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Common Fault Of Switching Power Supply
Oct 11, 2018

1. Fuse Fusing In general, fuse fuses indicate a problem with the internal wiring of the power supply. Due to the power supply operating in a high voltage, large current state, the fluctuation of the grid voltage, surges will cause the power supply within a moment to increase the current and fuse. Focus should check the Power input rectifier diode, high-voltage filter electrolytic capacitor, inverter power switch tube, etc., check this component has no breakdown, open, damaged and so on. If it is a fuse, you should first look at the circuit board on the various components, see if the appearance of these components have been burnt paste, there is no electrolyte overflow, if not found above, then use a multimeter to measure whether the switch tube has a breakdown short.

Need to pay special attention to is: must not detect a component damage, after the replacement of the direct boot, so it is likely that other high-voltage components are still faulty and will replace the component damage, it is necessary to complete the above circuit of all high-voltage components of a comprehensive inspection and measurement, to completely eliminate the fuse-fusing failure.

2. No DC voltage output or voltage output instability If the fuse is intact, there is no output at all levels of DC voltage in the case of a load. This situation is mainly caused by: open circuit in the power supply, short-circuit phenomenon, overvoltage, overcurrent protection circuit failure, auxiliary power failure, oscillation circuit does not work, power overload, high-frequency rectifier filter Circuit rectifier diode is penetrated, filter capacitance leakage, etc. In the measurement of secondary components with a multimeter, the elimination of high-frequency rectifier diode Breakdown, load short-circuit, if the output is zero, it can be sure that the power supply control circuit failure. If some voltage output indicates that the pre-stage circuit is working properly, the fault is in the high-frequency rectifier filter circuit. High-frequency filter circuit is mainly composed of rectifier diode and low-voltage filter capacitor DC voltage output, wherein the rectifier diode breakdown will make the circuit no voltage output, filter capacitance leakage will cause output voltage instability and other failures.

The damaged components can be inspected by measuring the corresponding components at a static meter.

3. Poor power supply load capacity Power supply load poor is a common fault, generally in the old-fashioned or long-time power supply, the main reason is the aging of the components, switch tube work is not stable, not in time to heat dissipation and so on. Should focus on check whether the voltage regulator diode heat leakage, rectifier diode damage, high-voltage filter capacitance damage.

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