Switching power supply overhaul experience
1, switching power supply does not start vibration, generally check whether the switching frequency is correct, whether the protection circuit is blocked, the voltage feedback circuit, the current feedback circuit is not a problem, whether the switching tube breakdown, etc.;.
2, the transformer is hot or issued a "zzzzzzzzzzzzzzz" sound, generally the switching frequency is not correct.
3, the output voltage power supply indicator light flashes a flash is generally a short circuit on the secondary side.
General switching tube, charging resistor, rectifier diode are relatively easy to be bad ...... so generally first with a digital multimeter measurement, no bad in the power detection. If the surface can be seen on the surface of a burnt place is better to check.
Switching power supply internal interference and external interference
Switching power supply interference is generally divided into two categories: one is the switching power supply internal components to form the interference; the second is due to the influence of external factors and make the switching power supply interference. Both involve human factors and natural factors.
Switching power supply internal interference:
Switching power supply EMI is mainly generated by the basic rectifier generated by the high harmonic current interference and power conversion circuit generated by the spike voltage interference.
Basic rectifier: the rectification process of the basic rectifier is a common cause of EMI*. This is because the industrial frequency AC sinusoidal wave through the rectifier is no longer a single frequency current, but into a straight current component and a series of harmonic components with different frequencies, harmonics (especially the high harmonics) will be generated along the transmission line of conduction interference and radiation interference, so that the front-end current distortion, on the one hand, so that the current waveform connected to the power line on the front of the distortion, on the other hand, through the power line to generate radio frequency interference.
