If you’ve got an NTSC Super Nintendo Entertainment System then it’s very easy to modify it to play both American and Japanese Super Famicom games. Open up the cartridge slot doors and look for the small rectangular cartridge tabs, all you need to do is remove them. Combine this with fitting a SuperCIC mod, and you’ve got the most compatible SNES you can get.
Ideally you should take your console apart using a Gamebit, some people use a soldering iron to melt the tabs away without taking the console to pieces, or ripping them off with a pair of pliers – you would need a very steady hand to do this and you could very easily damage your console so it’s not recommended.
With your console unplugged, make sure you switch it on to discharge it, you should see the power LED flash quickly. Once you’ve removed all the Gamebit screws, then remove the upper half of the case. Then remove the screws on the underside of the lid and the spring for the reset button, you can then remove the the inner part of the cartridge slot. I simply used a strong pair of pliers to break the tabs and if necessary, a craft knife/scalpel to tidy it up.
Re-assemble and away you go! You can now fit Japanese Super Famicom cartridges in and play them straight away with no other modifications, check out some of the other guides if you want to pay PAL games.
I can’t remember where I first read about this, but it’s widely documented elsewhere on the web.