Repair methods of common faults of capacitors

General capacitor failure phenomenon: capacitor open circuit, breakdown, leakage, breakdown after power on.

1. Cause of failure:

1) Open circuit of components

After the capacitor is opened, there is no capacitor function. After an open circuit fault occurs in a capacitor in a different circuit, the specific fault phenomenon of the circuit is different. For example, there is hum after the filter capacitor is opened, and there is no sound after the coupling capacitor is opened, etc.

2) Breakdown of components

After the capacitor breaks down, the function of the capacitor is lost, and the two pins of the capacitor are the path. The DC blocking effect of the capacitor disappears, and the DC circuit of the circuit fails, which affects the AC working state.

3) leakage of components

When the capacitor leaks, the insulation performance between the two plates of the capacitor is reduced, and there is a leakage resistance between the two plates. When a DC current flows through the capacitor, the DC blocking performance of the capacitor becomes worse, and the capacity of the capacitor decreases. When the coupling capacitor leaks, it causes circuit noise. This is a fault with a relatively high incidence in small capacitors, and it is difficult to detect.

4) Breakdown after power on

The capacitor breaks down after the working voltage is applied, and it shows no breakdown after the power is turned off. When the multimeter detects it, it does not show the characteristic of breakdown. When the power is on, the DC voltage across the capacitor is zero or very low, and the capacitor performance is deteriorated .

2. Repair method:

1. Open the internal circuit of the capacitor and replace the components; open the external wiring of the capacitor and re-weld it.

2. Break down the capacitor and replace it with a new one.

3. Leakage of capacitor, replace with new one.

4. Break down after power on and replace with new one.

Maintenance of electrolytic capacitors: electrolytic capacitors are one of the fixed capacitors. Its fault characteristics have many similarities with fixed capacitor fault characteristics. Due to the particularity of electrolytic capacitors, the fault characteristics of electrolytic capacitors have many differences. In the circuit, the failure rate of electrolytic capacitors is high.

1. Failure phenomenon: short circuit of two poles of the capacitor

2. Cause of failure:

1) Without electricity, breakdown, short circuit inside the capacitor.

2) It is normal if it is not energized. After energization, it breaks down and the external connection of the capacitor is short-circuited.

3. Repair method:

1) Replace with new components.

2) The external wiring of the capacitor is short-circuited, check the short-circuit point, and disconnect.