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Unanswered A4988 to DVR2588

Discussion in 'Troubleshooting' started by Larrydoodoo, Sep 26, 2019.

  1. Larrydoodoo

    Larrydoodoo New Member

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    When replacing the stepper drivers, does anything in the firmware need to be modified? My printer is acting funny... when I run a g20, it probes as if the bed were half the size. When homing, the x carriage stops about 3 inches shy of the end stop. Any help would be appreciated.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Sounds like something else is off.
    You reinstalled the microstepping jumpers (all of them should be in place -- 3 per stepper driver)?

    You base reference is here: https://reprap.org/wiki/A4988_vs_DRV8825_Chinese_Stepper_Driver_Boards

    They are the same from the RAMPS perspective although you may need to tune the current somewhat (but that would not account for a 50% difference in the Y axis as you mention). You only get a 10-15% variance with the current pot.
     
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    and no the firmware (Marlin 1.0.x as it came stock) does NOT need to be modified for this combination.
     
  4. Larrydoodoo

    Larrydoodoo New Member

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    Im using the board that came with the robo
     
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Did you remove/replace the jumpers for the stepper drivers?

    Make sure all three are still in place (under each driver card)
     
  6. Larrydoodoo

    Larrydoodoo New Member

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    Sorry it took so long to reply. An update on my issue... since my last reply to this thread, I've replaced the motherboard with a ramps 1.6 board. Mainly because of the upgraded power and heat bed connections, also larger mosfet. I loaded the "Robor1plusV2" firmware on it, still have the same issue, yes, jumpers are installed.

    Sent from my SM-G965U using Tapatalk
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Assuming the hardware is identical, no. You went with the RAMPS 1.6, I can't say if that requires a firmware tweak or not (I suspect NOT, but I do not KNOW).

    Are you sure the firmware is correct otherwise for the R1? That sounds like the axis size numbers might be incorrect. If not then an endstop might be not working correctly.

    ...and that certainly sounds like a faulty endstop.
     
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If the RAMPS itself is not the issue then the stepper drivers are likely your next best bet for a failure.
     
  9. Larrydoodoo

    Larrydoodoo New Member

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    The problem where X stops shy of its end stop is resolved. The drv8825 drivers are new

    Sent from my SM-G965U using Tapatalk
     
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The normal drivers are the A4988, the DRV8825 SHOULD be interchangeable.

    https://reprap.org/wiki/A4988_vs_DRV8825_Chinese_Stepper_Driver_Boards

    However if the current is too low for a channel then the stepper will drop steps. You may need to calibrate that channel (or swap another driver in and see if it is better calibrated). Also they differ here: Max. microsteps A4988 = 16 DRV8825 = 32
    So you may want to make sure the jumpers are set to have them at 16 (not 32) or the steps/axis in the firmware will potentially be incorrect. Stock marlin is configured for the A4988. I do not know if the board you are using totally relies on jumpers or if it supports digital microstep settings: http://marlinfw.org/docs/gcode/M350.html if so you can experiment without touching the hardware, but if it has jumpers it is likely totally configured via them.
     
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