Introduction to common faults of regulated power supply
Fuse blown
Generally, if the fuse is blown, it indicates that there is a problem with the internal circuit of the power supply. Due to the operation of the power supply at high voltage and high current, fluctuations and surges in the grid voltage can cause an instantaneous increase in the current inside the power supply, causing the fuse to blow. Focus on the inspection of rectifier diode, high-voltage filter Electrolytic capacitor, inverter power switch tube, etc. at the power input end, and check whether this component has breakdown, open circuit, damage, etc. If the fuse is indeed blown, you should first check the various components on the circuit board to see if their appearance has been burnt or if there is electrolyte overflow. If the above situation is not found, use a multimeter to measure whether the switch tube has a breakdown short circuit. It should be noted that when a certain component is found to be damaged, it should not be replaced and turned on directly. This is very likely that the replaced component will be damaged due to other high-voltage components still having faults. It is necessary to conduct * * inspection and measurement on all high-voltage components of the above circuit before thoroughly eliminating the fuse blowing fault.
Common faults of regulated power supply
No DC voltage output or unstable voltage output
If the fuse is intact, there is no output of DC voltage at all levels under load. This situation is mainly caused by the following reasons: open circuit and short circuit phenomena in the power supply, faults in overvoltage and overcurrent protection circuits, auxiliary power supply faults, oscillation circuit not working, excessive power load, breakdown of rectifier diodes in high-frequency rectification and filtering circuits, leakage of filtering capacitors, etc. After measuring the secondary components with a multimeter and ruling out high-frequency rectifier diode breakdown and load short circuit, if the output is zero at this time, it can be confirmed that the control circuit of the power supply has malfunctioned. If there is a partial voltage output, it indicates that the front-end circuit is working normally, and the fault is in the high-frequency rectification and filtering circuit. The high-frequency filtering circuit mainly consists of a rectifier diode and a low-voltage filtering capacitor to form a DC voltage output. The breakdown of the rectifier diode will cause the circuit to have no voltage output, and the leakage of the filtering capacitor will cause faults such as unstable output voltage. Using a multimeter to statically measure the corresponding components can detect the damaged components.
Poor power load capacity
Poor load capacity of power supply is a common fault, which usually occurs in old-fashioned or long working power supplies. The main reasons are aging of various components, unstable operation of switch tubes, and failure to timely heat dissipation. Emphasis should be placed on checking for heating and leakage of the voltage regulator diode, damage to the rectifier diode, and damage to the high-voltage filtering capacitor.
