Multimeter fault diagnosis
Multimeters are used in a wide range of applications, and are the most common in the power electronics sector. They are indispensable for metal rotor flowmeters on both sides. A multimeter can be used not only to measure the resistance of the object being measured, but also AC and DC voltages. Some can even measure the main parameters of transistors and the capacitance of capacitors, etc.
Since the range of use is so wide, the user of the instrument should be able to easily determine its failure. Today we will popularize multimeter fault diagnosis together!
1) Use the observation method to check the components, such as whether there is discoloration, bubbling or spots, etc., whether there is a special smell, etc.
2) If there are two metal rotameters of the same model or new spare parts, the replacement method can be used to diagnose the fault. Therefore, we generally recommend that companies with relatively high frequency of use have a backup instrument.
3) The multimeter's performance is good and bad, which is mostly caused by contact damage or weak soldering. Knocking and hand pressure methods can be used to diagnose faults. For parts that may cause failure, tap lightly to see if it will cause errors or shutdowns. At the same time, you can check the plug and power supply to ensure stable power supply.
4) Sometimes when a metal rotor flowmeter fails when operating in a high-temperature environment, methods such as cooling can be used to eliminate the failure.
Tips for using multimeter
Use a multimeter to determine the quality of piezoelectric ceramics
Piezoelectric ceramic is a synthetic piezoelectric material. When subjected to external pressure, charges will be generated on both sides, and the amount of charge is proportional to the pressure. This phenomenon is called the piezoelectric effect. Piezoelectric ceramics have a piezoelectric effect, that is, they will deform under the action of an external electric field, so piezoelectric ceramic sheets can be used as sound-generating components.
Using the piezoelectric effect of the piezoelectric ceramic piece, a multimeter can be used to judge its quality.
Lead two wires from the two poles of the piezoelectric ceramic piece, then place the ceramic piece flat on the table, connect the two leads to the two test leads of the multimeter, set the multimeter to the minimum current block, and then lightly press the ceramic piece with the pencil eraser. , if the multimeter pointer swings obviously, it means the ceramic piece is intact, otherwise, it means it is damaged.
2 Use a multimeter to determine the positive and negative poles of the speaker
First, set the pointer multimeter to the DC 0~5mA range, and then connect the two test leads to the two solder tabs of the speaker to be tested. Press the paper cone of the speaker gently with your hand and observe the swing direction of the multimeter pointer. If the pointer deflects in the positive direction, the red test lead is connected to the negative electrode of the speaker and the black test lead is connected to the positive electrode of the speaker. On the contrary, the red test lead is connected to the positive pole, and the black test lead is connected to the negative pole.
