Maintenance of low output voltage in switch mode power supply

The reasons for the low output voltage of a switching power supply may include input voltage issues, switch component failures, output inductance issues, filtering capacitor issues, feedback circuit issues, PWM control issues, and load issues. The maintenance method involves checking whether the input voltage is stable and ensuring that it is within the specified range of the equipment; Use an oscilloscope to check the waveform of switch components, identify any abnormalities, and replace damaged switch components; Use a multimeter to check the resistance and short circuit of the output inductor, and replace the damaged inductor; Use a capacitance meter to check the capacitance value of the output capacitor. If the capacitance value is lower than the specified value, it may be necessary to replace the capacitor; Use an oscilloscope to check the feedback signal. If the signal is unstable or has problems, it may be necessary to check and replace the components in the feedback circuit; Use an oscilloscope to check the PWM control signal. If the signal is abnormal, it may be necessary to replace the PWM control chip or reconfigure the control parameters; Check if the connected load exceeds the rated capacity of the power supply. If so, a higher capacity power supply is required.

In addition, the reasons for the low output voltage of the switching power supply also include insufficient working voltage provided by the 220V AC voltage input and rectifier filter circuit to the switching transistor, overcurrent in the load circuit causing the switching power supply load to increase, resulting in a decrease in output voltage, on/off switching errors, and the protection circuit end entering a conductive state due to faults. The methods and steps for identifying faults include disconnecting all loads in the switching power supply circuit to distinguish whether there is a fault in the switching power supply circuit or the load circuit, using substitution method to determine whether the output voltage terminal rectifier diode and filter capacitor are faulty, etc.

Before carrying out maintenance, please ensure safe operation and strictly follow the maintenance manual or manufacturer's recommendations of the relevant equipment. If you are not familiar with the maintenance of switch power supplies, it is recommended to hire professional technicians for repair.