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  1. #1

    Weird issue with ABL Z probe : S

    Hello all,

    I recently installed Auto Bed Levelling on my Makerfarm i3v and I noticed the Z probe starts shaking when the Z axis is moving. Today it started shaking a whole lot and then the print just stopped, the LCD done like a refresh and that was it. I tried printing again and about 10 minutes in it happened again. I then unplugged the servo and the print made it all the way through (7 hours).

    Anyone have any idea how I could fix this problem?

    Cheers.

  2. #2
    Super Moderator Roxy's Avatar
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    Its hard to diagnose without actually being there... But it almost sounds like the electronics is taking too much power on one of the supply rails. Can you power the servo from a separate power supply to help debug this?

  3. #3
    Quote Originally Posted by Roxy View Post
    Its hard to diagnose without actually being there... But it almost sounds like the electronics is taking too much power on one of the supply rails. Can you power the servo from a separate power supply to help debug this?
    Unfortunately, no

  4. #4
    Quote Originally Posted by Roxy View Post
    Its hard to diagnose without actually being there... But it almost sounds like the electronics is taking too much power on one of the supply rails. Can you power the servo from a separate power supply to help debug this?
    Should I try plugging it into a different port on the RAMPS board?

  5. #5
    Super Moderator Roxy's Avatar
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    If it is a power problem, that won't help. Remember, the servo gets power from some supply, but it is controlled by the electronics. Not much power is being used to control it. A lot of people have had flakey issues because of power problems with the servos. Myself included! If you can solder 4 D-Cell batteries together, you could power the servo from that. It shouldn't be that hard to find a 5 or 6 VDC wall wart transformer to power it. But really.... If you are fighting a power issue, you need to know that and get that resolved first.

  6. #6
    Quote Originally Posted by Roxy View Post
    If it is a power problem, that won't help. Remember, the servo gets power from some supply, but it is controlled by the electronics. Not much power is being used to control it. A lot of people have had flakey issues because of power problems with the servos. Myself included! If you can solder 4 D-Cell batteries together, you could power the servo from that. It shouldn't be that hard to find a 5 or 6 VDC wall wart transformer to power it. But really.... If you are fighting a power issue, you need to know that and get that resolved first.
    Is there a Gcode command to cut power from the servo?

  7. #7
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    Quote Originally Posted by TehStranger View Post
    Is there a Gcode command to cut power from the servo?
    Check to make sure you don't have this line commented out in your configraton.h in the Bed Auto Leveling section.
    #define PROBE_SERVO_DEACTIVATION_DELAY 300

    This will cut power to the servo 300ms after either an extend or retract of the servo. It seems it's normal for the servo to get a bit jittery from some circuit feedback in the Arduino if it's left powered on and if you're marginal on 5v power at the Arduino it can cause a too low power condition and print stop or a reboot of the Arduino. This will fix that. You can set the ms delay to whatever you want, but most seem to set that to 300ms and it works well.

    I also have had problems with the servo drawing more power than the Arduino 5v can supply and occasionally the Arduino reset during a servo move. So now I leave the Arduino USB connected either to my laptop or my Raspberry Pi and that gives enough extra 5v power that it's no longer an issue.

    Not sure if this helps you, but worth a quick check.

  8. #8
    Quote Originally Posted by Drone View Post
    Check to make sure you don't have this line commented out in your configraton.h in the Bed Auto Leveling section.
    #define PROBE_SERVO_DEACTIVATION_DELAY 300

    This will cut power to the servo 300ms after either an extend or retract of the servo. It seems it's normal for the servo to get a bit jittery from some circuit feedback in the Arduino if it's left powered on and if you're marginal on 5v power at the Arduino it can cause a too low power condition and print stop or a reboot of the Arduino. This will fix that. You can set the ms delay to whatever you want, but most seem to set that to 300ms and it works well.

    I also have had problems with the servo drawing more power than the Arduino 5v can supply and occasionally the Arduino reset during a servo move. So now I leave the Arduino USB connected either to my laptop or my Raspberry Pi and that gives enough extra 5v power that it's no longer an issue.

    Not sure if this helps you, but worth a quick check.
    I'll definitely give it a try, thanks man


    EDIT: It worked like a charm Thank you!!!!
    Last edited by TehStranger; 03-25-2015 at 06:29 AM.

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