Sega pads again

[psxphill]

I know this has done before, but I can't find a definitive thread, and I don't feel like blowing a CIA chip - Will 6 button Genesis gamepads work without any mods on an Amiga?

You should swap pins 5 & 7. If you don't and anything goes wrong then you'll kick yourself. Plus you can't get more than 2 buttons + the dpad working if you don't do this.
 
An adapter is easy to make, just pop to maplin and buy a male & female 9 pin connector, 2 x hoods + a wire. You can get them cheaper online though.

[psxphill]

This is just what I was worried about. Pin #7 is the 5Vdc, pin #5 is listed as potX (or not used?). If one pot line needs to be changed, why not both pot lines?

pin#7 for the megadrive is the multiplexor input
pin#5 for the megadrive is 5v.
 
So if you just plug it in, it will be drawing 5v from potx and the multiplexor input can't be changed. By swapping the pins and configuring potx as an output you can access all the buttons, as long as the game was designed to do so.
 
the poty line is used for an input (IIRC it's the right mouse button line). I think this is what causes problems on the c64 with blown CIA's, however I haven't had any problems on the Amiga.