Essentially, the 8 contact pins in the middle of the card on the US and the Japanese cards are switched. So all that a mod or a converter will do is "unswitch" those contacts. That is, your system wants to read the the pins on the card in 1-2-3-4-5-6-7-8 order, the Japanese card is set up in a 8-7-6-5-4-3-2-1 order:
US chips also check to see something else that's only present in US systems, so in addition to the above, Japanese systems also need to ground pin 29 of one of the IC chips on the main board, but since I believe you have a US system, this second issue is a moot point for you.
Topic: What exactly is the region lockout for the Turbo? (Read 515 times)
