A sound system is composed of many independent sound units, such as a tuner, speakers, equalizer, LD or VCD player, and AV amplifier. These units need to be plugged into the 220V AC power plug board. Some people, for the sake of convenience and convenience, turn off the power supply by unplugging the plug when shutting down; When the power is turned on, everything is powered on as soon as the plug is opened. Although this method is convenient, it has hidden dangers. Because this operation will generate surge current and anti peak voltage, which often damage audio equipment. Most equipment damage occurs at the moment of startup or shutdown, rather than during normal operation.
Surge current: A sound equipment is composed of components such as resistors, capacitors, inductors, transformers, etc. They are all in a cold state before starting up. When turned on, its resistance value is small, so the instantaneous current is very large, which is 2.5-3.5 times the normal working current. This current is called surge current, which can cause damage to the circuit.
Off peak voltage: Inductive components, transformers, and other units have a characteristic that when a voltage is applied or removed in a circuit, their units generate a back electromotive force to prevent the voltage from changing. So when a voltage is applied to the inductive component during startup, it generates a back electromotive force to prevent the establishment of this voltage. However, the energy of the power supply voltage is continuous, so this back electromotive force only serves as a voltage damping effect and has little impact on the circuit. However, the situation is different when shutting down. When shutting down, a back electromotive force is generated in the circuit without any obstruction, and this voltage is the anti peak voltage, which is 9 times the normal voltage. Although its current is small, the voltage is high, causing an impact on the equipment. So the surge current and anti peak voltage of each audio unit acting simultaneously on the audio equipment cause a large impact, which can easily damage the equipment. It is recommended that each audio unit be turned on and off sequentially, one by one. The correct boot sequence is to turn on the device in the direction of the audio signal flow: open the card holder, CD player, LD or VCD player, tuner, equalizer, and finally turn on the power amplifier.
The correct shutdown sequence is to turn off the amplifier first, and then turn off other devices. At present, for the sake of convenience, a delayed power plug board has been invented abroad. The first set of sockets is a direct switch socket; The second set of sockets can delay the power connection for 1 second when this machine is turned on; The third set of sockets can delay the power connection for 2 seconds when this machine is turned on; The fourth set of sockets can delay the power connection for 3 seconds when this machine is turned on. Similarly, when shutting down, the power is also turned off at different times. This prevents the phenomenon of surge current and anti peak voltage acting simultaneously on all devices and damaging audio equipment.
