SELF-DIAGNOSTIC APPARATUS

PURPOSE:To prevent double recording due to defective erasing and erroneous erasing by deciding whether a specified erasing current is applied to a target erasing head to display the warning for disk play. CONSTITUTION:An erase command signal is sent from a system control circuit 1 in order to cause an erasing current to flow into an erasing head 3 corresponding to the track to be erased depending to the recording condition, the erasing current generated in an erasing current generating circuit 2 is supplied to the head 3 with the erase command signal and it is detected whether the specified erasing current is applied to the head 3 from an erasing current detecting circuit 4. It is decided by the detected signal and an erase command signal generated from the circuit 1 whether the specified erasing current is applied to the head 3 corresponding to the track to be erased by the erasing current within an erasing current deciding circuit 8 and thereby a warning is displayed on a display 9. Thereby, double recording due to defective erasing and erroneous erasing can be prevented.