| 摘要 |
PURPOSE:To prevent malfunction due to a pop noise at the time when the power supply is put to work, by providing a memory unit stored with cut-off operation on the basis of the abnormality detection signal of an amplifier and a method of inhibiting the memory unit from operating for a certain time by a delay method. CONSTITUTION:Once the abnormal DC potential of amplifier 11 or abnormality of power loss, heat load impendance, etc., is detected by DC detector 14 or PC detector 15, FF16 is set by the detection signal. By the set signal of FF16, relay driver circuit 19 is stopped and contact 12 is closed, thereby protecting speaker SP. Supplying a reset signal from reset circuit 17 to FF16 allows circuit 19 to operate after delay by delay circuit 20 for a certain time, and contact 12 is made, so that the circuit will become stationary. With the power switch opened, the same operation is performed. While delay circuit 20 is operating at the time of power feeding, inhibit circuit 18 inhibits the setting of FF16 of the memory unit, so that the malfunction of FF16 will be prevented which is caused by a pop noise. |
