There isn't much information about the Mayumi v3 out there. From what I have read it seems to be an earlier version of the Mayumi v4. There must have been a bug or issue that caused the developers to erase it from the Internet. The code runs on PIC12C50x chips.
If you have any additional information about Mayumi v3 modchips please let me know. I'd like to fill in this page with more information.
- Coming soon.
PU-23 board diagram
I have no idea if this diagram works or not.