Tips on troubleshooting board PCB

[Mitb]

Wow, I put this project on the shelf for almost 2 years before I pulled it back out.

Ok, so I disconnected the coil on the board in question. I hooked it back into power and I am still getting the smell. Also I noticed the diode on the back is warm. Perhaps I need to order a complete set of all the components for this board and just replacement them? Is there a way I can isolate the problem without running it through 12v?

[Tony]

I've lost the place a little too

So there are currently no coils fitted, the diode you mention sounds like the 14V overvoltage zener. Is it at one edge of the board opposite the ferrite?. If so and you're supplying 12V it's faulty, just remove it for now if your power supply is stable.