This is the cheat code database which i know is the latest i got thats for the R4..So you can put this in the cheat code folder in your DSTT and activate away.Im positive you can find the cheat you've been looking for, for YuGiOh 2008.. Enjoy!
With schematics on the other hand; while it can be difficult to read through, you'll get the gist of things once you find which component is needed to be replaced.