By chance have you checked if there is a continuity/resistance from one of the windings to the frame of the stepper?
--J. Ray Mitchell Jr. jrmitche...@gmail.com "Good enough is the enemy of excellence"author unknown On Tue, Dec 8, 2020 at 3:17 PM John Dammeyer <jo...@autoartisans.com> wrote: > Hi Gene, > > > From: Gene Heskett [mailto:ghesk...@shentel.net] > > On Tuesday 08 December 2020 02:04:49 John Dammeyer wrote: > > > > > > I think I'd be measuring the ohmage and inductance of each winding > > > > in that motor. A partially shorted winding would be on my suspects > > > > list. > > > > > > > > They should match within a few %. A 10% diff would condemn it in my > > > > CET mind. > > > > > > > > Cheers, Gene Heskett > > > > -- > > > > > > Thanks for the suggestion. > > > I'll check that too although I'm leaning to epoxy PC board material > > > converted to conductive carbon. > > Unfortunately I can't see which transistor pins go to which terminal > pins. But it appears there isn't a lot of conduction between the winding > pins since without the motor connected nothing gets warm. > > The winding resistances are the same and actually motion is quite smooth. > > But with the 58.5VDC toroidal power supply meant originally to run a 4 > axis stepper conversion there's lots of power there to create the specified > current. Now assume for example it's 7 amps and the motor measures at 1.2 > ohms on each winding. That's 8.4V steady state across the winding or 58W > in the motor. > > Now we know of course the chopper design will apply the 58V for as long as > needed to maintain say the 7A at the top of the micro-stepping curve. So > assume we have 2 ohms DC resistance in a now burnt traces in between > layers. With 7A through that 2 ohms there's a 14V drop. Not a big deal > with the 58V supply. But 14V and 7A is 98W. Easily enough to slowly raise > the temperature. And for all I know the resistance is even higher. > > I hit ESTOP which removes DC power. Plugged the motor back in. ESTOP off > and the reflective temperature probe shows the bottom pin of the connector > quickly reach 40C from 22C. During all this time the motor itself is > barely warm. > > A far east stepper driver rated for up to 110VDC and 8A is on the way. Be > here next Wednesday so then I can verify that it's the driver. > > And no answer back from Gecko. > John > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
