Common faults and maintenance of power adapter
Release time：2019-04-16Preview times：313
In daily life, we often contact with the power adapter. In the process of use, we often encounter some problems, such as the common bad contact, unstable voltage or burned fuse. How can we check and remove them? Let's share the common faults and maintenance of the power adapter.
Common faults and maintenance of power adapter
1、 Line fault
Line fault, including power line damage, no power supply, poor contact oxidation, etc. It is important to check whether the input line and output line are energized.
2、 Output voltage too low
The following are the main causes of low output voltage:
1 switch power supply load short circuit fault (especially DC / DC converter short circuit or poor performance, etc.), at this time, first disconnect all loads of switch power circuit, check whether the switch power circuit fault or load circuit fault. 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 means that the switch power circuit is faulty.
2. The failure of filter capacitor or rectifier diode at output voltage end can be judged by replacement method.
3. The performance of the switch tube decreases, which leads to the failure of normal conduction of the switch tube, the increase of internal resistance of the power supply and the decrease of load capacity.
3、 Output voltage too high
The high output voltage generally comes from the stabilized voltage sampling and stabilized voltage control circuit. In the closed control loop composed of DC output, sampling resistance, error sampling amplifier such as TL431, optocoupler, power control chip and other circuits, any problem of any part will cause the output voltage to rise.
4、 Insurance burned or blown up
Mainly check the rectifier bridge, diodes, switch tubes and large filter capacitors on 300 v. It may also be caused by the problem of anti-interference circuit.
In particular, it should be noted that the fuse burns due to the breakdown of the switch tube, which usually burns the power control chip and the current detection resistance. Thermistors are also easily burned with the fuse.
This is all about the common faults and maintenance of power adapter. In addition, we should pay attention to the daily maintenance of power adapter, which can reduce the occurrence of faults and effectively extend the service life.
5、 Fuse OK, no output voltage
The fuse is normal, no output voltage indicates that the switching power supply is not working or in the protection state. The first step is to check the starting voltage value of the starting pin of the power control chip. If there is no starting voltage or the starting voltage is too low, check whether the external components of the starting pin and the starting resistance are leaking.
Excerpt from Huaqiang power grid
