Decided to region mod my GC but didn't like the idea of a switch.
I decided to use the reset button signal to activate a LM339n comparator to force the GC into NTSC-J as it seems there's only around 4 games that have the region issue and those are NTSC-J.
Kururin Squash: The main text is displayed in ASCII. However, game saves fine and is playable.
Donkey Konga 1-3: The games won't save. Game is playable.
Mr Drillier: Drill land: The games won't save. Game is playable.
F-ZERO GX (JP): Missing graphics, but there is a Action Replay code to fix problem.
Anyway, you region mod your GC to be JP then install this and whenever you power the system holding reset it will load the JP bios. Reset still functions correctly.
Id imagine it will be a pain to get working with JP multi cds titles as you cant really hold in reset when loading the next CD, and from what I read the system checks on every CD load.
https://www.youtube.com/watch?v=mlr5iF_VLp4
There is probably something similar to the lm339n in single channel much smaller but i haven't looked, its what i had.
