Discussion on Maintenance Experience of Switching Power Supply
1. If the switching power supply does not start, generally check whether the switching frequency is correct, whether the protection circuit is blocked, whether the voltage feedback circuit and current feedback circuit are normal, and whether the switch tube is broken down;
2. Transformers generate heat or emit a "sizzling" sound, usually due to incorrect switching frequency;
3. The flashing output voltage power indicator light usually indicates a short circuit on the secondary side.
Generally, switch tubes, charging resistors, and rectifier diodes are prone to damage... Therefore, a digital multimeter is usually used for measurement first, and those that are not damaged are tested on power. It would be better to check if there were burnt areas on the surface.
Internal and External Interference of Switching Power Supplies
The interference of switching power supplies is generally divided into two categories: firstly, the interference formed by internal components of switching power supplies; The second is the interference caused by external factors in the switching power supply. Both involve both human and natural factors.
Internal interference of switching power supply:
The EMI generated by switching power supplies is mainly caused by the high order harmonic current interference generated by the basic rectifier and the peak voltage interference generated by the power conversion circuit.
Basic rectifier: The rectification process of a basic rectifier is a common cause of EMI *. This is because the power frequency AC sine wave is no longer a single frequency current after rectification, but becomes a DC component and a series of harmonic components with different frequencies. Harmonics (especially higher-order harmonics) will generate conduction interference and radiation interference along the transmission line, causing distortion of the front-end current. On the one hand, it will cause distortion of the current waveform connected to its front-end power line, and on the other hand, it will generate radio frequency interference through the power line.
