Beocord 9000 – keypad not responding

[baek47]

I bought a Beocord 9000 and did various repair – but it is not responding at all activating buttons on the keypad panel.

I powers up and I and there is light in the dispay + cassette drawer.
All belts are changed and capstan is running.
All leafspring concats looks good.

I can meassure the -24, 24, 32, 13 volts on the board 6.
I can also meassure 6.2 and 5 volts on the board 1 – didnt check all testpoints here.

But looking at P21 wire 3 in the servicemanual it says 5.5 Vp and shows some kind of pulse or AC curve.
The P21 wire 3 only feed the IC1 (input/output expander) pin 38 texted 50/60hz.

Meassuring P21 wire 3 I have:
1,6v DC and 0,7v AC connected to the board 1
2,7 DC and 1,7v AC no load
My very bad usb oscilloscope shows nothing….

Could this be my problem?

Best regards baek47

[baek47]

I also recapped all brown/orange ROE capacitors.
I replace the 4.7v zener before the P21 wire 3.

[baek47]

I also recapped all brown/orange ROE capacitors.
I replaced the 4.7v zener before the P21 wire 3.

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