Common Faults and Troubleshooting Methods for Power Adapters
Release time:
2022-01-04
1. Line Faults Line faults include issues such as damaged power cords, electrical mismatches, and poor contact due to oxidation at connection points. It is crucial to carefully check whether the input and output lines are receiving power. If a line fault is detected, it can be resolved by replacing the power cord or taking other appropriate corrective measures. 2. Low Output Voltage The following are the primary causes of low output voltage: 1) Short-circuit failure in the switching power supply’s load (especially in DC/DC converters, where short circuits or poor performance may occur). In such cases, first disconnect all loads from the switching power supply and determine whether the issue lies with the power supply circuit itself or with the load circuit. If the output voltage returns to normal after disconnecting the load circuit, the problem is likely due to an overloaded load. If the voltage remains abnormal even after disconnecting the load, the switching power supply circuit itself is defective. 2) Failure of filter capacitors or rectifier diodes at the output voltage terminals. This can be diagnosed by replacing these components. 3) Deterioration of the switching transistor’s performance, causing it to fail to conduct properly, increasing the internal resistance of the power supply and reducing its load capacity. 4) Poor condition of the switching transformer, which not only leads to a drop in output voltage but also results in insufficient excitation of the switching transistor, potentially damaging the transistor itself. 5) Defective 300V filter capacitor, which reduces the power supply’s ability to handle loads—once a load is connected, the output voltage will immediately drop. 3. High Output Voltage High output voltage typically originates from the sampling and voltage regulation control circuits. 4. Blown or Exploded Fuse The main areas to inspect include the rectifier bridge, individual diodes, switching transistors, and the large filter capacitor on the 300V bus. A blown or blackened fuse could also indicate a problem with the anti-interference circuit. Particularly noteworthy: when a fuse blows due to a switching transistor breakdown, the power supply’s control chip and current-sensing resistor often get damaged as well. The thermistor is also prone to being burned out along with the fuse. Liangrui Electronics’ products have passed safety certification standards from developed countries in Europe and the U.S., including UL, CUL, TUV/GS, CE, SAA, and PSE. In response to global energy-saving requirements, all our products comply with ERP, NRCAN, DOE, CEC, and MEPS VI energy efficiency standards. We place great emphasis on environmental protection, and all our products meet RoHS, REACH, California Proposition 65, and other environmental regulations. Our company guarantees that every product leaving our facility undergoes ICT testing, PCBA electrical testing, assembly electrical testing, high-voltage testing, aging tests, and pre-packaging inspections, ensuring that we provide customers with safe, energy-efficient, environmentally friendly, and reliable power supply products. We welcome new and existing customers to call or leave a message for inquiries!
1. Line fault
Line faults include issues such as damaged power cords, electrical mismatches, and poor contact due to oxidation at the connection points. It’s crucial to carefully check whether the input and output lines are receiving power. If the fault is caused by the wiring, it can be resolved by replacing the power cord or taking other appropriate measures.
2. Output voltage too low
The following are the main causes of low output voltage: 1) Short-circuit failure in the switching power supply load (especially short circuits or poor performance in DC/DC converters). In such cases, first disconnect all loads from the switching power supply and determine whether the fault lies in the switching power supply circuit itself or in the load circuit. If the output voltage returns to normal after disconnecting the load circuit, it indicates that the load was excessively heavy; if the voltage remains abnormal even after disconnecting the load, it suggests that there is a fault in the switching power supply circuit.
2) If the output voltage filter capacitor or rectifier diode has failed, you can determine the issue by using the replacement method.
3) The performance of the switching tube has deteriorated, causing it to fail to turn on properly, which in turn increases the internal resistance of the power supply and reduces its load-carrying capacity.
4) A faulty switching transformer not only causes the output voltage to drop but also results in insufficient excitation of the switching tube, thereby damaging the switching tube.
5) The 300V filtering capacitor is defective, resulting in poor power supply load-carrying capability—once a load is connected, the output voltage immediately drops.
3. Output voltage is too high
An excessively high output voltage typically originates from the sampling and voltage regulation control circuit.
4. The fuse blows or burns out.
The primary components to be checked include the rectifier bridge, individual diodes, switching transistors, and the large filter capacitor rated at 300 volts. If the fuse blows and turns black, it could also be due to a problem in the anti-interference circuit. It’s particularly important to note that when a fuse blows because of a switching transistor breakdown, the power supply control chip and the current-sensing resistor are usually damaged as well. Thermistors are also prone to burning out along with the fuse.
Liangrui Electronics Our company’s products have obtained safety certification from leading European and American countries, including UL, CUL, TUV/GS, CE, SAA, and PSE. In response to global new energy-saving requirements, all our products comply with energy-efficiency standards such as ERP, NRCAN, DOE, CEC, and MEPS VI. We place great emphasis on environmental protection, and all our products meet stringent environmental regulations including RoHS, REACH, and California Proposition 65. Our company is committed to ensuring that every product leaving our facility undergoes comprehensive testing—including ICT testing, PCBA electrical testing, assembly electrical testing, high-voltage testing, aging tests, and pre-packaging inspections—providing customers with power products that are safe, energy-efficient, environmentally friendly, and highly reliable.
New and existing customers are welcome to call or leave a message for inquiries!!!
Dongguan Liangrui Group
Tel: +86-18038246588
Tel: +86-13537305053
Fax: +86-769-83795789
Website: www.rico-electronic.net
Email: sales@rico-electronic.net
Address: Room 1101, Building 1, Unit 6, Shidai Zhihui, Luwu Village, Changping Town, Dongguan City, Guangdong Province
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