Well, I have the exact same issue with my 4000T.
The original and a replacement 3640 work just fine, but putting either a MKII or MKIII with a 060 at 50 Mhz will not work. No Kickstartscreen asking for a Workbench disk, not even a trigger of the screen signal. My monitor enters standby mode and when you start the Amiga with the 3640 card in it, it will leave standby and enter the regular display mode asking for the workbench, but with the MK boards, it will not work. Of course the jumpers are in the EXT position, also in a 4000D or 3000T the cards work, so anyone out there who knows why that is???
:-?
