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:
- Carefully examine the wiring of the servo connection. It should be as follows:
- 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.
- The side pin that goes to the black wire on the servo ribbon cable must be electrically connected to ground (GND).
- The side pin that goes to the white or orange wire on the servo ribbon cable must go to an Arduino digital pin.
- After verifying and correcting the wiring examine the possibility the Servo connector could have been shifted one pin to one side.
- 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.