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Servo Tester Issue

Discussion in 'Troubleshooting and Repair' started by JinTaurus, Dec 2, 2018.

  1. JinTaurus

    JinTaurus

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    Dec 2, 2018
    Hello,

    I'm new to the forums and I was looking for some advice. I recently acquired a CCPM servo consistency tester and I tried it out on two MG996R servos but something isn't going right. Instead of being able to switch modes on the servo tester all three LEDs just light up and blink and the servos just run odd. In pulses. I know it's not supposed to behave this way.

    My guess is one of two things: They are digital servos so the tester is having issues with them or it's the way I'm powering the tester. I've included a picture to show my setup. Am I doing this right or do I need to power the servo tester directly and not use any type of power board/bridge?

    As is before connecting a servo:
    20181202_100817.jpg

    Blinking lights when the servo is connected:
    20181202_101845.jpg

    Any input is appreciated.
     
  2. kellys_eye

    kellys_eye

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    Jun 25, 2010
    What is the maximum current deliverable by the power supply board?

    What is the minimum current the servo needs to operate correctly?
     
  3. JinTaurus

    JinTaurus

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    0
    Dec 2, 2018
    The maximum is 5v with the setup shown.

    This servo operates at minimum 4.8v up to 6v.
     
    Last edited: Dec 2, 2018
  4. kellys_eye

    kellys_eye

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    Jun 25, 2010
    CURRENT, not voltage.......
     
  5. Bluejets

    Bluejets

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    698
    Oct 5, 2014
    Chuck the power module, same with the breadboard and connect 4 x 1.5v AA cells into the tester.
    Neither of the 2 dumped items were ever designed to run servos.
     
  6. JinTaurus

    JinTaurus

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    Dec 2, 2018
    Sorry. The breadboard max current is 700mA
    The servo requires 500mA.
     
  7. Bluejets

    Bluejets

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    Oct 5, 2014
    The servo will at times draw nearer to 1 amp.

    The above suggestion was to eliminate the obvious and work your way back.(if you must but be warned it will return to bite you)
     
    JinTaurus likes this.
  8. JinTaurus

    JinTaurus

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    Dec 2, 2018
    I've also try running power from this:
    20181202_171914.jpg

    But got the same result.

    I dont own a 4 AA battery holder but I'll get one. It seems power is the issue. I just dont understand why the breadboard can't run it.
     
  9. Bluejets

    Bluejets

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    Oct 5, 2014
     
  10. JinTaurus

    JinTaurus

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    Dec 2, 2018
    Well the 4AA battery holder solved the issue. Now I'm dissapointed that my servos turn about 120° instead of 180°. Oh well, they are designed more for torque and that's what I need.

    Thanks everyone for your input and help
     
  11. Bluejets

    Bluejets

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    698
    Oct 5, 2014
    You will find 99.9% of servos are designed for 60 degrees each way.

    Reason for the travel is down to 2 facts.
    The signal range is from 1mS to 2mS and the internal feedback pot mostly has some form of mechanical stopper to protect the innards.
    Both can be overcome by careful (sometimes) modding the pot. Signal can be easy to change if you are providing it.
    If it is provided by say an RC unit, then there are travel adjustments but they may be limited.

    Other than that, there are 180 degree servos out there.
    Link................https://www.banggood.com/buy/180-degree-servo.html
     
  12. JinTaurus

    JinTaurus

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    Dec 2, 2018
    Well to be accurate the servos move 140° which serve my purpose well. The plan is to create a pan and tilt with a camera module to track movement.

    I am familiar with the pots that limit movement as well as the signal range. I dont feel that I'll need to alter the pots for my purpose.

    If you have a good recommendation on a camera module I'd love to hear it. I have a few in mind and I'm trying to stay away from webcams. Keep in mind I'm using the beaglebone black wireless to be the brains behind this project.
     
  13. Bluejets

    Bluejets

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    698
    Oct 5, 2014
    Yes, well, it IS a $7.00 servo after all.

    For future reference, one does not alter the pot. Merely check that at the full range of the mechanical stops allows 180 degrees.
    The travel is taken care of by extending the signal mS range slightly.

    Depends on what your application is exactly.
    As an example I built a pan/tilt system here for FPV on the RC glider which monitors the movement of one's goggles. Headtracker unit and also uses a small ( really small) 170 degree camera fed to a 40 channel tx/rx. Good for the kids. It's almost like being in the cockpit (allbeit only around 100 metres range)
    Not my idea, just an example of what is available these days. Total there was around $50.00.

    There are pan tilt systems that use dedicated stepper motors and really flash control systems. Give expected improved results so worth it if you want that sort of thing I guess.

    Couple of photos of the first camera setup on a pod with the 40 channel transmitter on one side and a voltage regulator on the other. Plugs into the main 11.7v flight battery

    Second set is a $4.00 pan/tilt unit from Hobbyking with a couple of 9 gm servos. Used as a test unit for the headtracker.
     

    Attached Files:

    Last edited: Dec 4, 2018
  14. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Any lack of movement of the servo could be catered for in a suitably pinioned lever arrangement to increase the physical movement.
     
  15. Bluejets

    Bluejets

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    698
    Oct 5, 2014
    Think he requires circular travel distance as in "panning" where the servo is an intrigual part of the gimbal.
     
  16. JinTaurus

    JinTaurus

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    0
    Dec 2, 2018
    The range of the servos will work perfectly for my project.
     
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