The switching power supply circuit does not have any oscillations
Because of the work relationship, the equipment used to switching power supply more, so have access to maintenance of switching power supply, accumulated a little maintenance experience, this time I say switching power supply does not vibrate a little maintenance experience, I hope to give you a point of reference in the maintenance.
Maintenance of switching power supply does not vibrate, you can take the optocoupler as a demarcation point, first determine whether the optocoupler or the optocoupler after the failure, and then step by step to narrow the scope of investigation, the specific operation is as follows: first of all the optocoupler directly short-circuited, the optocoupler short-circuited is very simple, directly a pile of tin weld can be, so that it is equivalent to reducing the photocoupler's internal resistance, short-circuit the optocoupler, and then we measure the voltage, if the measured mains voltage has not changed, the fault in the optocoupler! After the circuit, on the contrary, before the optocoupler circuit. Here switching power supply with light load, some switching power supply no load does not vibrate.
If the fault in the photocoupler before, mainly check whether the AC power input is a problem, whether the capacitor circuit has an open circuit, there is a management chip to check the chip power supply and the chip pin to ground voltage is correct. Although we give the photocoupler short circuit, but also to the same to exclude the photocoupler itself whether there is a failure.
If the optocoupler, check whether the switching transformer has a turn-to-turn short circuit or open circuit, if the switching transformer has a short circuit, then it is necessary to doubt whether the spike absorption circuit is caused by a short circuit, to prevent a misjudgement, because the switching transformer is bad the chances are very small, the pulse-width modulation transistor short circuit will cause the circuit does not vibrate.
If the repair experience is not enough to determine whether the original online damage, it is a little more trouble, remove the measurement, so more accurate. If the removed original is not a problem, then you can troubleshoot its fault associated with the relevant small devices, and gradually narrow the scope of investigation to determine the problem, beard and eyebrows together, which can easily lead to the face of the failure of a blank, do not know where to start.
As for the said vibration, I also make a brief explanation here: AC in the process of becoming DC, AC mains first rectified and filtered into DC for electronic circuits, this circuit includes high-frequency oscillator circuit, that is, DC into a variable frequency or pulse width of the pulse, this part is very important in switching circuits, the input voltage changes or the load increases and decreases, the oscillator circuit will be adjusted through the frequency or pulse width to keep the output stable. Or pulse width to keep the output stable, this is its role, to think about this role of course, we must vibrate, do not vibrate on the switching power supply failure, which is equivalent to adjust the fire or not regulate.
