and maybe a similar experience.

Regards

The foam issue happens to the newer Beolab 4000's too. They changed the big pieces of foam to a better type but they still wrapped the cables in the same foam that deteriorates with age and damages the boards. The foam falls apart and sticks to everything causing a short and the board to fail.