Electrolytic capacitor detection

A Because the capacity of electrolytic capacitors is much larger than that of general fixed capacitors, the appropriate range should be selected for different capacities when measuring. According to experience, in general, the capacitance between 1 ~ 47μF can be measured by R × 1k block, and the capacitance larger than 47μF can be measured by R × 100 block.

B Connect the multimeter red pen to the negative pole and the black pen to the positive pole. At the moment of contact, the multimeter pointer deflects to the right with a large degree of skewness (for the same electrical block, the larger the capacity, the larger the swing), then gradually turns to the left. Until stopped at a certain location. The resistance at this time is the forward leakage resistance of the electrolytic capacitor, which is slightly larger than the reverse leakage resistance. Practical experience shows that the leakage resistance of electrolytic capacitors should generally be several hundred kΩ or more, otherwise, it will not work properly. In the test, if there is no charging in the forward and reverse directions, that is, the hands are not moving, the capacity disappears or the internal circuit is broken; if the measured resistance is small or zero, the leakage of the capacitor is large or the breakdown is broken. Can no longer be used.

C For electrolytic capacitors whose positive and negative signs are unknown, the above method for measuring the leakage resistance can be used for discrimination. That is, first measure the leakage resistance arbitrarily, remember its size, and then exchange the test leads to measure a resistance value. The one with a large resistance value in the two measurements is the forward connection method, that is, the black meter is connected to the positive pole, and the red meter is connected to the negative pole.

D Using a multimeter electric block, using the method of positive and negative charging of the electrolytic capacitor, the capacity of the electrolytic capacitor can be estimated according to the magnitude of the swing of the pointer to the right.