With the popularity of personal smart mobile devices, it has become one of the most important daily necessities for people. What is the main reason for the damage of the adjustable DC stabilized power supply in daily use? Today we will take a look at the solutions to the problems encountered by most engineers.
1. Line failure
Line failure, such as damaged power cord, power failure, oxidation of contact terminals or poor contact. Focus on checking whether 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. Adjustable DC stabilized power supply load short-circuit failure (especially DC/DC converter short-circuit or poor performance) At this time, you can disconnect and adjust all loads of the adjustable DC stabilized power supply circuit. Ensure that the DC stabilized voltage is correct. Is the circuit disconnected or the load circuit disconnected? If the load circuit is disconnected 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 failure 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 the load is connected.
3. The output voltage is too high
Excessive output voltage is usually caused by voltage-stable induction circuits and voltage-stable control circuits. In a closed loop composed of DC output, detection resistors, error detection amplifiers such as TL431, optocouplers, power control chips and other circuits, one of the components increases the output voltage. The fuse is normal and there is no output voltage. If the fuse is normal and there is no output voltage, it indicates that the adjustable DC stabilized power supply does not work or has entered a protection state. The first step is to check the start voltage value of the start pin of the power control chip. If there is no starting voltage or the starting voltage is too low, please check whether the external components of the starting pin and the starting resistor are leaking. If the power control chip is normal, the above monitoring will help you quickly find the fault. If the start-up voltage is applied, it will measure whether there is a high and low level jump when the output terminal of the control chip is turned on when it is turned on. If there is no jump, it means that the control chip has been damaged, the components of the peripheral oscillator circuit have been damaged, or the protection circuit is faulty. Check the peripheral components by replacing the control chip. If replaced, most of the switch tubes are damaged or damaged.
4. Insurance was burned or blown up
Mainly looking for rectifier bridges, diodes, arc extinguishing chambers and large 300 volt filter capacitors. The insurance may be burned or blackened, or it may be caused by a problem with the anti-interference circuit. Special attention should be paid to the fact that the failure of the arc extinguishing chamber will blow the fuse, which will burn down the adjustable DC power supply control chip and the current detection resistor. Even with insurance, the thermistor is easy to burn out.