Common failures and maintenance of power adapters
Release time：2019-04-16Preview times：1403We often come into contact with power adapters on a daily basis. We often encounter some problems during use, such as common problems such as poor contact, unstable voltage, or insurance failure. How should we check and eliminate it? Here are some common failures and maintenance of power adapters.
Common malfunctions and maintenance of power adapters
First, the line failure
Line failure, including power line damage without power, contact point oxidation contact such as poor. Focus on checking whether the input line and the output line are energized.
II. Low output voltage
The following are the main reasons for the output voltage pressure:
1 Switched power supply load short circuit failure(especially DC/DC converter short circuit or poor performance, etc.), at this time, first disconnect all the load of the switch power supply circuit, check whether the switch power supply circuit failure or the load circuit failure. If the load circuit is disconnected and the voltage output is normal, it means that the load is too heavy; Or it is still not normal to indicate that the switch power supply circuit is malfunctioning.
2 The output voltage end filter capacitor or rectifier diode failure, etc., can be judged by substitution method.
3 The performance of the switch tube decreases, resulting in the switch tube being unable to turn on normally, increasing the internal resistance of the power supply and reducing the load capacity.
III. High output voltage
High output voltage generally comes from voltage control sampling and voltage control circuits. In the closed control loop formed by DC output, sampling resistance, error sampling amplifier such as TL 431, optical coupling, power control chip and other circuits, any problem with any part will cause the output voltage to increase.
IV. Insurance burned or blown up
The main inspection of rectifier bridges, various diodes, switch tubes and 300 volts on the large filter capacitance and other parts. It may also be caused by problems with anti-interference circuits.
In particular, it should be noted that due to the safety burn caused by the breakdown of the switch tube, the power control chip and the current detection resistor are usually burned. Thermistors are also easily burned with insurance.
The common faults and repairs of power adapters are discussed here. In addition, we must pay attention to the daily maintenance and maintenance of power adapters. This can reduce the occurrence of failures and can effectively extend the service life.
Safety tube normal, no output voltage
The safety tube is normal, and no output voltage indicates that the switch power supply is not working or is in a protective state. The first step is to check the value of the boot voltage of the boot of the power control chip. If there is no boot voltage or the boot voltage is too low, check whether the components and starting resistors of the boot foot leak.
