Patent ID: 8335049

Claim:
A disk drive comprising: a first disk surface comprising a first plurality of servo sectors; a first head coupled to a distal end of an actuator arm; a voice coil motor (VCM) and a first microactuator operable to actuate the first head over the first disk surface; and control circuitry comprising a servo loop operable to control the VCM and the first microactuator in response to the first plurality of servo sectors, the control circuitry operable to: disable the servo loop; after disabling the servo loop, excite the first microactuator with a control signal at a test frequency in order to accentuate a crack in the first microactuator; after exciting the first microactuator, enable the servo loop; and after enabling the servo loop, evaluate the first microactuator to detect the crack in the first microactuator.