With the rapid development of the times, the popularity of domestic industry is very fast at present, and the switching power supply has gradually stepped into the center of the world stage. The volume of the power supply is also slowly becoming templated and miniaturized, and its anti-interference ability is also becoming stronger and stronger. However, things will inevitably fail after a long time, so how to solve these problems? Now let's introduce the repair methods of switching power supply
with the rapid development of the times, at present, the popularity of domestic industry is very fast, and the switching power supply has gradually stepped into the center of the world stage. The volume of the power supply is also slowly becoming templated and miniaturized, and its anti-interference ability is also becoming stronger and stronger. However, things will inevitably fail after a long time, so how to solve these problems? Now let's introduce the repair methods of switching power supply
what are the repair methods of switching power supply?
first, the fuse is blown.
for this fault, first of all, carefully check each original on the circuit board to see whether it is burnt, whether there is electrolyte overflow, and at the same time, smell it to see if there is any peculiar smell. Of course, you can also check it with a multimeter to measure the resistance value of the power input. If it is less than 200K, it indicates that there is a local short circuit at the back end
second, there is no DC voltage output or the voltage output is unstable
first test with relevant equipment to see whether each component of the high-frequency transformer is broken, and then look at the DC voltage at each output end. If the output value is zero at this time, it indicates that the control circuit of the power supply has failed. Finally, use a multimeter to statically measure whether the rectifier diode and low-voltage filter capacitor in the high-frequency filter circuit are damaged
III. poor load capacity of the power supply
this is a common fault, which usually occurs in the old or long-term power supply. When repairing, use a multimeter to focus on checking whether the high-voltage filter capacitor of the zener diode and the current limiting resistance are deteriorated, and then carefully check whether all the solder joints on the circuit board are open welding, virtual connection, etc
IV. there is no DC voltage output, but the fuse is in good condition
this situation indicates that the power supply is not in operation, or has entered the protection state. When repairing, first judge whether the main control chip is in the working state or damaged. If it is damaged, directly replace it. If it is not damaged, focus on checking whether the current limiting resistance of the grid (g pole) of the switching power tube is open welding, virtual connection, and value change, Deterioration and whether the switching power tube itself has poor performance
v. there is DC voltage output, but the output voltage is too high
most of these faults are caused by the condition of the stabilized voltage sampling and control circuit. During repair, the overvoltage protection circuit can be disconnected to make the overvoltage protection circuit inoperative, and then measure the main voltage of the power supply at the moment of startup. If the value is more than IV higher than the normal value, it indicates that the output voltage is too high
VI. the cooling fan does not turn
this problem is mainly due to the condition of the triode or the product itself. At this time, you can borrow relevant equipment to measure. First, check whether the triode is damaged. If not, it means that the fan itself is in trouble. You can unplug it from the circuit board, and then connect a 12V DC to see whether it will rotate. If yes, it means that there is a broken wire or poor contact inside the wire; If it still doesn't turn, the fan must be broken
summary: Well, the above is the introduction of the repair methods of switching power supply. I hope to provide you with some help. I believe that in the future repair process of switching power supply, friends will be more handy and become maintenance experts at home