what would make a distributor coil keep going out after new ones are put on.

What is your question?

i have a mazda mpv van 1991 and we had to replace the altornator after it was replaced it would die on me from time to time until it wouldn't start so we had a mechanic check it out he said it was the distributor after that was replaced it still didn't work an he couldn't tell us if the little box on the side of it was suppose to read anything or not so we took it to another machanic an he hooked it to a machine said it was the distributor coil but now it keeps blowing the coil it doesn't stay on any longer than 20 minutes before it kills the new coil we've went thru 4 coils trying to figure out the problem the machine says everything is fine but it still won't turn over the mechanic is stumped what could be wrong with it?