I did the Gamecube audio mod as listed on http://gamesx.com/wiki/doku.php?id=av:nintendogcda but I internalized the mod. I'll update the wiki. Looking for any feedback, before I update though.
I built a small PCB and sent it off to osh park:
BOM from DigiKey:
1x Hex Convertor - 296-8208-1-ND
1x 12.288 Crystal - CTX266CT-ND
1x 47uf Cap - PCE3875CT-ND
3x .1uf Cap - 490-1532-1-ND
1x TC9231N - Obselete part, Find on Ebay/Aliexpress etc.
1x TX178A - Ebay etc. Really any 5v TX Toslink should work.
I'm using some small components in this build 0603 caps and TSSOP hex
Here is our hookup locations. This is my personal gamecube, I plan on doing the HDMI setup soon, (I'm building a new board based on the shuriken design), which is why I soldered directly to the SMD. I wanted to test on my equipment before the customers. You can trace the wires I soldered to the SMD to the Digital A/V pins. Which would be much easier solder. They pin numbers I think 22,21,19
Here is the case modifications:
I'm using Strong 3M double sticky foam to hold the board. in place. I would mount it in side the metal cage but the 47uf cap was too tall :-(