Safety y capacitors in switching power supply damage causes
Capacitors as electronic components used in switching power supplies, play a protective role, that is, after the failure of the capacitor, without endangering personal safety.
y capacitor in addition to meet the corresponding grid voltage withstand voltage, but also requires that this capacitor in the electrical and mechanical properties have enough safety margin, to avoid the extremely poor environmental conditions in the breakdown of short-circuit phenomenon, y capacitor voltage withstand voltage. In addition to the corresponding grid voltage resistance, it is also required that this capacitor has enough safety margin in terms of electrical and mechanical properties, to avoid the phenomenon of short-circuit breakdown in extremely harsh environmental conditions.
Analysis of y capacitors in the switching power supply damage causes can be divided into
1: Capacitor internal short, broken circuit damage, the failure phenomenon is burned switching tube and other current-limiting components, such as insurance and current-limiting resistors in the switching power supply. Capacitor short, broken Road damage working in high voltage, high current (such as colour TV switching power supply, line output circuit) in the filter capacitor, when for some reason the voltage rises, and More than its withstand voltage value, so that the breakdown of short circuit damage, or due to rectifier diode damage so that the polarity of the electrolytic capacitor equivalent to work in the AC circuit, in the The larger reverse leakage current under the heat and short-circuit damage. Due to the short-circuit current flowing through the capacitor is very large, the general capacitor will burst or make its sealing rubber plug bloat out. Filter capacitors short-circuit, often fuse or current-limiting resistor burned out, power supply thick film block or switching tube, rectifier tube breakdown and other failures. The main performance of the whole Machine "three no", this failure in all types of switching power supply with commonality.
2: capacitor capacity reduction caused by inefficiency or slight leakage, the failure phenomenon is the TV image "S" shape distortion or line out of sync phenomenon, for the current IIC bus Television sets with some special failure phenomenon, if the impact of the synchronised card critical state, the accompanying sound may affect the quality of the television set, making the accompanying chapter at any time. The main reason is that the parameters of the capacitors are changed. The main reason is that the parameters of the capacitor change, but not completely failed, to a certain extent, there is still a role, but not up to the role that should be, making the existing fault phenomenon. Failure phenomenon appears. And this kind of fault is not good judgement and elimination.
3: capacitor capacity disappears caused by failure, complete leakage or burst, is the power supply capacitor failure is the most difficult to judge and repair the fault, because measuring capacitor components, using a multimeter to test everything is normal, but after the capacitor is installed in the circuit, the capacitor capacity is completely disappeared, which is the most difficult to repair the circuit of the soft faults of One, that is, the components can not withstand the voltage, the presence of a voltage, it is easy to completely disappear.
