Update2: The black screen is caused by setting jumper CS1, CS2 or CS12 on the eprom-cartridge-pcb (8 bit manshed).
These jumpers work fine with e.g. MSX-1 Sony HB 75 but with the Sakhr AX-370 they have to be removed.
Uridium and also YRM-504 FM Music Macro Cartridges work fine now, but alas: YRM-504 does not work in combination with the Yamaha SFG-05 module, resulting in a frozen screen instead after entering the BASIC entry screen.
:-(
