I found some pictures from the year 2000, where I modded a Genesis 3 VideoGame.
Here you can see the pictures of the Genesis 3
After opening
here you can see the Sega IC 315-6123
here you can see the „default“ US jumper settings
After removing the jumpers:
Technical Infos:
Pin 197: (USA/JAPAN)
If you shortcut R22 = 5V to Pin 197 -> Europe-/US-Mode
If you shortcut R24 = GND to Pin 197 -> Japan-Mode
Pin 200: (50/60Hz)
If you shortcut R25 = GND to Pin 200 -> 50Hz
If you shortcut R22 = 5V to Pin 200 -> 60Hz
Have FUN!
I will do a switchless MOD, if I get the next Genesis 3 for Modding