OK My grand-daughter has been (ab)using our microwave for some time and managed to get it into the state that you'd expect from any 17 year old. My wife hasn't been very happy about this for a while so decided we need a new one as it's now "disgusting". ( in the olden days women would clean things but... :-/ )
Anyhow, the final straw came when I attempted to use it's built in grill and filled the house with smoke. So I now find myself the owner of a nice bit of kit to play with and upon closer inspection I find that the interior is, in fact, metal and the (inner face at least) of the door is also made from glass. So obviously I'm planning on making this into an oven for all kinds of interesting stuff (reflow, molding plastic etc..).
I've already removed the magnetron and the high voltage stuff. (that may come in handy for my CO2 laser project I've been meaning to get around to building)
Inspecting the control board it seems like a very simple setup with a microcontroller at it's heart. After carefully removing the potting compound from the micro I find that it's a SH69P25K. Unfortunately a quick look through the datasheet reveals that this is a One Time Programmable device, so there's no chance of reprogramming the chip
Anyhow, it turns out that most of the pinout is fairly close to an atmega328. Both are 5V, 28 pin DIL and the Power, GND and oscillator connections are all in about the right place. (although the existing crystal is just 400K!)
So anyhow, I have the thing mostly cleaned up now, my intention is to remove the existing micro and replace it with a socketed atmega328. It'll probably take a bit of experimentation to get the display working, but I'm quite hopeful this could be an interesting little project.
If anyone else is interested I may post updates.