Firstly monitor the serial output from the PIC during boot and paste it here (use a serial terminal application at 115200baud 8N1 and the serial jumper on MCU IIRC).
Then check your soldering very carefully on the pins between the 68000 <-> xilinx and xilinx <-> RAM chips. It is possible for a minimig to partly function if there is a fault on these pins. Visually inspect, preferably under a microscope then use a Digital volt meter to look for shorts between adjacent pins and open circuit pins. If none of this shows up where the fault is then I would try an oscilloscope to inspect all these pins for activity, you would be looking for signals with clean high and low levels and not three levels (often a sign that a pin is shorted to the one next door).
I have just built 3 minimigs and my first one suffered from an almost invisible solder bridge between two of the higher address lines which stopped the boot code from successfully copying the kickstart image in to the RAM
Hope that helps, Regards Mark Leman
