How to repair the switching power supply?
Abstract：How to carry out the maintenance operation of the switching power supply, what are the commonly used maintenance methods, here sorted out the four methods of the switching power supply maintenance, there are short circuit method, false load method, etc., together to understand.
Four methods of switching power supply maintenance
One is the short-circuit method, the second is the series bulb method, the third is the false load method, and the fourth is the exchange method.
How to carry out the maintenance operation of the switching power supply, what are the commonly used maintenance methods, here sorted out the four methods of the switching power supply maintenance, there are short circuit method, false load method, etc., together to understand.
Four methods of switching power supply maintenance
One is the short-circuit method, the second is the series bulb method, the third is the false load method, and the fourth is the exchange method.
1. Short circuit method
The switching power supply of liquid crystal display device mostly uses the direct sampling voltage regulator control circuit with photoelectric condenser. When the output voltage is high, the short-circuit method can be used to distinguish the defect range.
2, series bulb method
The series bulb method refers to removing the fuse of the input circuit and using a 60W/220V bulb to string the fuse at both ends. After the communication voltage is passed, if the lamp is very bright, it indicates that the circuit has a short circuit. The bulb has a certain level of resistance, such as a 60W/220V bulb, whose resistance is about 800n (refers to thermal resistance), and the bulb plays a certain role in limiting current.
First, it can intuitively identify the defects of the circuit by the brightness of the bulb, and the second is that the current limiting effect of the bulb will not immediately burn out the circuit that has a short circuit.
After cleaning the short circuit defect, the brightness of the lamp will be dimmed, and then remove the lamp and put on the fuse.
3, false load method
In the maintenance of the switching power supply, in order to identify the defect of the load circuit, it is still the power supply itself that presents a defect, it is often necessary to disconnect the load, and test the switching power supply output (usually 12V) with a false load.
The choice of false load is because during the cut-off period of the switching tube, the energy stored in the primary winding of the switching transformer is released to the secondary, if the false load is not connected, the energy stored in the switching transformer is nowhere to release, which is easy to cause the breakdown and damage of the switching tube.
On the selection of false load, the general selection of 30 to 66W/12V light bulb (car or motorcycle) false load, the advantage is intuitive and convenient, according to the light bulb can light and light brightness, can know whether the switching power supply can have voltage output and output voltage up and down.
In order to reduce the initiating current, a 30W soldering iron or a high-power 600Q to 1kn resistor can also be used as a false load.
4. Exchange method
In the liquid crystal display switch power supply, a power control chip is commonly used, and such power control chip is cheap for ten people.
Therefore, when it is estimated that there is a problem with the power control chip, it can be thought of using the exchange method to change.
Four methods of switching power supply maintenance
One is the short-circuit method, the second is the series bulb method, the third is the false load method, and the fourth is the exchange method.
1. Short circuit method
The switching power supply of liquid crystal display device mostly uses the direct sampling voltage regulator control circuit with photoelectric condenser. When the output voltage is high, the short-circuit method can be used to distinguish the defect range.
2, series bulb method
The series bulb method refers to removing the fuse of the input circuit and using a 60W/220V bulb to string the fuse at both ends. After the communication voltage is passed, if the lamp is very bright, it indicates that the circuit has a short circuit. The bulb has a certain level of resistance, such as a 60W/220V bulb, whose resistance is about 800n (refers to thermal resistance), and the bulb plays a certain role in limiting current.
First, it can intuitively identify the defects of the circuit by the brightness of the bulb, and the second is that the current limiting effect of the bulb will not immediately burn out the circuit that has a short circuit.
After cleaning the short circuit defect, the brightness of the lamp will be dimmed, and then remove the lamp and put on the fuse.
3, false load method
In the maintenance of the switching power supply, in order to identify the defect of the load circuit, it is still the power supply itself that presents a defect, it is often necessary to disconnect the load, and test the switching power supply output (usually 12V) with a false load.
The choice of false load is because during the cut-off period of the switching tube, the energy stored in the primary winding of the switching transformer is released to the secondary, if the false load is not connected, the energy stored in the switching transformer is nowhere to release, which is easy to cause the breakdown and damage of the switching tube.
On the selection of false load, the general selection of 30 to 66W/12V light bulb (car or motorcycle) false load, the advantage is intuitive and convenient, according to the light bulb can light and light brightness, can know whether the switching power supply can have voltage output and output voltage up and down.
In order to reduce the initiating current, a 30W soldering iron or a high-power 600Q to 1kn resistor can also be used as a false load.
4. Exchange method
In the liquid crystal display switch power supply, a power control chip is commonly used, and such power control chip is cheap for ten people.
Therefore, when it is estimated that there is a problem with the power control chip, it can be thought of using the exchange method to change.
