General audio system is composed of many independent audio units, such as tuner, card holder, equalizer, LD player or VCD player, AV power amplifier, etc. These units need to be plugged into the 220V AC power plug board. Some people turn off all the plugs when they shut down for convenience; When the machine is turned on, the power is turned on as soon as the latch is opened. Although this method is convenient, there are hidden dangers. Because this operation will generate surge current and reverse peak voltage, these two shocks will often damage audio equipment. Most of the damage to some equipment occurs at the moment when the machine is turned on or off, rather than in normal working conditions.

Surge current: a sound equipment is composed of resistance, capacitance, inductance, transformer and other components. They are all cold before startup. When the machine is started, its resistance is small, so the instantaneous current is large, 2.5-3.5 times of the normal working current. This current is called surge current, which can cause damage to the circuit.

[Audio system] Correct operation method of audio system switch

Reverse peak voltage: Inductors, transformers and other units have a characteristic that when a voltage is added to or removed from the circuit, the unit will generate a back electromotive force to prevent the change of the voltage. When a voltage is applied to the inductive element during startup, it will generate a back electromotive force to prevent the establishment of the voltage. However, the energy of the power supply voltage is continuously flowing, so the back electromotive force only acts as a voltage damping function and has little impact on the circuit. However, the situation is different when the machine is turned off. When the machine is turned off, a back EMF is generated in the circuit without any blocking. This voltage is the back peak voltage, which is 9 times the normal voltage. Although its current is small, its voltage is high, causing an impact on the equipment. Therefore, the surge current and reverse peak voltage of each sound unit act on the sound equipment at the same time, causing a big impact, which is easy to damage the equipment. For this reason, each audio unit * turns on and off one by one. The correct power on sequence is in the direction of the sound source signal flow: turn on the card holder, CD player, LD player or VCD player, tuner, equalizer, * turn on the power amplifier.