I was having a problem with my boss, it has a machine master control. The y axis was not moving some times. So on the advice from people on cnczone I replaced the transistors with # 2n6547. But now it doesn't move in y at all. The transistors I took out is part # ecg238, is the 2n6547 interchangeable with what I had. Also there is what looks like a diode between the two pins on three of the four transistors. Is there supposed to be one on the other one, and if so which one do I need to order. It is a copper color with one black stripe and the number ecg519? This is a great site and is a great help.
Generally when you have a transistor blown, the axis will wiggle a little but won't go. The diodes are there o protect the transistors from inductive currents generated when the motor coil is de-energized. The doide missing should not make it not run. Are you sure you put the transistors in the right way? Does it not do anything at all? One thing you can try is take the belt cover off the front so you can get to the belt. When it is on, you should not be able to turn the motor. It should be locked. You will have to turn it with some force to overcome the detent torque of the motor. It will feel like cogging when you turn the shaft of the motor. If you can turn the motor freely(only detent torque present) then the problem is probably with the transistors. If the motor seems locked and does not move at all (not even shake) then you probably have a problem somewhere upstream of the transistors.
If you search the board you will find literally dozens of threads regarding transistors popping and dead axes. If you search under my name for "transistor" or "dead axis" you will find several.