Beosound 9000 MK1 no standby led/like dead

[genesis]

Hello everybody 🙂

I just bought a faulty Beosound 9000 and I am trying to repair it. but i need help to understand how the beosound 9000 starts on power on.

Does it move the clamp or do something before turning on the standby LED?
As you may know, there are several microcontrollers inside which communicate together via the I2C bus.

the 5V is ok and I can see the I2C broadcast between the microcontrollers but I think the software is waiting for a position feedback from a sensor or something like that before turning on the other supplies like the 12v.

the relay does not turn on and the IC1 pin 12 stay to 0v (perhaps IC1 is faulty) because I think the 1st thing the link processor is doing is to turn on the power supply.

Thank you 🙂

edit: I think the link processor is dead.
its oscillator work, the reset line is released but it does nothing, don’t send data to the CD4094 (clock+data stay at “1”), no row scanning for the keyboard, and the main processor send I2C calls at address 30h but with no acknoweldge.
bad luck :/
I think it’s impossible to find the microcontroller firmware online unfortunately.

[genesis]

I was wrong, the 30h I2C call is made by the link processor to the main processor.

after more analysis, it’s the main processor the problem.
the CPU seem to be dead. no memory access (ram/prom etc) only the oscillator is working.  so I need to find a new one to replace it and make further tests.

[genesis]

and if you never seen what’s inside a beosound 9000 CPU box, here is the answer 😉
(removing the pins is not easy, the pads are very fragile)
(sorry I can’t remove the second attachement ^ ^)

[genesis]

I continue my monologue 😀
a new CPU is on the way.
In the meantime I checked the PROM of the code and it seems intact.

[Author]

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