Bench Testing: Armature
- Test armature for shorted coils using a growler. Hold a flat steel strip on armature parallel to armature core or shaft. Rotate armature in growler. Steel strip will vibrate on area of short circuit.
- Check for grounded coils using a self-powered test light. Place one test lead on armature core or shaft, and other test lead on commutator. Light should not glow. If light glows, armature is grounded and must be replaced.