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  1. #1
    Join Date
    Oct 2005
    Posts
    225

    48volts and the Picstep Driver

    Will running 48 volts damage the LMD18245's? I think I have ruined my drivers
    due to this. I started running the motors about one week ago and every since the performance has dropped. I kept slowing down the max traverse speed until now they will not run at all hardly. When they do run I can measure about 1.9 amps output but sometimes it only shows .3 amps. I have tested everything and cannot find any thing wrong elsewhere. The motors were spinning smooth and fast and now they are rough missing steps, no torque, will not turn but one directions sometimes just to name a few problems.
    southernexplorer

  2. #2
    Join Date
    Jun 2003
    Posts
    3312
    According the the datasheet, the absolute max is 60V but that would include back emf. The question would be is it possible, sure...did you, maybe. Do you have a oscilloscope? If so, put a load resistor of the value that emulates you coil resistance for each phase of the appropriate wattage. Put it in full step mode and see if you have good square waves swing from ground to your 48V. If you don't then try some different step modes and see if that makes any difference.
    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com

  3. #3
    Join Date
    Oct 2005
    Posts
    225
    I have tried all step modes, I have looked at it on a scope, (the square wave looks good except the leading edge is a little blury) and I have tried different motors and it always acts the same. The motors are very rough. One last questions.
    If a stepper motor rated at 265 oz in is turning say 1 round per second which works out to be 12 IPM on my router should it be fairly easy to stop it?
    southernexplorer

  4. #4
    Join Date
    Jan 2005
    Posts
    1695
    Check your grounding. Use a star ground to the filter cap. (Don't daisy chain the modules)

    Do the motor's vibrate when not in motion?

  5. #5
    Join Date
    Oct 2005
    Posts
    225
    I have two motors running pretty good now. When the other one is running it feels like it is single stepping compared to the others. The others are smooth feeling when running. I may need to program another MCU.

  6. #6
    Join Date
    Jun 2003
    Posts
    3312
    what did you do to get your two motors running smoothly?
    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com

  7. #7
    Join Date
    Oct 2005
    Posts
    225
    I went to the shop one morning and fired it up and two were doing pretty good. But the other one was still rough. It is like it is out of balance or something.
    I ran another motor on the driver today and it runs good so i will have to change them out. I just have to order a pulley for a 5/16" shaft first. The motor that runs good is a 350 oz. in. (compared to 265) nema 23 from slo syn I believe.
    Tommy

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