Boss 5 Stepper

[kewl_cat]

I have a Series I Boss 5 z axis stepper that keeps blowing transistors. I switched the stepper from the y-axis and now the z is fine. Two questions: 1) Is there any repairing these motors? It does not seem to have the same magnetism when you turn it by hand. 2) I found a stepper on Ebay for a series II that is a NEMA 43. I could not find the specs on the old stepper.. Would it be possible to use this motor??

[machintek]

S2 NC or S2CNC? Transistors blow because the VAC out of T2 is too high. Anything above 63Vac is getting too high. Also a bad connection can blow a transistor. The current set too high. Wrong transistors?
The magnetic field does decay over time, but also because of heat and vibration. You cannot dis-assemble the motor. The field would collapse. But they can be rebuilt (new bearings, and cleaned) and re-magnetised.

George

[kewl_cat]

It is a S2 CNC.
The voltage is around 58V. If anything out where I am it would be low instead of high voltage. Transistors are 2N6547. I did have to replace the ACC board because the current would not adjust. I also changed the SMD board. I don't remember what the current is off the top of my head but I did set it and it is the same as the others. One interesting note is that when I got the machine all the diodes were removed from the transistor pack on the z-axis. The z-axis would travel a little and then stall and whine. When I put the diodes back in is when it started blowing the #2(from the bottom) transistor. Always the same transistor. I fixed the #2 transistor and diodes and put the Y-axis motor on the z and all is well. Seems like it would be the motor by process of elimination but we have all been humbled a time or two in our life.