What should be checked when the DC regulated power supply is damaged?
1. Line failure
Line faults, such as damaged power cords, inability to connect to power, oxidized contact terminals or poor contact. It is important to check that the input and output lines are open. If a line failure occurs, it can be repaired by replacing the power cord.
2. The output voltage is too low
The main reasons for the low output voltage are:
1. The load of the adjustable DC stabilized power supply is short-circuit fault (especially the DC/DC converter is short-circuited or has poor performance). At this time, you can first disconnect and adjust all the loads of the adjustable DC stabilized power supply circuit. Make sure the DC stabilized voltage is correct. Is the circuit open or is the load circuit open? If the load circuit is open and the voltage output is normal, it means the load is too heavy. If it is still abnormal, it means that the adjustable DC circuit is faulty.
2. The fault of the filter capacitor or rectifier diode on the output voltage side can be determined by the exchange method.
3. The performance of the arc-extinguishing chamber decreases, the arc-extinguishing chamber cannot work normally, the internal resistance of the power supply increases, and the load capacity decreases.
4. A bad switching transformer will not only reduce the output voltage, but also cause insufficient excitation of the arc-extinguishing chamber, thereby damaging the arc-extinguishing chamber.
5. The 300V filter capacitor is defective, which will reduce the load capacity and output voltage of the power supply when connecting the load.
3. The output voltage is too high
Excessive output voltage is usually caused by voltage-stabilized induction circuits and voltage-stabilized control circuits. In a closed loop consisting of a DC output, a sense resistor, an error sense amplifier such as a TL431, an optocoupler, a power control chip, and other circuits, one of the components increases the output voltage. The fuse is normal, no output voltage. If the fuse is normal and there is no output voltage, it means that the adjustable DC stabilized power supply is not working or has entered a protection state. The first step is to check the startup voltage value of the startup pin of the power control chip. If there is no start voltage or the start voltage is too low, check the start pin and external components of the start resistor for leakage. If the power control chip is normal, the above monitoring will help you quickly find the fault. If a startup voltage is applied, it will be measured whether there is a high or low level transition at the output of the control chip when it is turned on. If there is no jump, it means that the control chip is damaged, the components of the peripheral oscillator circuit are damaged, or the protection circuit is faulty. By replacing the control chip, check the peripheral components. If replaced, most switch tubes are broken or damaged.
Fourth, the insurance is burned or blown up
Mainly looking for rectifier bridges, diodes, arc chute and large 300 volt filter capacitors. The fuse may be burned or blackened, or it may be due to a problem with the anti-jamming circuit. Special attention should be paid to the fact that the failure of the arc extinguishing chamber will blow the fuse, thereby burning the adjustable DC power control chip and the current detection resistor. Even with insurance, thermistors can burn out easily.
