The common faults of electrolytic capacitors are: reduced capacity, disappeared capacity, breakdown short call and leakage, etc., where the change in capacity is caused by the electrolytic solution inside the electrolytic capacitor gradually drying up during use or heating (generally speaking, the high temperature decreases the capacity ), and breakdown and leakage are generally caused by the applied voltage is too high or the capacitor itself is of poor quality.
Precautions
　　1. Because the electrolytic capacitor has positive and negative polarities, it cannot be reversed when used in the circuit: in the power circuit,when a positive voltage is output, the positive electrode of the electrolytic capacitor is connected to the power output terminal, and the negative electrode is grounded. When outputting a negative voltage, the negative electrode is connected to the output terminal, and the positive electrode is grounded.
　　When the polarity of the filter capacitor in the power circuit is reversed, the filter effect of the capacitor is greatly reduced, on the one hand, it causes the power supply output voltage to fluctuate, on the other hand, it is equivalent to a resistor, which is easy to heat. When the reverse voltage exceeds a certain value, the reverse leakage resistance of the capacitor will become very small, so soon after the power is turned on, it may cause the capacitor to burst and damage due to overheating.
　　2. The voltage applied to both ends of the electrolytic capacitor cannot exceed its allowable working voltage, and a certain margin should be left according to the specific conditions when designing the actual circuit. In the design of the filter capacitor of the stabilized power supply, if the AC power supply voltage is 220V, the rectified voltage on the secondary side of the transformer can reach 22V, and the electrolytic capacitor with a withstand voltage of 25V can generally meet the requirements. However, if the AC power supply voltage fluctuates greatly and may rise to more than 250V, it is best to choose an electrolytic capacitor with a voltage of more than 30V.
　　3. The electrolytic capacitor should not be close to high-power heating elements in the circuit to prevent the electrolyte from drying up due to heat.
　　4. For the filtering of signals with positive and negative polarities, two electrolytic capacitors with the same polarity in series can be used as a non-polarized capacitor.