Hello, I tried something more: Under <Signals> there is an additional possiibility to generate signals: <Visible Signal> Mark Visible signal and take either <invert screen> or < light up screen > with the choice of colour. Acoustic signals can either used together or separately. On o.S.13.2 the signals are successfully working, on Leap 42.1 they are not. My conclusion is that it is not a problem of the audio system as it firstly seemed to be. Ebkr