How to tell if a capacitor is bad?
In the repair and debugging process of electronic equipment, it is crucial to accurately determine whether a capacitor is damaged. A small capacitor that is faulty can cause the entire circuit to not work properly. Today, MobikeChip will share with you several practical methods to help you quickly determine the capacitor is good or bad.
Appearance inspection: visual insight into the failure of the tip
Appearance inspection is the first step to determine whether the capacitor is damaged, but also the most intuitive method. Carefully observe the shell of the capacitor, under normal circumstances, the capacitor shell should be flat and smooth, no obvious deformation, bulging or cracks. If you find the capacitor shell bulging, this is a danger signal, usually means that the internal pressure of the capacitor is too high, may be due to the internal electrolyte dry, short circuit and other reasons, at this time the probability of capacitor has been damaged, continue to use may cause safety problems.
Look at the pins of the capacitor to make sure they are not broken, bent or corroded. The pins are a key part of the connection between the capacitor and the circuit, and if there are problems with the pins, it will lead to poor contact and affect the normal operation of the capacitor. At the same time, pay attention to the logo on the surface of the capacitor, if the logo is ambiguous, it may imply that the capacitor has experienced high temperatures, humidity and other harsh environments, the stability of its performance is in doubt. In addition, if the capacitor is found to have liquid leakage phenomenon, such as traces of electrolyte oozing out of the shell, which also indicates that the capacitor has been damaged, and need to be replaced in a timely manner.
The multimeter measurement: accurate detection of core performance
Multimeter is a common tool to detect the performance of capacitors. First of all, the multimeter will be adjusted to capacitance measurement gear, according to the nominal capacitance value of the capacitor to choose the appropriate range. If you are not sure about the size of the capacitance value, you can start measuring from a larger range first to avoid damage to the multimeter when the range is too small.
Contact the pens of the multimeter with the two pins of the capacitor, and read the capacitance value shown on the display. Under normal circumstances, the measured value should be similar to the nominal value of the capacitor, taking into account the accuracy of the capacitor error, as long as the nominal accuracy within the scope of the capacitance can be considered basically normal. For example, a capacitor with a nominal value of 10μF and an accuracy of ±5%, a measured value between 9.5μF and 10.5μF can be considered normal. If the difference between the measured value and the nominal value is too large, or even infinite or close to zero, it indicates that the capacitor may have an open circuit, a short circuit or a serious leakage problem.
In addition, you can also use the multimeter resistance file to detect the insulation resistance of the capacitor. The multimeter will be adjusted to a high resistance gear, the pen contact capacitor poles, normal capacitors in just contact, the multimeter pointer will have a short swing, and then gradually tend to infinity, which indicates that the capacitor in the charging process of the current changes. If the resistance value is always small, and does not change with time, the capacitor has a leakage phenomenon, has been unable to work properly.
Charge and discharge test: insight into the inner working state
Charge-discharge test on the capacitor, can be more in-depth understanding of its working condition. The capacitor will be connected to a suitable DC power supply circuit, observe the charging process. When a normal capacitor is charging, the current will gradually decrease and the voltage will gradually increase. For example, in a simple RC charging circuit, the charging of a capacitor can be judged by observing the change of the ammeter connected in series in the circuit and the voltmeter connected in parallel at both ends of the capacitor.
After charging is completed, remove the capacitor from the power supply circuit and short the poles of the capacitor with a wire to observe whether there is a discharge phenomenon, such as whether there is a spark (for large-capacity capacitors, the discharge spark may be more obvious). Normal capacitors will discharge quickly when shorted, if there is no obvious discharge phenomenon, indicating that the capacitor may have been damaged, can not normally store and release the charge.
The circuit function analysis: combined with the actual troubleshooting
In the actual circuit, combined with the circuit function to determine whether the capacitor is damaged is also an effective method. If the circuit is abnormal, such as signal distortion, voltage instability, equipment can not start normally, etc., and suspect that the capacitor failure, the capacitor can be removed from the circuit, and then replaced with a known good capacitor of the same specification.
After replacement, if the circuit returns to normal operation, the original capacitor has been damaged; if the circuit is still a problem, it may be other components failures. For example, in an audio amplification circuit, if the sound is garbled or the volume is abnormal, and the sound returns to normal after removing and replacing the coupling capacitor, it is likely that the original coupling capacitor has a leakage or capacity change problem.
At MobikeChip, we not only provide high quality capacitor products, but also committed to provide you with professional electronic component testing knowledge. Knowing how to determine whether a capacitor is damaged or not can make you more skillful in the repair and debugging of electronic equipment. If you have any questions about capacitor testing, selection or other electronic components, please feel free to visit MobikeChip website, our professional team will be happy to serve you.
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