I have a standard sm-s2309s servo that comes with the Arduino starter kit. I have used it previously, multiple times without issue. Now I'm trying it to use my servo again but am unable to get the servo working. It simply does not respond. The problem could be either in the Arduino or in the servo itself.

I've tried various examples, like the examples from the Arduino book of the starter kit, or the examples of the Servo library reference documentation.

Servo myservo;
myservo.attach(9 /* or 10 */);

Next, I used a multimeter to measure the voltage of the PWM port I use for the servo. The voltage changed depending whether a command for a 10 degree or 160 degree turn was issued - which means that the PWM ports - I tried multiple - are functioning properly.

Basic set-up for testing:

How can I test the servo itself, and perhaps find the issue?

I've opened it up:

  • Measured the wires to test for broken wires
  • It doesn't smell burned.
  • The little "motor" inside has a resistance of 41KOhm
  • 1
    \$\begingroup\$ Edit to add a good, clear, in-focus, properly cropped photo of your setup and the code (using the {} code formatting button) that you are using to test it. \$\endgroup\$
    – Transistor
    Commented Apr 12, 2020 at 15:19
  • 1
    \$\begingroup\$ 41 kOhm is way too much for a winding resistance. Are you sure it's not 41 ohms? \$\endgroup\$ Commented Apr 12, 2020 at 17:05
  • \$\begingroup\$ No, I set the multimeter to 200K. \$\endgroup\$
    – Sebazzz
    Commented Apr 12, 2020 at 18:04

1 Answer 1


If you checked the servo coils for continuity, and it checks out, that should mean it's fine, unless it is somehow mechanically blocked from spinning.
You could also have something between the PWM outputs and the servo itself, we can't be sure since we have neither a schematic nor a picture of your setup.
Thirdly, just measuring a DC voltage on your PWM outputs doesn't have to mean they work properly. Observing them on an oscilloscope would tell you a lot more.
Did you actually open the servo and looked at the small controller board inside?

enter image description here

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Images produced by Byron J at Spakfun (https://www.sparkfun.com/users/468760)

  • \$\begingroup\$ > Did you actually open the servo and looked at the small controller board inside? Did you read my question? I did. \$\endgroup\$
    – Sebazzz
    Commented Apr 12, 2020 at 18:05

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