Four common causes of power adapter damage

four common causes of power adapter damage

Table of Contents

As personal intelligent mobile devices become more popular, power adapters have become essential necessities in people’s daily lives. However, power adapters often get damaged during use. So what are the reasons for the damage? This article will provide a detailed introduction.

I. Circuit failure

Circuit failures include situations such as power cord damage and poor contact caused by oxidation of the connector. It is necessary to check whether the input line and output line are powered on. If it is a circuit failure, it can be solved by replacing the power cord and other means.

II. Low output voltage

The main reasons for low output voltage are as follows:

1. Short-circuit faults of switching power supply load, especially short-circuit or poor performance of DC/DC converter. At this time, all loads of the switching power supply circuit should be disconnected to check whether it is a fault of the switching power supply circuit or the load circuit. If the voltage output is normal after the load circuit is disconnected, it indicates that the load is too heavy; otherwise, it indicates that there is a fault in the switching power supply circuit.

2. Failures of output voltage terminal filter capacitor or rectifying diode can be judged by replacement method.

3. The performance of the switching tube declines, causing the switching tube to fail to conduct normally. This will increase the internal resistance of the power supply and reduce the load capacity.

4. Defective switching transformer not only causes the output voltage to drop, but also damages the switching tube due to insufficient excitation of the switching tube.

5. Defective 300V filter capacitor causes poor load capacity of the power supply, and once connected to the load, the output voltage will drop.

four common causes of power adapter damage

III. High output voltage

High output voltage generally comes from the stabilizing sampling and stabilizing control circuit. In the closed control loop composed of DC output, sampling resistor, error sampling amplifier such as TL431, optocoupler, power control chip and other circuits, any problem with a component will cause the output voltage to rise.

If the fuse is normal but there is no output voltage, it means the switching power supply is not working or in protection state. The first step is to check the startup voltage value of the startup pin of the power control chip. If there is no startup voltage or the startup voltage is too low, check whether the startup element and startup resistor are leaking.

If the power control chip is normal, the fault can be located by using the above detection method.

If there is a startup voltage, it is necessary to measure whether there is a high or low level jump at the output end of the control chip at power-on moment.

If there is no jump, it indicates that the control chip is damaged, peripheral oscillation circuit components are damaged, or the protection circuit has a fault. It can be checked by replacing the control chip and checking the peripheral components one by one.

If there is a jump, in most cases, it is caused by a faulty or damaged switching tube.

IV. Fuse burned out or exploded

Mainly check the rectifier bridge, various diodes, switching tubes and large filter capacitors on 300 volts. The reason for the fuse burning out or blackening may also be that the anti-interference circuit has problems. It should be noted that when the fuse is burned out due to the breakdown of the switching tube, the power control chip and current detection resistor are usually burned out together. In addition, the thermistor is also easily burned out with the fuse.


In summary, common causes of power adapter damage include circuit failure, low output voltage, high output voltage, and fuse burning out or exploding. By understanding these reasons, people can take measures to prevent damage to their power adapters and prolong their lifespan. Contact JPTPOWER to provide you with the best power adapter products.


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