G540 - MOSFET's on Y and A axis' destroyed

**awesomo** · 10-21-2014, 11:08 PM

Hi guys, I need some help. I am new to CNC and I am working on my first build, but I've run into a problem.

I have a rig controlled by a G540 with four 381 oz. Automation Technologies stepper motors connected to it. I had gotten everything connected and was getting movement on all axis'. My problem arose when I went to scale the axis' with Mach3. As the X-axis began it's first movement the machine locked up. Through individual axis testing, I came to realize that the Y and A-axis no longer worked. I found that switching the motors (Y to X and A to Z) yielded movement in those axis', but still nothing in the Y or A.

I sent the board to Gecko and it turns out there was "Customer induced damage". They said the damage is most likely from "shorting motor windings together, reverse polarity, or shorting the motor to GND on both axis". They are repairing the board and sending it back to me.

My question is, how could damage happen simultaneously on two separate axis'? Any thoughts on what the problem could be? I don't want to just plug everything back in, once the board arrives, so what is the best way to track down the problem?

Thank for your help!

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**aarggh** · 10-22-2014, 01:12 AM

Would need to know more about the setup and wiring to really offer any constructive help. Normally the things that destroy drivers are having the steppers disconnected under load. Do you have limits that cut power to part of the rig, that got tripped upon first movement because they were either tripped or had the wrong input value?

The G540's are pretty bulletproof, so unless you changed a switch setting or disconnected a stepper under load, it's very hard to tell what went wrong.

Have you also ruled out any issues with whatever PSU you're using?

cheers, Ian

**awesomo** · 10-22-2014, 11:47 AM

Thanks for the response!

There are limits on the machine, but when movement started and stopped, the gantries were no where near the limit switches.

In terms of the wiring, I extended each stepper wire lead with 20 gauge wire that was soldered together, heat shrinked, then run all the way back to the G540 where I attached the DB9 plugs. There are limit switches on the X and Y axis as well as an emergency stop button, all wired in per Geckos diagram.

For the PSU, I guess I have not tested that. How would the PSU destroy drives on the board? Too much voltage, not enough? I guess one concern could be that I ran 20 gauge wire from the PSU to the G540, could this be an issue? What gauge wire should it be?

Thanks again for your help.