The pdf manual from Synthex has a diagram
http://www.megadrum.info/forums/download/file.php?id=1089This is my build:
All C-legs are tied together, NC-legs has their own as shown in the diagram. Don't let the extra red and black wire in the picture confuse you. It's for the LED.
And a design tip... if you don't like the big caps on the buttons, pull them off and color the pin to your liking. I put the LED in the middle.
