Is the glass in the lower keyboard panel loose?  It can come unstuck from the plastic surrounds and lift slightly - this means that the sensor do not quite reach the underside of the panel.  There's is lots about this issue on the old forum, and discussion about how best to re-stick the glass to the plastic.

Do you have the service manual?

 

Thank you for your quick response

Yes, I know this problem with glasses, but this is an electronic problem.

I removed the glass the one that allows me to touch the plastic tips directly with my finger, but no effect!

I did some measurements on the PCB 5V and 7V are OK. The integrated circuits are powered =>OK The fault being on the 3 PCBs (left, middle, right), I noticed on the electronic diagram that there was a common wire to the 3 PCBs. It is the wire marked I28 which supplies the 4 circuits IC1 IC2 IC3 IC4 on the “S” input of the CD4044 and MM5450. But I have no idea on which logic level (+5V or 0v I should find) Any idea?

link

Thank you for your quick response Yes, I know this problem with glasses, but this is an electronic problem. I removed the glass the one that allows me to touch the plastic tips directly with my finger, but no effect! I did some measurements on the PCB 5V and 7V are OK. The integrated circuits are powered =>OK The fault being on the 3 PCBs (left, middle, right), I noticed on the electronic diagram that there was a common wire to the 3 PCBs. It is the wire marked I28 which supplies the 4 circuits IC1 IC2 IC3 IC4 on the “S” input of the CD4044 and MM5450. But I have no idea on which logic level (+5V or 0v I should find) Any idea?

I took the liberty of google translating your response into English! I am unable to delve too deep into the circuitry, but BC9500 probelms are often caused by bad connectors between boards. This thread is a good example - sadly the pictures are missing but I think you will be able to work out what is being discussed):  /forum/imported-unmapped/beocenter-9500-some-leds-and-buttons-not-working

It is possible to remove the glass panel ... 1 bolt on the side. It's a push and lift construktion...

... and then you see the rubber contact to the glass panel. Or is it missing? Touch and start.

Never touch the glass inside... NEVER!

Hello

According to the MM5450 datasheet, it seems that the signal sent to pin 21 (clock) must be 5V at 500Khz.
Can someone confirm these values by measuring on their BOCENTER 9500?

Hi

Sounds like there is a voltage missing somewhere....

Did you check 5 Volt direct on board 42 IC 3 Pin 20, IC2 Pin 16 and IC1 Pin 16?

If you provide an oszilloscope you could measure the CLP signal (Clock Pulse)

which comes from board 40 IC4 Pin 32.

This signal serves several boadrs with the CLP signal.

There should be a straight connection between P52-3 (Board 40) to P63-10 on board 42.

This connection goes straight to IC3 (M5450).

Check onnection for Disp.Data from board 40 P52-2 to board 42 P63-11. to IC 3 Pin 22

Check Key Enable from board 40 P52-6 to board 42 P63-7 (should be low?) to IC 2 Pin 5

BUT:

The MM5450 is just a LED driver IC.

The keys are driven by IC 1, 2 and 4.

Maybe there is a connection lost between board 40 IC 1 Pin 5, 6, 7, 8 via P52- 7, 8,9,10

to board 42 P63- 3, 4, 5, 6 to IC4 Pin 1, 9, 10, 13.

Here to check 5 volt IC 4 on Pin 16

Regards

Christian

Hello

Thank you Spassmaker  for this very precise technical informations
I will check it all !
Yes the MM5450 manages the LEDs but as the clock signal (pin 21) is also sent to the S/ inputs of IC1, 2 4 and I did not know what I had to find as a signal, it is thanks to the MM5450 datasheet that i now know what i need to find on this wire (500khz)

Hello,
I checked all the points mentioned
Here is the result of the checks

5 Volt on board 42 IC1 , 2, 3, 4 (5V clean =>no noise)

CLP signal seems OK: square signal but in the form of a "frame" no continuous signal => is this normal? => see picture Clock signal

Connection between P52-3 (Board 40) to P63-10 on board 42: OK

Check connection for Disp.Data from board 40 P52-2 to board 42 P63-11. to IC 3 Pin 22 : See picture (1)

Check Key Enable from board 40 P52-6 to board 42 P63-7: see picture (2)

Connection between board 40 IC 1 Pin 5, 6, 7, 8 via P52- 7, 8,9,10 to board 42 P63- 3, 4, 5, 6 to IC4 Pin 1, 9, 10, 13. : see picture (3)

Check 5 volt IC 4 on Pin 16: OK