Patent ID: 6014282
Filing Date: 2000-01-11
Classification: G11B

Abstract:
A magnetic disk apparatus comprising:detection means for detecting first to fourth burst signals corresponding to first to fourth burst data items recorded on a recording medium in order to position a head;calculating means for calculating a first value expressed by ((the first burst signal)-(the second burst signal))/((the first burst signal)+(the second burst signal)) and a second value expressed by ((the third burst signal)-(the fourth burst signal))/((the third burst signal)+(the fourth burst signal)) from amplitudes of the first to fourth burst signals detected by said detection means;control means for moving said head to a position at which the first value and the second value obtained by said calculating means coincide with each other;storage means for storing a reference value with which abnormality of said head is determined;first determination means for determining whether or not difference between an absolute value of the first value and the reference value stored in said storage means when said head has been moved to the position at which the first value and the second value coincide with each other by said control means is larger than a predetermined value; andabnormality detection means for detecting abnormality of said head in a case where said first determination means has determined that a difference value between the absolute value of the first value and the reference value is larger than the predetermined value.