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46483 2008 年 01 月 13 日 01:18 Reading (loading. ..) Comments (0) Category: Original Literature
1 Fixed capacitors for testing the detection
A little less than 10pF capacitance below 10pF
Fixed capacitors for the capacity is too small to be measured with a multimeter, only qualitative checks whether there is leakage, an internal short circuit or breakdown . Measurement, it can use multimeter R? 0k block, with two tables document any connection capacitance, respectively, two pins,
paul smith sale, the resistance should be infinite. If the measured resistance (pointer to the right swing) is zero,
designer handbags, then the capacitance leakage damage or internal breakdown. B detection 10PF ~ 0.01μF capacitors have charged a fixed phenomenon, and then judge the good or bad. Multimeter use R? K block. Β value of two transistors are above 100, and the tunneling current to be small. Choice of models, such as silicon transistor formed 3DG6 composite pipe. Multimeter's red and black table pen and composite pipe, respectively, the emitter and collector c e phase. Amplification of the composite transistor, the measured capacitance of the charge-discharge process to be enlarged, so that meter rate increase put pointer, and thus easy to observe. It should be noted: In the test operation, especially in the smaller capacity of the capacitance measurement, the measured capacitance pin to repeatedly swap contacts A, B two points in order to clearly see the swing meter pointer. C for more than a fixed capacitor 001μF, available multimeter R? 0k block directly test whether the process of charging the capacitor and the availability of an internal short circuit or leakage, according to the size of a pointer to the right swing to estimate the magnitude of the capacitor capacity.
2 electrolytic capacitors because of the detection
A electrolytic capacitor is much greater than the average fixed capacitor, so measurements should be the appropriate choice of different size range. Based on experience, under normal circumstances, 1 ~ 47μF capacitor between, the available R? K block measurement, the capacitance can be larger than 47μF R? 00 block measurements.
B to the red multimeter pen then negative, then positive the black pen in the new to the moment, the meter pointer deflection is greater skewness to the right (for the same power block, the greater the capacity, the greater the swing), then gradually turn to the left until stopped at a location. At this point the resistance is positive electrolytic capacitor leakage resistance,
designer handbags cheap, this value is slightly larger than the reverse leakage resistance. Practical experience shows that the leakage resistance of electrolytic capacitors should generally be more than a few hundred kΩ, otherwise, it will not work properly. In the test,
burberry bags, if positive, no charge reverse phenomenon, namely Biaozhen not move, then lost the capacity or the internal circuit; if the measured resistance is very small or zero,
paul smith wallet, indicating that a large capacitor leakage or breakdown damage can not be used. C for the positive and negative signs of unknown electrolytic capacitors can be measured using the above method to determine leakage resistance. That is, first measured about any leakage resistance, remember its size, and then swap table T and then a resistance test. Two major resistance measurement is that a positive connection, the black test is positive then, the red pen then is negative. D multimeter power block, to the electrolytic capacitor is used,
paul smith bag, the reverse charge method, according to the size of a pointer to the right swings can estimate the electrolytic capacitor.
3 test
A variable capacitor gently rotating shaft, should feel very smooth and should not feel tight and sometimes loose even when the cable wiring. The axial load before and after, up, down, left, right and other directions promotion, the shaft should not be loosening. B rotating shaft with one hand, one hand moving light touch the outer edge of the tablet group and should not feel any loose phenomenon. Shaft and moving piece of poor contact between the variable capacitor, can not continue to use. C placed in the multimeter R? 0k block, a hand table T respectively, then the two variable capacitors and fixed film fixed chip terminal, the other hand will slowly rotating shaft a few back and forth, multimeter pointer location should be fixed in the infinite. In the rotating shaft of the process, if the pointer points to zero sometimes, that action films and short circuit between the stator; If you hit a certain point, the multimeter reading is not infinite but a certain resistance, indicating that dynamic variable capacitor between the plate and stator leakage phenomenon.
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