BeoLab 8000: suddenly switches to Off while playing music

[KolfMAKER]

I have one BeoLab 8000 (serial nr. 1086 xxxx) with strange behavior.

My music source is connected via the RCA/Line input in the foot. The selector switch is set to  RCA/Line.

 

This is what happens:

• When I start playing music, it does not immediately switch to On. Only when I set the volume on my source quite loud (appr. 85%), the BeoLab switches from Standby to On.
• After having played music, but at a lower volume level then that made the BeoLab switch On, the BeoLab 8000 switches back to Standby/Off after appr. 35 seconds.
• When playing music on the same volume level as the level that made the BeoLab switch On, it keeps playing.

 

Question

• Anyone, any idea what could be wrong?

[auric]

The damping material has been known to degrade in Beolab 8000. Possible it has become conductive and shorting out some of the circuitry?

[KolfMAKER]

Thnx for responding and sharing your suggestion Auric.

Yes, I know about the foamrot issue. In this I did check all PCB’s, connectors, etc. for foamrot. Some copper traces have had a ‘by-pass’ already.

What bothers me is that at high volume/signal strength the Stand-by/On switching works well. But at low volume/signal strength it doesn’t.

Do you have any other suggestions?

[auric]

I don’t have any additional suggestions.

My original thought was that the residue from the foam could be creating a short or adding some resistance hence higher signal goes through. But if the PCBs are all clean the fault is somewhere else.

 

[Die_Bogener]

The copper traces of the BL8000 pcb are very thin. Acid of the foam does it’s job.

And when there are already a lot of “by-pass” repairs… ok, you will need some more.

There is not only the amplifier. There is also a round board in the foot with the LED. This board gets all the acid and debris of the foam…  and is always forgotten…

[KolfMAKER]

Thanks @Auric & @Die_Bogener

I think what I will do next is switch the PCB with the LED. I have one of a working BeoLab 8000 that I can try if that makes a difference.

[Author]

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