For a long time, a mystery of the new style SNES was how to mod it to install a 50/60Hz switch. Well, that mystery has been solved. On the gamesx forum, this clever fellow was able to identify the pin you need to lift and modify to switch between the two speeds. To switch to the other speed, you will need a second clock crystal running at the appropriate speed and switch them with the CPU switch. Here it is:
http://nfg.2y.net/forum/index.php?showtopic=916
The requirement of a second clock crystal is interesting. I believe this may be a PAL only requirement because the faster NTSC clock crystal can be stepped down to PAL speeds, but the opposite is not true. The well-known older modification required no extra clock. Perhaps a bit more experimentation is needed.
http://nfg.2y.net/forum/index.php?showtopic=916
The requirement of a second clock crystal is interesting. I believe this may be a PAL only requirement because the faster NTSC clock crystal can be stepped down to PAL speeds, but the opposite is not true. The well-known older modification required no extra clock. Perhaps a bit more experimentation is needed.