A simple thing to check is to see if the short is somewhere in the playfield, backbox or coin door. Just unplug all the Jones plugs and then power on the machine. If the fuse doesn't blow, then you know there's a problem somewhere in the playfield, backbox or coin door.
From your photos it shows one of the incoming power wires is attached to the 115 volt lug. If you're in Austria, you would be using 220-230 volts. Or are you attaching the power cord to a step down power adapter?
Also, it looks like someone added a wire to the transformer. That green and yellow wire with the plastic insulation doesn't look original.
Since we're kind of playing the guessing game here, please be extremely careful. I know 220-230 volts can be very nasty if you get shocked. Make sure the machine is unplugged from any power source when you are working on the transformer...