ABNORMALITY DETECTING CIRCUIT FOR MAGNETIC HEAD

PURPOSE:To execute the highly accurate detection of shorting regardless of the position of a shorting place in a magnetic head by removing a high frequency component with a low pass filter even when an inductance component exists more or less at the time of shorting the head and a head terminal voltage causes ringing. CONSTITUTION:By load resistances R1 and R2 and capacitors C1 and C2 in a differential amplifier AMP, a filter having a time constant in proportion to a product is constituted. Consequently, when resistance values R1 and R2 and capacity values C1 and C2 are determined so that the time constant of the load resistances R1 (R2) and the capacitors C1 (C2) can enter between a period TD of a writing data signal and an average period Tp (TD and Tp are different by one digit or above) of the ringing of head terminal voltage e1 and e2 at the time of shorting, a high frequency component (ringing) is removed from the head terminal voltages e1 and e2. For such a reason, even when the shorting of a head occurs at places Y and Z and an inductance component remains, the abnormality of the head can be detected at the approximately same margin as the shorting at a code X.