Key Points to Note for Testing Resistors with a Multimeter
What is the detection method for resistors? It may sound simple, but it's not that simple either. In addition to the correct operation, it's also important to pay attention to some small details. In order to make it easier for everyone to operate, the editor has compiled some materials for reference:
1. Roughly estimate the resistance value of a resistor based on its color ring or nominal value.
2. Place the probes of the multimeter on both ends of the resistor and measure R1.
3. If you have high requirements for the test results, you can swap the probes and measure in reverse again, and the result will be R2.
4. If R1=R2 and R1, R2 are close to the nominal value of the resistor, it indicates that the resistor is normal; If R1 and R2 are greater than the nominal values, it can be determined that the resistor is damaged; If the resistance is close to 0 ohms, it indicates that the resistor is open. Under normal circumstances, the test results should be the same. If the two test results are different, the reasons should be identified.
Notes:
1. Preparation before measuring with a multimeter.
Pointer multimeter: Insert the probe into the corresponding probe socket and turn the switch to the corresponding ohm position; Short circuit the two probes and check if the pointer points to the zero position of the ohm gear. If not, adjust it using the ohm gear zero knob.
Digital multimeter: Insert the probe into the corresponding socket and turn the conversion switch to the corresponding ohm range; Turn on the power, short-circuit the probe, and observe if the display screen shows zero; If it is not zero, this number needs to be subtracted from the measurement result, as shown in the figure.
2. Resistors with different resistance values should be measured using different gears. When measuring with a pointer multimeter, generally, resistors below 50Q Ω use R * 1 gear, resistors between 50-1000K Ω use Rx10K gear, resistors between 1-500k Ω use R * 1K gear, and resistors above 500k Ω use R * 10k gear. When a pointer multimeter is zeroed, it needs to be reset again for each gear shift. For a digital multimeter, if the reading is not zero after the probe is short circuited, this number needs to be subtracted at the end of the measurement.
3. When testing, especially when measuring resistors with tens of kiloohms or more, be careful not to touch the conductive parts of the probes and resistors with your hands. Because the human body has a certain resistance, it will have a certain impact on the test results, causing the readings to be smaller.
4. If the tested resistor is installed in the circuit, it can be soldered off from the circuit, at least it should be soldered?! One end to prevent other components in the circuit from affecting the test results and causing measurement errors.
5. If there is oxidation at the lead end of the resistor, the oxide layer should be removed first before measurement.
