PPC 640 DD drei Signalton beim Booten

Maybe a problem with the video settings?
The DIP switch settings are:

SW1: Monitor select
ON=Internal Monitor, OFF=External Monitor

SW2: Video Emulation Mode:
ON=CGA, OFF=MDA

SW3: Internal Adapter
ON=Enable, OFF=Disable

SW4/5: Video Mode Init
ON/ON=MDA 80col
ON/OFF=CGA 80col
OFF/ON=CGA 40col
OFF/OFF=EGA/VGA (ext. card)

SW6: Not in use

So normally the switches should be ON/ON/ON/ON/OFF/X