Below is a document on how to convert your Megadrive into a multi standard machine.
All modifications are at your own risk. I will not be held responsable for any damage / injuries caused by the use of this modification.
Ideally you should be competant with a soldering iron as the modifications require some delecate soldering to jumpers on the PCB.
This page was constructed entirely on Amiga
The document below details the modifications to add a language switch and 50 - 60Hz switch to your Sega Megadrive / Genesis.
Please note that the information is taken from the Video Games FAQ at rtfm.mit.edu. I strongly advise you to obtain a copy of this (it is in 3 parts) as it contains a lot of useful information about all systems.
If you have any problems / require more info email Mark.