| 摘要 |
PURPOSE:To decide the clogging of a rotary head according to the presence or absence of a test signal by stopping the drive of a magnetic tape, recording the test signal in an overlap section by a rotary head for record and then reproducing said section by the same head. CONSTITUTION:In a video record pause mode a switch circuit 15 is connected in an adverse state to that of a figure. A control signal Sa is set at ''1'' in the periods Tx and Ty before and after a period Tv in a period T1, and the FM signal Sf is extracted out of a switch circuit 19A only in these periods Tx and Ty. Therefore the signal Sf is recorded in sections 3X and 3Y only of a track 3 as shown by the solid lines of the figure B as long as a head 1A has no clogging. In the next period T2 the track 3 of the figure B is reproduced by the head 1A, and this reproduction signal Sm is supplied to a switch circuit 31A. The signal Sm is obtained from the circuit 31A by control signals Sp and Sa supplied to the circuit 31A and in response to sections 3X and 3Y. Then an LED37 does not glow up. A head 18 performs same procedures in periods T3 and T4 as the head 1A of periods T1 and T2. When the head 1A or 1B has clogging, no signal Sm is recorded in sections 3X and 3Y or no signal Sm is obtained. Thus the LED37 glows up. |
