Hey, thanks for your help. I took a look at the cable and the 470 ohm resistor as well as the 220uF capacitor seem to be present on the csync line in the SCART head. So my setup obviously just doesn’t like the sync stripper. Which is a bummer, because otherwise the cable from thefoo.83 is really well made.
Well anyway, I’ll buy a cable from retrogamingcables.co.uk and see if that works better.