[KolfMAKER]

Thanks Keith!

I am away currently.

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

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[KolfMAKER]

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.

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[KolfMAKER]

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.

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[KolfMAKER]

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?

 

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[KolfMAKER]

@Keith

@Beobuddy

What do you think after my last measurements?

Suggestions welcome.

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[KolfMAKER]

I am working on a similar situation. Have a look at this thread. Hope it helps.

BeoLab 8000: dead / no red LED, measurements attached

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[KolfMAKER]

Thnx Beobuddy.
FYI, the multimeter I am using is a Voltcraft VC130-1.

So I measured between TR1 and GND/pin 2 on P2, while having power on the BeoLab 8000. So it’s in standby mode, red LED on. Here’s the results:

• TR1 Base <> Pin 2, P2 = 0 volts
• TR1 Collector <> Pin 2, P2 = 7,33 volts

 

What do you think BeoBuddy, what could be the underlying cause?

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[KolfMAKER]

Keith Saunders wrote:

The fact that the impedance of your meter was able to trigger the relay tends to mean that a component has gone out of tolerance rather than being totally faulty. Clarification Points
In your last post you said “I currently do not have equipment to connect via MasterLink” I am assuming you intended to say “Powerlink” rather than “Masterlink“?
Also you said “Plug 3, pin 1 <> pin 2 = 24 volts” which is excellent because that should have triggered the relay. Was the RED light on when you checked this?

• Ad. MasterLink > Yes, you are right. I meant of course PowerLink.
• Ad. Red light > Yes, the Red LED light was on at that moment.

Concerning the D1 diode Keith, can I just order a ‘1N 4148 diode SMD type’ ?

 

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[KolfMAKER]

Thanks a lot Keith!

Red LED is ON again

First of all, after my last checks I put the PSU/AMP-block back into the speaker casing, and connected everything back to original.
Surprisingly, the red LED went ON again! So that’s good. Obviously I also checked if it would respond to an audio signal, but unfortunately it doesn’t. (I checked, with RCA connection as I currently do not have equipment to connect via MasterLink)

 

Next checks

• TR3 Emitter <> Plug 2, pin 2 = + 15 volts
• TR4 Emitter <> Plug 2, pin 2 = – 15 volts
• Plug 3, pin 1 <> pin 2 = 24 volts

 

D1 check

I set my multi-meter to continuity/diode check and measured twice: once with the black probe on the top of D1 and the red probe on the bottom, and once vice versa. See the measurements in the picture below.

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.

I found that the D1 is a type 1N 4148 diode. So I probably need to look for this one as a SMD type.

Like to hear what you think Keith. Could this be the cause and is it just a matter of replacing it? Or could there still be another underlying cause?

 

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[KolfMAKER]

Thnx Keith!

I measured the voltage between pin 1 & 3 of P2 = 44 volts AC

Just to be sure, I also measured continuity:

• T2 pin 7 > plug 1, pin 1 = OK
• T2 pin 12 > plug 1, pin 3 = OK
• T2 pins 9 & 10 = OK

Knowing this, what do you think is wrong?

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[KolfMAKER]

Yes, I agree with the advise of @Kronzilla.

Refoaming is definitely the best option. Your speakers will sound like intended and be ready for many years of listening pleasure to come.

I have done several speaker driver refoamings. This link is to repair kits for Bang & Olufsen speakers:

https://www.repairyourspeakers.com/en/foam-rubber-surrounds/bang-olufsen/g-10000016

This link is reference material like video’s on how to repair:

https://www.repairyourspeakers.com/en/repair-videos/c-1

 

 

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[KolfMAKER]

I know there are different types of the BeoLab 8000. Most people talk about MK I and MK II. The MK II often described as having the ‘bass update’. BeoLab 8000 MK II has serial number 16992475 and up.

I have also been told that the BeoLab 8000 had an ‘ABL’ function form the first model onwards. But that it was changed with later versions.

I recognise three models: MK I, MK II and 8002. But I am also intresten to learn if there’s even a 4th model, and what others believe the differences are. So anyone, be invited to add your knowledge!

Concerning the Service Manual: as far as I know, there is only one Service Manual.

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[KolfMAKER]

What is your serial number?

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[KolfMAKER]

Yes, size will help. I think it will be smaller than I first thought. Especially because there is only one driver in the box.

The wooden casing looks like there should be a back panel.
The grey back panel looks more modern that the speaker and casing.
This speaker now makes me think of a loudspeaker that came with a record player with built-in amplifier.

1. Yes, please let me know the measurements.
2. By the way, where did you get this speaker / do you have any background info?

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[KolfMAKER]

Hi @Beo3000fan
Thanks for the extra pictures.

Can you do following?

• Make a picture of the backside-panel (the one you took away to see the inside)
• Let me know the measurements of the loudspeaker box (W x D xH)

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[KolfMAKER]

Thanks for sharing your idea Olivier!

The Grundig box 45 comes close, but is not the same. The speaker we are looking for has horizontal slits, instead of vertical.

Also, the front panel is completely integrated with the speaker casing. It does not look like it can be taken off to access the drivers. This looks different on the Grundig 45.

That’s why I think it is interesting to see the backside.

(Maybe, it is not a loudspeaker;-)

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[KolfMAKER]

@beo3000fan

• Can you share more pictures?
• Also one from the backside?
• Are there any labels visible?

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[KolfMAKER]

It looks a lot like one of the speakers in the Grundig line of ‘Grundig HiFi box Lautsprecher’. For instance the Grundig HiFi box 740:

https://www.radiomuseum.org/r/grundig_hifi_lautsprecher_box_740.html

But it probably is a different model. What I can say is that Grundig produced several speakers, with all wood front grilles. And with the slits horizontally. The 740 and 525 are examples of this design.

have a look over here:

http://www.hifi-wiki.de/index.php/grundig_box_525

This Wiki has an over of most grundig loudspeakers with specs and pictures.

By the way, most Grundig all wood loudspeakers with horizontal slits, were produced in 1970.

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[KolfMAKER]

Ah, I did not understand that you had the 5 volt connected most of the time.

I expected that you were mainly talking about the RCA connection between Sonos and BeoLab.

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[KolfMAKER]

Another suggestion for you, to make things easy.

If you keep the BeoLab 8000 in an upright position, then you can more or less ‘unfold’ the lower panel with the PSU and the Amp. So to speak; ‘turn it as a hinge’. (See picture)

If you work this way, the power- and the two JST-connectors will still be connected (via the bottom of the speaker casing). So the PCB’s will be powered as normal.

But also, you will have easy access to the trace-side of the PCB to do your measurements. Because it will be face up to you.

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