Switching power adapter is generally composed of shell, power transformer and distillation circuit. There is a nameplate on the power adapter, which will indicate the withstand power, input and output voltage and current. The nominal voltage on the power adapter refers to the voltage when there is no load outside the power supply and there is no current. It is also the maximum voltage that the power supply can output. Knowing the composition of the switching power adapter, once there is a fault, there will be the direction of maintenance.
First of all, you can check whether it is a line fault, whether the power line is damaged, whether the contact port is oxidized, and whether the input and output lines are powered on. If these phenomena occur, the problem can be solved by replacing the power line. Secondly, the output voltage will be too high or too low. If there is a problem with the regulated sampling or regulated control circuit, the output voltage may be too high. When the load of switching power supply is short circuited, the filter capacitor or rectifier diode at the output voltage end fails, and the internal resistance of power supply increases, the output voltage will be too low. This situation can be solved.
Sometimes the fuse tube is normal but there is no output voltage, so now it is necessary to check the starting voltage value of the starting pin to see whether there is leakage. In another case, the fuse is burned out. At this time, the check points are rectifier bridge, diodes, switches and large filter capacitors, but there are also some problems due to the interference circuit. In particular, the breakdown of the switch tube is not only to burn out the fuse, but also to burn out the control chip, current detection resistance and thermistor of the power supply. It can also be said that the whole power adapter can be invalidated.
The above is the basic knowledge of the switching power supply adapter. The switching power supply adapter needs a stable operation environment. In general, pay attention to voltage protection, avoid no-load, short circuit and other protection to prevent the switching power supply adapter from burning out.
