Pointer multimeter test electrolytic capacitor
1. Because the capacity of electrolytic capacitors is much larger than that of ordinary fixed capacitors, when measuring, you should choose a suitable range for different capacities. According to experience, in general, the capacitance between 1 and 47μF can be measured with R×1k gear, and the capacitance larger than 47μF can be measured with R×100 gear.
2. Connect the red test lead of the multimeter to the negative pole, and the black test lead to the positive pole. At the moment of first contact, the pointer of the multimeter will deflect to the right with a large deflection (for the same electric resistance, the larger the capacity, the larger the swing), and then gradually to the left Turn around until it stops at a certain position. The resistance at this time is the forward leakage resistance of the electrolytic capacitor, which is slightly larger than the reverse leakage resistance. Practical use experience shows that the leakage resistance of electrolytic capacitors should generally be above several hundred kΩ, otherwise, it will not work normally. In the test, if there is no charging phenomenon in the forward and reverse directions, that is, the hands of the watch do not move, it means that the capacity has disappeared or the internal circuit is broken; if the measured resistance value is very small or zero, it means that the capacitor has a large leakage or has been broken down. Can no longer be used.
3. For electrolytic capacitors with unknown positive and negative signs, the above method of measuring leakage resistance can be used to identify them. That is, first randomly measure the leakage resistance, remember its size, and then exchange the test leads to measure a resistance value. The one with the larger resistance value in the two measurements is the positive connection method, that is, the black test lead is connected to the positive pole, and the red test lead is connected to the negative pole.
4. Use a multimeter to block electricity, use the method of forward and reverse charging the electrolytic capacitor, and estimate the capacity of the electrolytic capacitor according to the size of the pointer swinging to the right.
Inductor Detection
Put the multimeter in the resistance gear, and connect the red and black test leads to any terminal of the color code inductor. At this time, the pointer should swing to the right. According to the measured resistance value, it can be identified in the following three situations:
1. The resistance value of the measured color code inductor is zero, and there is a short-circuit fault inside it.
2. The DC resistance value of the measured color code inductor is directly related to the diameter of the enameled wire used to wind the inductor coil and the number of winding turns. As long as the resistance value can be measured, the measured color code inductor can be considered to be normal. of.
