@Keith

@Beobuddy

What do you think after my last measurements?

Suggestions welcome.

Update

The problem with the BeoLab 8000, not switching from stand-by to On (red to green LED), still persists.

PowerLink test
Since I temporarily have a BeoSound 9000 at hand, I decided to test the BeoLab 8000 on its PowerLink connection.

Result
When connected via PowerLink, this BeoLab 8000 switches smoothly from stand-by to On. So this works in normal operation.

Question
I assume, there is something wrong with the auto-start and RCA combination.
Please advise, what I can do next?

 

Thanks Keith, have a safe trip! Reading back, I noticed you mentioned this:

The negative end (plug 3 pin 1) of the D1 diode is directly driven from the “Auto Start” circuit which takes your source input on the RCA socket. You could therefore also test between plug 3 pin 1 and plug 1 pin 2.

And I did not measure that yet. So here's about that:

• I measured between the two pins as marked in the picture below.
• The measured value is 52 volts.

Hope you have a recommendation for a next step. Login to view image

I have gone back again and reviewed everything that has been done to date. A couple of questions came up:-

1. When you use the multi-meter which triggered the relay and you heard music, did the LED go green?
2. In the last post where you measured 52 volts was that with signal connected to the RCA socket?

It is clear that the problem is in the auto-start circuit and nothing to do with the relay circuit area. Going back to where you were testing at D1 you said:-

• Interestingly, with the red probe on the top and the black on the bottom: the relay clicks, the Amp turns on and music can be heard coming from the speakers.

Can you please go back and see if you can reproduce this situation. Login to view image

Thnx Keith!

Here's a response to all things you mentioned.

(1)
When you use the multi-meter which triggered the relay and you heard music, did the LED go green?

Yes, the LED goes green, and the speaker plays music.

(2)
In the last post where you measured 52 volts was that with signal connected to the RCA socket?

Yes, it measures 52 volts when a (playing) audio signal is connected to the RCA socket.
Though, it also measures 52 volts when nothing is connected to the RCA socket.

Curious to hear what you think of this.

Ernst,

Thank you for your feedback and I have to say it is a difficult problem to understanding based on the information we have to date.

Having said that the basic circuit operates otherwise the system would not trigger with the impedance of your multimeter. This leads me to think that we have a high resistance or open ground connection within the auto start circuit.

At the start of this thread you did mention that the unit was dead with no red light and after you put everything back together you got the red light meaning there was some connection made which was previously not made.

I suggest you check all the ground connections that use plug and socket connections particular associated with the auto start circuit. With the power off and your meter set to resistance connect one meter lead to plug 7 pin 2 as shown below and then check all other ground points have a connection i.e. no resistance.

Login to view image

Thanks Keith!

I am away currently.

When I am back, I will continue making your suggested checks.

Thanks again Keith. Very much appreciated you are still willing to help me! After having returned from abroad after a few weeks, I have immediately started testing what you suggested in your last message. I listed 7 components from your suggestion and picture, to be tested on a GND connection with the multi meter: TR9, R84, TR11, R81, C47, C65, TR7, TR8. I used the visual layout of the board in the service manual (see top part of picture below), to find the exact location of these components.   Here's the results First of all I could find TR9, R84 and TR11. Their location according to the visual layout in the Service manual and the PCB itself, was identical. These are the findings on these components:

• P7-2 <> TR9 Emitter = Yes, continuity
• P7-2 <> R84 = Yes, continuity
• P702 <> TR11 Emitter = No continuity on the Emitter, but Yes continuity on the Collector

With the other 4 components I found out that the visual layout from the service manual, and the actual layout of the board differ. So for them I am unsure what their location on the board is. In the picture below you will see both layouts. In the top image I have marked the 4 components that I can't match with the layout of the PCB. In the bottom image I have marked the 3 components I could find and which I tested. Speaker info

• Type number = 6801 (B)
• Serial number = 1448 8372

Comments / questions Maybe the results of the 3 tested components already give you a clue. Is TR11 malfunctioning and the cause? What do you suggest?   Login to view image  

I also got a pair of BL8000 with no signs of life (no light, no relay click). Really hoped for some busted traces because of foam rot, but continuity looks fine. On T2 I measured 230V, but no 44V or 22V. Instead I got 10V and 14V. Can I assume that the standby transformer  is gone?

Thank you for your help