Beolab 8000 Not going in to Standby?

[Robbie010]

Afternoon all.

Long time lurker here….. I’ve come across an issue while repairing my in-laws Beolab 8000’s. The internal damping was completely perished on both speakers and both had faults. After stripping them down, re-damping and thoroughly cleaning the PCB’s on both units they are now functioning fine and sounding great, however, one of the speakers refuses to go in to standby once the signal stops.

Can anyone suggest what may be the issue here?

Is there a particular section of the PCB that I need to be investigating?

Thanks.

[Robbie010]

Nobody!??

I’ve read all I can and searched threads but all the standby issues seem to centre around the speakers being dead after the standy trafo goes caput!

The speaker works fine, it just won’t switch off….. is this a relay issue?

[Dargo]

Hi Robbie,

I also have this issue with one of my 8000 speakers, it’s always active which makes it very annoying to always switch it off and on at the mains power.

I also cleaned all PCB’s and the column, installed new dampening material and no difference.

I had a feeling it might be PCB 06 Standby that was playing up so I even have redone the solder on that board with no success, capacitors and diodes seem fine.

Does anyone know where the problem might be? I’m a beginner at diagnosing and reading circuits. I am curious what part is responsible for the standby. I know when power link is not active it automatically shuts down and line usually turns off within a designated amount of time if no signal is active.

Any clues would be much appreciated. It’s the only thing wrong with this set of speakers and it is driving me crazy every time I work on it!

 

[Dargo]

FIXED IT!!

Ok so a few things I ran through. I opened up my correctly working 8000 to have on the side to measure values.

I checked the Relay first on the Transformer board first that I believe may be responsible for the two transformers switching and if you trace back to the PCB 2 the signal appears to be from power on/off section in the Block Diagram, I didn’t have a 24v supply with me so I tried swapping the relays over, no changes here.

Next I traced the wiring back to TR11 I found the connection fine but then I tested the transistor and comparing the reading to the working Beolabs PCB I found a bizarre reading on TR11! must be this little transistor! I took it off (broke the pad unfortunately so soldiered back on a new one) Ordered a new transistor (BC847B) you will find in the manual… and It’s standby now works!!  I ordered 5x of these transistors and replaced the working one in the working 8000 for good measure down the line!

I’m not sure if it will help you fix it but it’s worth checking that Transistor, it seems responsible to sending the signal to the relay and PCB 6 with the light!

[Author]

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