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Common faults and troubleshooting of power adapter

1、 Line fault

Line fault, including power line damage, no power, contact oxidation, poor contact and so on. Key inspection

Check whether the input line and output line are powered on.

If there is a line fault, it can be solved by replacing the power line.

2、 The output voltage is too low

The following are the main causes of low output voltage:

Two point one

In case of load short-circuit fault of switching power supply (especially DC / DC converter short-circuit or poor performance, etc.), firstly disconnect all loads of the switching power supply circuit and check whether the switching power supply circuit is faulty or the load circuit is faulty. If the load circuit is disconnected and the voltage output is normal, it means that the load is too heavy; or if it is still abnormal, it indicates that the switch power supply circuit is faulty.

Two point two

The failure of filter capacitor or rectifier diode at output voltage end can be judged by replacement method.

Two point three

The performance of the switch tube decreases, which leads to the failure of normal conduction of the switch tube, which increases the internal resistance of the power supply and reduces the load capacity.

Two point four

The bad switch transformer not only causes the output voltage to drop, but also causes the switch tube excitation insufficient to damage the switch tube

2.5 the 300V filter capacitor is poor, resulting in poor load carrying capacity of the power supply, and the output voltage will drop as soon as the load is connected. 3、 Output voltage too high

The high output voltage usually comes from voltage stabilizing sampling and voltage stabilizing control circuit. In the closed control loop composed of DC output, sampling resistance, error sampling amplifier such as TL431, optocoupler, power control chip and so on, the output voltage will rise if any part fails.

4、 The safety tube is normal and there is no output voltage

The safety tube is normal and no output voltage indicates that the switching power supply is not working or has entered the protection state.

The first step is to check the starting voltage value of the power control chip's starting pin. If there is no starting voltage or the starting voltage is too low, check whether the external components and starting resistance of the starting pin are leaking.

If the power control chip is normal, the fault can be quickly found by the above monitoring. If there is start-up voltage, measure whether there is high-level and low-level jump at the output end of the control chip at the moment of startup. If there is no jump, it indicates that the control chip is damaged, the peripheral oscillation circuit components are damaged or the protection circuit is faulty. By replacing the control chip and checking the peripheral components, check one by one; if the jump occurs, most of the time it is the switch tube is defective or damaged.

5、 The insurance is burnt out or blown out

Mainly check the rectifier bridge, diodes, switch tubes and large filter capacitor on 300 v. Cause fuse burning, blackening, may also be caused by anti-interference circuit problems. It is particularly noteworthy that the fuse is burned due to the breakdown of the switch tube, which usually burns out the power control chip and the current detection resistance. Thermistors can easily burn out together with the fuse.

The working principle and common problems of power adapter

Power adapter, whose English name is power adapter, is mainly used for small electronic equipment and electronic appliances power supply conversion equipment, generally consists of shell, power transformer and rectifier circuit. According to the connection mode, it can be divided into desktop type and wall type. According to the type of output current, it can be divided into AC output type and DC output type. At present, it is widely used in notebook computers

Mobile phones, home it equipment and other equipment.

The normal power adapter is marked with power, input and output voltage, current and other indicators of a nameplate. It is worth noting

The input voltage range. Generally speaking, the power adapter with input voltage of 110v-240v can be used worldwide and suitable for all countries and regions. Shenzhen Zhenhuan Electronic Co., Ltd. is committed to design, R & D, production, sales and service

As one of the power supply manufacturing enterprises. Professional design and production of security monitoring power supply and other switching power supply, including outdoor three prevention power supply

Source, conventional switching power supply, power adapter, etc. Input voltage of power adapter produced by Shenzhen Zhenhuan Electronic Co., Ltd

For 110v-240v, international general, welcome to purchase.

In reality, most of the power adapter we come into contact with is switching power supply. Switching power supply refers to through modern electronic technology, control on

Turn off the time ratio of on and off, maintain a stable output voltage of a power supply, power adapter switching power supply is general

It is composed of pulse width modulation (PWM) control IC and MOSFET. It has the advantages of high conversion efficiency, small volume and wide voltage range. Deficiency: it is difficult to maintain when the fault occurs, and the power circuit is greatly disturbed.

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