I have a MV1200 too, and had the problem with the Mach chip. Mine didn't exploded, but it blown anyway.
The problem was caused by the PLCC socket, that cracked and was causing bad contact with the Mach chip.
I bought a new chip from AmigaKit. They had it from an old Eyetech inventory. It's working flawlessly so far.
At that time, I remember being in contact with Jens Schoenfeld about this issue, and he told me he could provide me with a new chip if AmigaKit didn't have it.
Try to drop him a message.
Good Luck!
