* Question
| What are the detection methods for Resistorss and potentiometers? |
* Answer
| (1) Appearance inspection For the fixed resistance, first check the mark is clear, the protective paint is intact, no scorch, no scratches, no cracks, no corrosion, and the Resistors body is in close contact with the lead.For the potentiometer, the shaft should be checked for flexibility, tightness and comfortable feel.If there is a switch, check if the switch is working properly.For the pointer multimeter, since the electric blocking indication is non-linear, the larger the resistance is, the denser the indication is. Therefore, if the appropriate range is selected, the deflection angle of the hands should be larger, indicating that the 1/3 to 2/3 full scale is indicated.The reading is more accurate.In addition, the multimeter can be used to electrically block the resistance of the Resistors in the detection circuit when it cannot be charged.On-line detection should first be powered down, then disconnect the Resistors from the circuit and measure.
2 Fuse resistance and sensitive resistance detection The fuse resistance is generally only a few to several tens of ohms. If the measured resistance is infinite, it is blown.For a positive temperature system (PTC) thermistor, the resistance is generally small at normal temperature. In the measurement, the hot soldering iron is close to the Resistors. At this time, the resistance should be significantly increased, indicating that the resistance is normal.The component is damaged, and the negative temperature thermistor is the opposite.3 varistor and potentiometer detection First measure the resistance between the two fixed ends is normal, if it is infinite or zero ohm, or the difference between the nominal and the error, beyond the allowable range of error, it means that the damage;The resistance is normal, and then the multimeter’s meter pen is connected to the potentiometer sliding end.If there is a jump or jitter during the rotation, it indicates that the sliding point is in poor contact with the Resistors. (3) Measuring the resistance with a bridge If it is required to accurately measure the resistance of the Resistors, it can be tested by a bridge (digital). |
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