Measurement of potentiometers and capacitors by multimeter
1. Measuring potentiometer.
Potentiometer, also known as variable resistor, refers to a resistor whose resistance value can be adjusted freely within a certain range. The nominal resistance and resistance change of the potentiometer can be measured with a multimeter
(1) Select the range.
Turn the range selector switch to the appropriate electrical barrier.
(2) Measure the nominal resistance.
Measure the resistance of terminals 1 and 3 of the potentiometer, which is the nominal resistance of the potentiometer
If the resistance value is infinite, it can be judged that the potentiometer is open.
(3) Measure the resistance change.
While slowly turning the rotary shaft of the potentiometer, measure whether the resistance values at terminals 1 and 2 or terminals 2 and 3 change continuously and uniformly. If it is found that the resistance value changes intermittently or has a jumping phenomenon, it can be preliminarily judged that there is a problem of uneven resistance value change or poor contact of the potentiometer.
(4) Determine the type of potentiometer.
When the potentiometer rotates evenly, if the deflection of the pointer of the multimeter is also uniform, it indicates that it is a linear potentiometer; Slower (or faster), it indicates an anti-logarithmic or logarithmic potentiometer.
2. Measure the capacitor with a multimeter.
A capacitor is a common component consisting of two metal plates sandwiching an insulating material (dielectric). A multimeter can be used for qualitative and semi-quantitative quality inspection of capacitors.
①Select the range.
Turn the range selection switch to the appropriate electrical barrier (R×1k or R×10k).
② Measure ordinary capacitors.
When measuring a capacitor with a large capacity (above 5000pF), the pointer of the multimeter will quickly swing to the right and then gradually return to the left end. When the pointer stops, the resistance value pointed to is the insulation resistance of the capacitor. The larger the insulation resistance, the better, generally it should be close to ∞. When measuring a capacitor with a small capacity (below 5000pF), the pointer of the multimeter basically does not move.
③ Measure the electrolytic capacitor.
Electrolytic capacitors are polarized capacitors. When testing, connect the negative electrode of the electrolytic capacitor with a red test lead, and connect the positive electrode with a black test lead. The larger the capacitance, the greater the swing of the watch needle. After each measurement, the two ends of the capacitor should be short-circuited with a test lead to discharge the capacitor. .
