can mach3 burnout transistors on a CNC control board?

[Robin Hewitt]

sorry robin thats way over my head, if i see some thing that needs replacing i can do it, but understanding what all the bits do is something else, how would i test a diode with a meter, i found the last faulty part with the continuity setting on a test meter, by following and compairing the circuits from each motor controller transistor, simple sience, but thanks,

Think of it as water moving down a pipe. If you turn the sink tap off too quickly the water doesn't want to stop moving so the pressure goes exceedingly high momentarily. It stresses your plumbing and makes a loud clonk.

The diode acts like a magical one way valve that connects the two ends of the pipe work together with no distance in between. Now when you turn the tap off too quickly the water doesn't have to stop. It can go through the magic valve to the pipe start and keep moving round and round the circuit. No clonk.

Do you have diodes? If not, that is why your transistors are exploding.