[Appalachiatools]

I bought a system a while back and was told and assumed that it had been working. The wiring was sloppy so I cleaned it up a bit but now I'm second guessing the correctness of the wiring. I am using slo-syn MD808 drives (3) x, y, & z - M091-FD09 steppers (3). It has a power supply putting out 62 vdc. First off, are these compatible units? I'm starting to wonder if it was all thrown together. The machine itself is very well built but the computer, which I replaced, the power supply, and drives were very sloppy as if it were all thrown together and the previous owner could not get it running. I've installed Mach3 and set up but can't get nothing to jog. The motors will heat up after a few minutes and seem like they are locked up. They spin very freely when not connected to a power source. Please help as I have no idea of what I am doing. I can't seem to find a wiring diagram on the motors and I hate to assume that they came wired correctly. Thanks!
--Rick

[george4657]

If you google "MD808 slo-syn manual" you will come up with several references to a pdf manual you can download for this driver.
George

[Appalachiatools]

Thanks George, I just found it a while ago and have been going over it. I have already found where my polarities were reversed on my A & B windings. I corrected that and am going over the rest as we speak. I currently have OPTO pin 1 connected to 5v on parallel port. It is reading 2.5 volts on my fluke however. everything else seems to check out. when I plug in my power supply. I'm reading 80vdc across each of the motor windings, A & B at the same time. This does not seem right to me...but as I mentioned earlier, I'm pretty green with all this. But I am an electrician but I guess that makes me pretty dangerous with electronics...I still cannot jog or move the motor. Any help anyone can provide will be greatly appreciated.
--Rick

[acondit]

Thanks George, I just found it a while ago and have been going over it. I have already found where my polarities were reversed on my A & B windings. I corrected that and am going over the rest as we speak. I currently have OPTO pin 1 connected to 5v on parallel port. It is reading 2.5 volts on my fluke however. everything else seems to check out. when I plug in my power supply. I'm reading 80vdc across each of the motor windings, A & B at the same time. This does not seem right to me...but as I mentioned earlier, I'm pretty green with all this. But I am an electrician but I guess that makes me pretty dangerous with electronics...I still cannot jog or move the motor. Any help anyone can provide will be greatly appreciated.
--Rick

Finding the polarities reversed on the steppers is not necessarily an indication of carelessness (unlike sloppy wiring). Reversing the polarity of one stepper winding is sometimes used to get the axis to move in the correct direction, although this is not the only way that it can be done.

Alan

[Appalachiatools]

Thanks Alan, I read further through the drive info I have and realized that. My biggest question is...should I have voltage across both windings, A & B at the same time as soon as my power supply is plugged in? I would have thought 1 winding at a time, as the drive calls for motion, depending on direction.
Thanks, Rick

[keebler303]

If they are pwm or chopper drives, which they almost certainly are, then the peak voltage will be 80V but the average voltage will be much less. Maybe like 80V on one and 3V on the other. Do you have access to a scope? If you are getting the proper signals out, the motor should be moving, if the motor is correctly connected and working properly.

Matt

[Appalachiatools]

I'm not questioning the 80v peak, and it does fluctuate, but it is the same across each of the two windings of the motor (A phase & B phase) at the same time. And as soon as the power supply is switched on. As I mentioned in my last post, I would have thought that one winding should be energized at a time as the driver calls for motion and depending on which direction. Is this not how it is supposed to work? Thanks, --Rick

[keebler303]

You are right. What I am saying is that one winding may not turn all the way off. It may be on 5% duty cycle or something which might fool your meter. Also if it is a microstepping drive, then it is not always "one on one off".

Matt

[Appalachiatools]

Thanks for all your help. I've posted a compatibility question in the mach section of this forum. I believe the problem is just a setting in mach, probably ports & pins, and more probably something really stupid staring me in the face. I'm told that the greatest torque is when the motor is still, which would explain the equal voltage on each winding.

I really appreciate all the knowledge & expertise of those on this site. It's hard to place a value on such a resource. THANK YOU!
--Rick