4. Fixed resistance detection
The actual resistance value can be measured by connecting the two gauges (regardless of positive or negative) with the pins at both ends of the resistance. In order to improve the measurement accuracy, the appropriate range should be selected according to the size of the nominal value of the resistance to be measured.
Note: when testing the resistance of more than tens of thousands of ohms, do not touch the pen and the conductive part of the resistance; The resistance to be measured in the circuit should be welded down from the circuit, at least one foot should be welded, so as to avoid the impact of other components in the circuit on the test, resulting in measurement error; Although the resistance value of the color ring resistance can be determined by the color ring, it is best to test the actual resistance value with a multimeter to judge the resistance.
5. Potentiometer detection
Potentiometer calls variable resistance again, divide line to be wound by material, carbon film, solid type potentiometer.
With the ohm of multimeter block measure potentiometer "head" "tail" two ends, its reading should be the nominal resistance value of potentiometer, if multimeter resistance value differs a lot of, explain this potentiometer fault.
Check whether the movable arm of potentiometer is in good contact with the resistor piece. With the multimeter ohm block measurement "head" and "center end" (or "center end" and "tail") at both ends, the potentiometer rotating shaft according to the counterclockwise direction to close to the head position, then the smaller the resistance value, the better. Then rotate clockwise slowly, the resistance value increases gradually, when the shaft rotates to the "tail", the resistance value should be close to the potentiometer nominal value. If the reading of the multimeter is beating in the process of potentiometer rotation, it shows that the active contact has the fault of bad contact.

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