Use a digital multimeter to test the quality of the inductor

Use a digital multimeter to test the quality of the inductor:

In the maintenance of household appliances, if there is a problem with an inductor, simple testing methods are often used to judge its quality. As shown in the figure below, the magnetic ring inductor continuity test can be performed with a digital multimeter. From the figure, the resistance value of the magnetic ring inductor is 0.4Ω. First, turn the range switch of the digital multimeter to the electrical barrier "on-off buzzer" symbol and touch the two ends of the inductor with the red and black test leads. If the resistance value is small, the buzzer in the meter will sound, indicating that the inductor Can be used normally.

When it is suspected that the inductor is open or short-circuited on the printed circuit board, a multimeter can be used to test the resistance at both ends of the inductor L when the power is turned off. Generally, the DC internal resistance of high-frequency inductors is between a few tenths of ohms and several ohms; the internal resistance of low-frequency inductors is between several hundred ohms and several thousand ohms; the internal resistance of medium-frequency inductors is between several ohms and tens of ohms. between. When testing, please note that some inductors have few turns or thick wire diameters, and the DC resistance is very small. This is a normal phenomenon (can be measured with a digital multimeter). If the resistance is large or infinite, it indicates that the inductor has opened circuit.

When it is determined that an inductor is indeed broken, it can be replaced with a new inductor of the same model. Since the inductor is not used for a long time, the pins may be oxidized. In this case, you can use a knife to gently scrape off the oxide, as shown in Figure 2-30.