14 tips that are easily overlooked in the use of multimeters
1. Before using the multimeter, "mechanical zero adjustment" should be performed first;
2. Do not touch the metal part of the test lead with your hands during the measurement process, which not only ensures the accuracy of the measurement, but also ensures personal safety;
3. In a complex environment, it is necessary to pay attention to the influence of the external magnetic field on the multimeter;
4. In order to improve the measurement accuracy, try to keep the pointer of the multimeter in the middle position when measuring. The measuring range should be appropriate, and the needle should be more than half off. Select the range. If the size of the measured object cannot be estimated in advance, try to choose a larger range, and then gradually change to a smaller range according to the deflection angle until the pointer deflects to about 2/3 of the full scale;
5. When using a multimeter to test components with positive and negative polarity such as transistors and electrolytic capacitors, pay attention to the polarity relationship. The black negative should be recorded clearly, and the black in the table is connected with "+". The red test lead is the positive pole, and the black test lead is the negative pole, but the electric block connects the black test lead to the positive pole of the internal battery;
6. If the multimeter needs to change gears, disconnect the test leads first, and then measure after changing gears. Do not shift the gear during the measurement, and dial the neutral gear after the measurement. During the measurement, the selection knob cannot be moved arbitrarily, especially when measuring high voltage (such as 220V) or high current (such as 0.5A), so as not to generate arc and burn out the contacts of the transfer switch. After the measurement is completed, the range selection switch should be turned to the "•" position;
7. When measuring resistance, zero adjustment must be performed every time a gear is changed. Replace the battery with a new one if it cannot be adjusted to zero. To measure R, adjust to zero first, and then to shift gears. When measuring resistance, turn the transfer switch to the electric block first, short-circuit the two test leads, turn "Ω" to zero the potentiometer, and make the pointer point to zero ohms before measuring. Every time the electric barrier is replaced, the ohmic zero point should be readjusted;
8. After the multimeter is used, the transfer switch should be placed in the maximum gear of the AC voltage;
9. If it is not used for a long time, the battery inside the multimeter should be taken out to prevent the battery from corroding other components in the meter;
10. Check the block first when measuring, and measure without looking. Every time you pick up the test lead and prepare to measure, be sure to check whether the measurement category and range selection switch is in the correct position. In order to be safe, this habit must be formed;
11. The dial should be level and the readings should be aligned. When using the multimeter, it should be rotated horizontally, and the line of sight should be facing the needle when reading;
12. When measuring R, it is not charged, and when measuring C, discharge first. It is strictly forbidden to measure resistance when the circuit under test has points. When checking large-capacity capacitors on electrical equipment, the capacitors should be short-circuited and discharged before measurement;
13. The test I should be connected in series, and the test U should be connected in parallel. When measuring current, the multimeter should be connected in series to the circuit under test; when measuring voltage, the multimeter should be connected in parallel at both ends of the circuit under test;
14. If the polarity is not reversed, one hand becomes a habit. When measuring current and voltage, special attention should be paid to the polarity of the red and black test leads not being reversed, and the habit of one-handed operation must be developed to ensure safety.
