I have 2 Minimigs both fitted with the replacement ARM Controller boards.
In a recent cock-up I nearly managed to destroy one of the ARM boards by breaking a pin off whilst hastily pulling it out of the Minimig.
Thanks to a $1 DIP socket I managed to save the controller by soldering the pin back onto the board.... and gently plugging the controller into the new socket:
Which thankfully worked pretty well. During this whole debacle I happened to have a proper look at the mcu on the board and saw that it was an AT91SAM7S256. I remembered that I had a cheap dev board with the same chip on it. The dev board cost me $25 when I bought it, as opposed to the near $100 price tag of the ARM Controller, so I began to wonder if it might serve as a cheap replacement.
After some very careful pin mapping and buzzing the dev board out, I came up with this:
And it works 100% (or seems to so far). Whilst the board I used does not seem to be for sale any more, there are alternatives available and even this board ($27 on eBay as of this post) :
(the bigger brother AT91SAM7S512) should be simple enough to wire up and port the code to (if even necessary).
All in all a fairly cost effective hack that also has the benefit of providing JTAG access for devs that wish to extend the ARM Controller firmware.