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How can I tell if a servo's busted? — Parallax Forums

How can I tell if a servo's busted?

skatjskatj Posts: 88
edited 2008-03-02 03:25 in BASIC Stamp
For some reason one of my continuous rotation servos isn't moving at all. I inspected the wires and there's a small portion of the signal wire that looks like the wire tubing has been melted with a soldering iron.

I have been subjecting the servos to quickly-changing pulses (using a radio control system to move them), but my two other servos are fine.

I am powering the servo controller with a 4.8V 250 mAH battery through the breadboard, protected by two 6V rated 10mF capacitors.

It stopped working today. It is relatively new (purchased a few weeks ago). I am certain that the code is correct, because I wrote a very simple program just to see if it'd move at all.


What causes a servo to stop working? My project is on an urgent timeline and I need to know whether its wise to start ordering a new one right away. Is the "melted" wire a sure sign it's broken?

Comments

  • Electroman987Electroman987 Posts: 4
    edited 2008-03-02 01:41
    Ok. heres a start.
    1. Since you've had it, has it been ran before.
    2. If yes. When you ran it, did you do a torque test (ran the servo while holding the servo arm in one place). Common thing to do when you get a servo the first time.
    3. If yes again. Did you hear snapping.
    4. if yes to all question, your servo gears are worn.

    If no at 2, then your wires are touching at the burnt·area or you have a bad servo chip (in the bottom of the servo), so you may have to get a new one. Sorry for the limited help. I need to see to say what it is. I have had years of hobby work though.
  • skatjskatj Posts: 88
    edited 2008-03-02 01:47
    It's ran before, but I never did a torque test.
  • Electroman987Electroman987 Posts: 4
    edited 2008-03-02 01:53
    So it has ran before?

    HMMMMMMMMMMMMMMMM.

    Did it have an "unhappy" meating w/ a soldering iron and for how long?
    Because it may have joined the vcc w/ the data wire or vice versa w/ the gnd wire, therefore disabling any chance for a signal to get to the servo. Not to mention possibly damaging the BS with the shorting of the power sources w/ the I/O pin.
  • skatjskatj Posts: 88
    edited 2008-03-02 01:59
    It's ran for a couple weeks up until today.

    I'm not exactly sure if it was the soldering iron that did the melting. I don't recall specifically any incident of touching the wires accidently, but it's possible I didn't notice. A nearby wire connecting the servo controller to the BS2 is also slightly melted, so perhaps it was a soldering iron.

    If it is the case, is the servo now defunct?
  • Electroman987Electroman987 Posts: 4
    edited 2008-03-02 02:04
    Ok now im confused. are you using a servo contoller or directly from the BS's pins because i heard the servo contoller and the BS aren't compatible. mybe im wrong, but that is what i have heard.
  • skatjskatj Posts: 88
    edited 2008-03-02 02:16
    I am using the parallax servo controller.
  • Electroman987Electroman987 Posts: 4
    edited 2008-03-02 02:25
    Im sorry to say but im affaid i cannot help in this situation. i read too fast and thought it was a servo problem but im not sure anymore because i have not used the servo controller and though it was incompatible w/ the BS in the first place. sorry again for the inconvenience. I can't even tell you where to look because the explanation on it is very vague. Take care and good luck.

    P.S. try using the servo controller program they suggest to test the board and the servo at the same time. They have good documentation on that though.
  • UghaUgha Posts: 543
    edited 2008-03-02 02:27
    Is it possible there was a small break in the insulation of the wires and they crossed somehow and shorted out, melting
    the plastic on their own?
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2008-03-02 02:32
    skatj -

    Have you checked the battery, presuming this is battery powered?

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "Genius is one percent inspiration and ninety-nine percent perspiration."

    Thomas Alva Edison
  • skatjskatj Posts: 88
    edited 2008-03-02 03:25
    I haven't checked the battery, but I am assuming it's in working order since on the Parallax Servo Controller, the other two servos work fine, and when I hook it up to a radio control receiver, which is powered by a different battery, it doesn't work either.
    Ugha said...
    Is it possible there was a small break in the insulation of the wires and they crossed somehow and shorted out, melting
    the plastic on their own?

    The melted wire does not look severe, and the "melted part" is only visible on the white part. Maybe I should snip that part off and splice a working connector.

    Post Edited (skatj) : 3/2/2008 3:35:54 AM GMT
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