How to Modify a Genesis Model 3 to Play Japanese Games

Picture of How to Modify a Genesis Model 3 to Play Japanese Games
I recently picked up a Genesis 3. If you haven’t seen one, they’re very small versions of the Genesis. I later found out that they can apparently play Japanese imports. The cartridge slot is even wide enough to accomodate the larger Japanese cartridges, unlike the original and second generation versions of the Genesis (you have to widen their slots with a dremel or file). So I picked up a copy of Phantasy Star II on eBay to give it a try.

It turns out that it’s only partially true. It will supposedly play Japanese imports which do not have an internal region lockout. It appears that Phantasy Star II does have that lockout, because after the initial Sega copyright screen, it just gave me a black screen.This was not a big deal. I don’t know of any Japanese Mega Drive (the Genesis was called the Mega Drive outside the U.S., or rather, the Mega Drive was called the Genesis in the U.S.) games that I desperately want to play. Still, I thought it would be fun to try to get it working. And besides, Phantasy Star II cost me like $8, and that’s enough to buy a decent sandwich. And I can’t eat a Phantasy Star II cartridge. Believe me, I tried (note to self: try adding more cumin next time).

I gathered information on this mod from a number of places. Unfortunately, most of the instructions I’ve found have been pretty light on details. And since there are instructables for Genesis models 1 & 2, but not 3, I thought I’d condense what I found out here, accompanied by some pretty pictures.

So let’s mod a Genesis 3!


Step 1: What You’ll Need

Picture of What You'll Need
You will need:

  • 1 Sega Genesis 3. Obviously.
  • 1 or more Japanese Mega Drive games. Again, obviously.
  • 1 Phillips head screwdriver.
  • Tweezers.
  • Soldering Iron. I used a 25W one. You don’t want to use one that’s too hot here.
  • Thin wire. I used IDE ribbon cable.


  • SPDT Switch. I didn’t need one, which surprised me. I’ll get to that later.

Guide made by fwonkas.


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