Thank you for your detailed top panel repair and cleaning instructions. Glad that it works again!

Thank you T.W.G, I feel a little less alone 😁

There is something still bothering me and I would be grateful if someone could enlighten me.

There is like 13 keys on that top plate plus the circular slider. And hence, there is only 4 wires in the flat wire connecting it to the mainboard.
Do anyone know if there is some sort of "intelligence" below the thick plate or what kind of mysterious science helps to distinguish that button from that other one?

I would think its about resistance value due to the length of the tracks or something but I would find a poor design as pressing two buttons at the same time will drive the unit crazy and resistance will decrease with time (could make sense after all 😁).

Do anyone know more?

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Bonsoir matador43,

no, there isn't any intelligence (a bus or something else) anywhere inside the touchpanel.

The touch-panel is nothing more than a collection of resistors, which are building a voltage divider.

This analogue voltage is then read from the main controller's ADCs and then the software decides, which button is pressed.

For the volume control the touch-panel generates something like two phase-shifted triangular voltages, similar to two potis

connected (also mechanically) in the right way.

What I've written above is a bit simplified, but in general that's the way it works. Just 4 pins of the main-controller.

Two normal digital port pins and two ADC port pins. In addition one port pin as external interrupt input, when something

happened at the touch-panel.

After having trouble with my touch-panel two times I've thrown my BeoSound 3 in a corner and forget it for about 3 years.

Some weeks ago I got the idea to fix it and now I'm able to control it via a Beo 4. Never need to use the sucking touch-panel.

I've used an microcontroller with 2 DACs, which now generating the analogue voltages, originally made by the touch-panel's voltage-divider.

Yours sincerely

fK1G6HBzdnOY

Thank you for that explanation fK1G6HBzdnOY,

Would you have time to show us your BS3/Beo4 mod? It sounds very interesting?

All the best…

Hello matador43,

thank you for your interest. Because I'm very busy these days just two pictures. If you would like to have more details, please wait about 3 weeks.

Last work to do is to put the Nucleo board (STM32F446) into the BeoSound or if it's too big, designing a smaller PCB. I would share all the information I've got during this project including most of my source files.

Yours

fK1G6HBzdnOY

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Very exciting project, thank you for sharing it!

Of course take all the time you need, I'll be there waiting for details.

Amazing!

Hi fK1G6HBzdnOY,

Thank you for coming back and adding details on your mod.

That's very far away from my skills, knowledge and understanding but 8'm still admirative of your work.

You seems to know very well the guts from the BS3 so if I may I have a question for you: can you see a point where someone could add an aux. in?
Studying the schematics, there is two "tuner out" pins (L and R) and i wonder if you can inject aux. audio at those points. The purpose is to turn the BS3 as it is into a bluetooth or airplay speaker keeping most of the electronics. having it remote controlled by Beo 4/5/6 would be a great plus.

So far my BS3 work and I don't want to change it, but I know that it will eventually stop working and then I'd like to give him a second life.

Thank you.

Hi matador43,

from my point of view a good point for injecting an additional audio signal (e.g.: AUX) would be the analogue multiplexer 4052.

I've marked it red in the following picture.

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This IC has the analogue inputs from the mp3 decoder and the tuner and the main controller decides, which of them will be connected to the output.

The IC supports up to 4 inputs and from my actual knowledge only two are in use but at this point I'm not interested in doing it on my own. If someone would like to do it I will share the things I've reengineered.

Yours
fK1G6HBzdnOY

fK1G6HBzdnOY wrote:

If someone would like to do it I will share the things I've reengineered.

Hi fK1G6HBzdnOY,

Well, right now I will not since my BS3 is working nicely so far. But I know it will eventually fail again someday and then, I hope I'll find you!

I guess it will not be as simple as just connecting three wires to the third input and it will need some electronics to select that input right?

But hey, it opens new doors! Thank you!