What causes switching power supplies to burn out?
Switching power supply is always burning switching tubes for the following 13 reasons.
1. Soft start circuit failure
2. Switching tube integrated circuit board counter-peak absorption circuit failure
3. Positive feedback is too strong
4. Timing capacitor failure leakage
5. Voltage regulator circuit decoupling capacitor failure
6. Voltage regulator circuit negative feedback open loop
7. Switching tube emission limit current resistance is too small
8. Damage to the switching voltage device
9. Rectifier bridge damage
10. Poor insulation between the switching tube and the heat sink
11. Poor performance or power of the switching tube is too small
12.B + rectifier diode damage
But where the switching power supply is powered on the fuse burned out, we must find out the fault components and in accordance with the original parameters of the optional replacement components, and then replace the same specifications of the insurance! Tube.
13. Input AC voltage is too high or too low
Rectifier diode or flat bridge, filter capacitors, power tubes or power management chips and other failure rate is very high, one of the breakdown damage, there will be a power on the fuse will be burned Failure, must be checked and replaced one by one.
After not burning the insurance, switching power supply no output of the investigation and repair
1, step-down resistor, it is for the circuit to provide the starting voltage, more than the value of the change, open-circuit or false welding, replacement and replacement welding.
2, check and replace the optocoupler and switching transformer primary circuit in the transistor, diode resistance capacitance;
3, switching transformer secondary circuit load short circuit, resulting in switching power supply does not work, can be split to check, you can also disconnect the main load power supply, connect the dummy load, test the groups of
But the voltage to find faults; 4, the switching power supply voltage regulator.
4, switching power supply voltage regulator circuit is faulty, check and replace the resistor, capacitor, diode transistor, etc., until the main output voltage can be adjusted and can be adjusted to the design value.
