How to detect LED electronic screen electrolytic capacitors

Electrolytic capacitor LED display is an important component, select the appropriate electrolytic capacitor is very critical, then what is qualified LED electronic screen electrolytic capacitor it? What methods can be detected?

(1) gear selection. Electrolytic capacitor capacity is much larger than the average fixed capacitor, so the measurement should be selected for different capacities of the appropriate range. Under normal circumstances, the capacitor between 1 ~ 100μF Rx100 or Rx1k block can be measured more than 100 wide capacitors available Rx100 or Rx1 block measurement.

(2) polarity discrimination. According to the pin discrimination, the long pin is positive, short pin is negative. For positive, - negative electrolytic capacitors can be used to measure the leakage resistance method to be identified. That arbitrary measure leakage resistance, and then exchange the test pen test, the two measurements in the resistance of the black pen that is the positive, then the red pen is the negative. Test should pay attention to, in order to observe the pointer swing to the right situation, should be repeatedly replaced by two test pins to touch the capacitor until the capacitor is not charging phenomenon so far. , In the use of the above method for testing, should be the correct operation, do not touch with the fingers at the same time the measured capacitance of the two lead 4 feet: otherwise, the body resistance will affect the accuracy of the test, likely to cause miscarriage of justice. LED display manufacturers in Shenzhen, especially the use of multi-meter high-blocking (Rx10k) to measure, if the fingers touch the capacitor at the same time the two pins or two metal parts of the pen will make the pointer back to infinity, giving the tester an illusion , Mistakenly believe that the measured capacitor leakage. With digital multimeter and bridge measurement, the capacitor directly into the capacitor socket, the instrument placed in the appropriate gear to read the capacity.

(3) measure the leakage resistance. The LED electronic multimeter red test leads then negative, the black pen then positive, in the moment of contact, multimeter pointer that is more to the right deflection (for the same resistance block, the larger the greater the swing), and then gradually turn left Until stopped at a certain position. The resistance at this moment is the positive leakage resistance of the electrolytic capacitor. The larger this value, the smaller the leakage current and the better the capacitor performance. The red, black pen reversed, multimeter pointer will repeat the swing phenomenon. The measured resistance at this time is the reverse leakage resistance of the electrolytic capacitor, which is less than the forward leakage resistance. That is, the reverse leakage current is larger than the forward leakage current. In actual use, the electrolytic capacitor leakage resistance can not be too large; otherwise, can not work properly. In the test, if the forward and reverse are not charging phenomenon, that is, the needle does not move, then the capacity disappear or internal circuit; measured resistance is small or zero, indicating that the capacitor leakage or puncture damage, can no longer use.

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