SITUATION: A servo motor emits a burned, chemical smell and maybe some smoke.

 

CAUSE: This is almost always caused by a mistake connecting the power and signal. Two ways this happens are:

  • A wiring mistake
  • Shifting the connector one pin to the right or left when plugging in the servo.

 

CORRECTION: Immediately disconnect the servo from everything. Just pull the plug. Then:

  1. Carefully examine the wiring of the servo connection. It should be as follows:
    1. Center pin goes to a positive voltage, usually 6 volts from a voltage regulator. This is the pin that goes to the center wire on the servo ribbon cable.
    2. The side pin that goes to the black wire on the servo ribbon cable must be electrically connected to ground (GND).
    3. The side pin that goes to the white or orange wire on the servo ribbon cable must go to an Arduino digital pin.
  2. After verifying and correcting the wiring examine the possibility the Servo connector could have been shifted one pin to one side.
  3. Plug the servo back into its circuit taking care the white wire goes to an Arduino digital pin, the red wire goes to +6volts (usually from a voltage regulator), and the black wire to ground.

 

NOTE: A servo that emits a smell or smoke is probably damaged beyond use, even if it turns when presented a signal. It should be discarded.