Check the foam in the speaker. If it is gray, it will have started to become a sticky mess that eats away traces at the amplifier section. This is a well-known problem - search in the old forum and you will find lots of info about it.

Open it and see if the PCB's has been affected by the black damping material. If so clean and repair the PCB's. If repairing ready or if no black damping material ( the series from about 2000 had new white damping foam ) then you will have to do some measurements with a multimeter. If you have one and still have a little knowledge of the subject, I can guide you further in de repair process, if not look for a local electronic hobby man or go to the Dealer. No sound actually means a power problem +/- 50 volt for the power amplifier. Do you hear the internal relais switching on any moment.

Thank you both for your replies. I will check the internal relais. As I aquired a newer pair of beolab 8000 I will disassemble the old pair to try what is possible to repair them. I will get back to you Leon for guiding me through the repair process if possible. If I get the one beolab back to live I would like to recap them. But this depends also on the in the units. Martin