Detection methods and techniques of resistors

A) the actual resistance value can be detected by connecting the two markers (regardless of the positive and negative) with the two ends of the resistance. In order to improve the measurement accuracy, the range of measurement should be chosen according to the size of the measured resistance nominal value. Due to the nonlinear relationship between ohm in scale, it in the middle of a degree is relatively fine, so should be as far as possible to scale the middle position, indicating value of the pointer is 20% ~ 80% of full scale starting arc range, in order to make more accurate measurement. According to different resistance error level. The readings are allowed to have an error of plus or minus 5%, plus or minus 10% or plus or minus 20% respectively. If the error range is not consistent, the value of the resistance value is indicated.

B, note: test, especially in measuring more than dozens of k Ω resistance resistance, hand don"t touch the pens and and resistance of the conductive part; The tested resistance is soldered from the circuit, and at least one head must be welded to prevent the other elements in the circuit from affecting the test, causing the measurement error. The resistance of the color ring resistance can be determined by the color ring logo, but it is better to test the actual resistance value with the multimeter in use.

2. Detection of fuse resistor:

In the circuit, when fusing resistors fuse open, according to the experience to judge: if discover black or burning fuse resistor surface, can be concluded that the load is overweight, through many times more than its current rating; If there is no trace on its surface, it indicates that the current flowing through is equal to or slightly greater than its rated fuse value. For the determination of a fuse resistor with no trace on the surface, it can be measured by using the multimeter R * 1 block to ensure the accuracy of the measurement, and the end of the fuse resistor shall be welded down from the circuit. If the measured resistance value is infinite, it is indicated that the circuit breaker has failed to open, and if the measured resistance value is far from the nominal value, the resistance variable value is not suitable for reuse. In the maintenance practice, it is found that a few circuit breakers are short-circuited in the circuit, which should also be noticed in the detection.

3. Detection of potentiometer:

Check the potentiometer, the first to turn the handle, see if turning the handle rotation smooth, switch is flexible, switch on and off when the "click" sound is ringing, and listen to the sound of the potentiometer internal resistance and friction contact point, if there is a "rustling" sound, explain quality is bad. When using the multimeter test, the appropriate resistance of the multimeter is selected according to the resistors of the measured potentiometer, and then the test can be conducted according to the following methods.

A, using the ohm of the multimeter to measure "1" and "2" at both ends, the reading should be the nominal resistance value of the potentiometer. If the needle of the multimeter is not moved or the difference is much, it indicates that the potentiometer has been damaged.