Potentiometer detection and resistance detection
Potentiometer detection and resistance detection
Digital method
The numeric method uses three digit numbers to represent the nominal values of components. From left to right, the first two represent valid figures, while third indicates 10 degrees (n = 0~8). When n = 9 is a special case, it represents 10-1. A resistor marked 0 or 000 indicates a jumper and a resistance value of 0g, which is mainly used for labelling of patch elements. For example, 471 = 4709105 = 1Mg2R2 = 2.2.
Resistance detection
(1) The actual resistance value can be measured by connecting two forms (no positive or negative) to the two ends of the resistor respectively. In order to improve the measuring accuracy, the range of measuring resistance should be chosen according to the size of the measured resistance.
(2) the deviation between reading and nominal resistance is 5%, 10% or 20% respectively. If it does not match and exceeds the range of deviation, it indicates that the resistance has changed. In order to touch the conductive part and resistance of the pen, when measuring the resistance on the circuit board, at least one head should be welded to prevent other elements in the circuit from affecting the test and causing measurement errors.
Note: when testing, especially when the measuring resistance is more than tens of KQ,
Detection of potentiometers
(1) ohmic blocks of multimeter must be measured with "1" and "2" ends. The reading should be the nominal resistance of the potentiometer. If there are many differences, potentiometers will be damaged.
(2) check whether the contact between the movable arm of the potentiometer and the resistor is good. Measure the two ends of "1", "2" (or "2", "3") with the ohm of the multimeter. The rotating axis of the potentiometer rotates counterclockwise, approaching the "closed" position, and the smaller the resistance, the better. Then slowly rotate the shaft handle clockwise, and the resistance gradually increases. When the axle handle is tightened to the limit of "3", the resistance value should be close to the nominal value of the potentiometer.