How to use a multimeter to detect some common electronic components

Whenever the board can't run according to normal conditions, there is no problem after checking the line. At this time, it is very likely that the electronic components are broken. If you want to repair, you must find the problem components, and then replace one, but find the faulty components. It is a technical job, but also has certain skills. Today, I will teach you how to use a multimeter to detect some common electronic components .

multimeter

Resistance detection

The most direct method of detecting resistance is to measure with a multimeter resistance file. Generally, the resistance is marked on the resistor. Select the appropriate resistance file and connect the red and black test leads to both ends. If the reading is close, it will be normal, otherwise it will be broken. When making resistance, be careful not to touch the red and black test leads with both hands. It is not dangerous, but to ensure the accuracy of the measured resistance. It is ok to touch one of the test leads by hand.

resistance

Potentiometer detection

Usually, the potentiometer has three pins. First, select the resistance file with a multimeter to test whether the resistance between the two pins of the potentiometer is close to or close to the resistance value marked by the potentiometer. If the difference is much, the potential is indicated. The device is damaged. If the normal multimeter continues to measure the two pins, then the potentiometer is rotated counterclockwise to the position close to the off position. At this time, the resistance value is as small as possible, and then rotated clockwise, and the resistance is gradually increased. Rotate until the last resistance is close to the marked resistance, then the potentiometer is normal.

Potentiometer

Fixed capacitor detection

In addition to using a multimeter to select the appropriate range measurement capacitance value of the capacitor block, you can also use the resistance file to measure. When measuring, you should select the appropriate resistance gear position. Use two meter pens to connect the two pins of the capacitor separately. The resistance value should be infinite. When the resistance value is 0, the capacitor is damaged.

Fixed capacitor

Electrolytic capacitor detection

Electrolytic capacitors and fixed capacitors are measured in a different way. Of course, you can choose to use capacitive blocking to detect. This is the way to use electrical blocking to measure. First select the appropriate resistance file. The red and black pens respectively contact the capacitor. At the two poles, the display value will increase from 0 until the overflow symbol 1 is displayed. If 0 is always displayed, the capacitor is internally short-circuited. If it is always displayed 1, the capacitor is open between the poles. It is also possible to select the resistor file. It should be noted that in the measurement, since the electrolytic capacitor has the positive and negative poles, it must not be reversed here. Usually, the red test lead is connected to the capacitor anode (the length of the foot), and the black test lead is connected to the capacitor cathode (the short one) The pointer multimeter is just the opposite.

Electrolytic capacitor

Inductance detection

Also select the resistance file of the multimeter, connect the test leads to the two ends of the inductor. If the measured resistance value is zero, the internal short circuit of the inductor. Under normal conditions, the DC resistance of the inductor under test and the enamelled wire diameter of the wound inductor coil are used. The number has a direct relationship, as long as the resistance value can be measured, the inductance can be considered normal.

inductance

Diode detection

Turn the multimeter to the detection diode position, connect the anode of the diode with a red test lead, and connect the black lead to the cathode of the diode. If the voltage drop of the diode is displayed on the display (usually the silicon tube 0.5, the tube is 0.2), the diode is normal, and the meter is replaced. If the display shows 1 is normal, otherwise it will be broken. If both test results are 0 or 1, the diode is damaged.

diode

LED detection

Also adjust the digital multimeter to the detection diode block, touch the LED anode with a red pen, and the black pen touches the cathode of the LED (same as the diode above). If it is seen, it indicates normal, otherwise it is damaged.