Поиск и устранение неисправностей метод для переключение питание питание_Устранение неполадок идеи для переключение питание источник питания
Switching power supply is an indispensable part of various electronic equipment, and its performance is directly related to the technical indicators of electronic equipment and whether it can work safely and reliably. Because the key components inside the switching power supply work in the high-frequency switching state, the power consumption is small, the conversion rate is high, and the volume and weight are only 20 percent -30 percent of the linear power supply, so it has become the mainstream product of the regulated power supply. The maintenance of electrical faults of electronic equipment, in line with the principle of starting from easy to difficult, basically starts with the power supply first, and then repairs other parts after confirming that the power supply is normal, and power supply failures account for most of the electrical failures of electronic equipment . Therefore, understanding the basic working principle of the power supply at the beginning, and being familiar with its maintenance skills and common faults will help shorten the maintenance time of electronic equipment failures and improve personal equipment maintenance skills.
1. No output, fuse is normal
This phenomena указывает that the switching power supply is not working or has entered a protection state. First of all, it is required to measure whether the starting pin of the power control chip has a starting voltage. If there is no starting voltage or the starting voltage is too low, check the the starting resistor and the external components connected to the starting pin are leaking. Если мощность контроль чип есть нормальный в это время, the above проверка Неисправности можете быть найдено быстро. Если там есть есть а запуск напряжение, измерение ли вывод терминал из управление чип имеет высокий или низкий уровень скачки в в запуск вверх. Если там есть есть нет прыжок, it означает что the control chip is broken, there is a problem with the peripheral oscillation circuit components or the protection circuit, and the control can be replaced first. Chip, and then check the peripheral components; if there is a jump, it is generally a bad or damaged switch tube.
2. Страхование сжигание или жарка
В основном check the large фильтр конденсатор on the 300V, the diodes of the rectifier bridge, and the switch tubes. Problems with the anti-interference circuit will also cause fuses to burn and blacken. It should be not that the the fuse burnout caused by the breakdown of the switch tube will generally burn out the current detection resistor and the power control chip. NTC thermistors are also easy burned out together with the the fuse.
3. There is output voltage, but the output voltage is too high
This kind of failure generally comes from the voltage regulation sampling and voltage regulation control circuit. The DC output, sampling resistor, error sampling amplifier such as TL431, optocoupler, power control chip and other circuits together form a closed control loop, any problem will cause the output voltage to rise.
4. The output voltage is too low In addition to the voltage regulation control circuit will cause the output voltage to be low, there are also the following reasons that can also cause the output voltage to be low:
b. The Failure of the rectifier diode and filter capacitor at the output voltage end can be judged by the substitution method.
c. The Производительность деградация переключатель трубка воля неизбежно lead to the failure of the switch tube to conduct normally, which will increase the internal resistance of the power supply and reduce the load capacity.
