a magnetic head drum of a helical - scan type for video data recording and reading apparatus comprises upper and lower stationary drums securely mounted on a spindle , an intermediate member rotatably supported on the spindle between the drums , and a motor for rotating the intermediate member . the motor comprises a rotor secured to the intermediate member , a stator secured to the upper drum , and a back yoke connected with the rotor through a back yoke retainer such that the stator is interposed between the rotor and the back yoke . this arrangement of the magnetic head drum contributes to effective damping of an electromagnetic noise of the motor caused due to vibration of the stator and back yoke .