Well – I made it so far, that when I disconnetc the P26 – the 8 pin plug on PCB 11 – the DAC, the autocalibration turns of after been engaged for about 10 seconds – which seems correct.
But why – I still dont know
I have tried to replace PCB 11 and 13, one at a tim, with PCBs from a working machine – without any changes ;-(