In daily life, we all know that excessive capacitance can cause the circuit board to burn out, resulting in unbearable consequences, especially in factories. So how can we identify capacitor faults? Now, let the editor from the circuit board manufacturer take you to understand the characteristics and maintenance of capacitor damage on circuit boards.

Malfunctions caused by capacitor damage are the most common in electronic devices, particularly in electrolytic capacitors.

Capacitor damage manifests as: 1. Decreased capacity; 2. Complete loss of capacity; 3. Leakage; 4. Short circuit.

Capacitors play different roles in circuits, and the faults they cause have their own characteristics. In circuit boards, digital circuits make up the vast majority, with capacitors mostly used for power filtering and fewer capacitors used for signal coupling and oscillation circuits. If the electrolytic capacitor used in the switching power supply is damaged, the switching power supply may not vibrate and there may be no voltage output; Or if the output voltage filtering is not good, the circuit may experience logical confusion due to unstable voltage, manifested as the machine working intermittently or unable to turn on. If the capacitor is connected between the positive and negative poles of the digital circuit power supply, the fault symptoms are the same as above. This is particularly evident on computer motherboards, where many computers experience the phenomenon of sometimes not being able to turn on and sometimes being able to turn on after several years of use. When opening the chassis, you can often see the phenomenon of electrolytic capacitors bulging. If you remove the capacitors and measure the capacity, it is found to be much lower than the actual value.

The lifespan of a capacitor is directly related to the ambient temperature, and the higher the ambient temperature, the shorter the lifespan of the capacitor. This rule applies not only to electrolytic capacitors, but also to other capacitors. So when searching for faulty capacitors, it is important to focus on checking capacitors that are closer to the heat source, such as capacitors near the heat sink and high-power components. The closer they are, the greater the possibility of damage. I once repaired the power supply of an X-ray flaw detector, and the user reported that smoke was coming out of the power supply. After opening the chassis, I found that there was a 1000uF/350V large capacitor with oil like substance flowing out. After removing it, the capacity was only a few tens of uF. It was also found that only this capacitor was closest to the radiator of the rectifier bridge, while others were far away and intact, with normal capacity. In addition, there have been cases of short circuits in ceramic capacitors, and it has been found that the capacitors are relatively close to the heating components. So there should be a focus on maintenance and search.

Some capacitors have severe leakage and can even be hot to touch with fingers, so these capacitors must be replaced.

When troubleshooting, apart from ruling out the possibility of poor contact, most of the faults are usually caused by capacitor damage. So when encountering such faults, you can focus on checking the capacitor. Replacing the capacitor often surprises you (of course, you should also pay attention to the quality of the capacitor and choose a better brand, such as Ruby, Black Diamond, etc.)

Article source: PCB manufacturerhttp://www.yonghongpcb.com/