Detailed explanation of the use of various functions and precautions of multimeter
(1) First of all, pay attention to personal safety. The wire connecting the probe should not expose the metal wire. When measuring voltage and current online, it is important to develop a habit of one handed operation, with one hand holding the probe like a chopstick. For the convenience of measuring DC voltage, the black probe can also be fixed at the ground wire position (such as inserting it into the ground wire spring at the graphite layer of the TV picture tube, or some heat sink holes connected to the ground wire, and clamping it with a crocodile clip on the ground wire).
During the process of measuring voltage, do not let your hands touch the metal parts of the probes, circuit solder joints, or component metal parts to prevent electric shock.
(2) A pointer multimeter should be zeroed before use, that is, the pointer should be placed at the zero mark.
Use a potentiometer to zero in Ohm mode: Short circuit the two probes and adjust the zero potentiometer so that the pointer is on the right zero mark. Note that every time you change the range of the resistor gear, you need to perform a zero adjustment.
Voltage and current zeroing: Adjust the spring of the meter head, which is the central "one" screwdriver adjustment point, so that the pointer is at the left zero mark.
(3) During the process of measuring voltage or current, if the two probes are still connected, the gear and range cannot be switched, especially under high voltage and high current conditions. Otherwise, the multimeter may be damaged, and in some cases, circuit components may also be damaged.
(4) Do not use the resistance range to measure when the circuit board is powered on (or when there is still electricity in large capacitors, etc.), otherwise it may damage the multimeter.
(5) The current mode of a pointer multimeter cannot measure voltage and resistance when powered on, otherwise high current will damage the meter head. The measurement of current and voltage should not be rotated to the wrong gear. If the resistance or current mode is mistakenly used to measure voltage, it is extremely easy to burn out the multimeter.
(6) If it is found that the digital multimeter has battery symbol display, difficulty in zero adjustment when measuring resistance with a pointer multimeter, and decreased measurement accuracy, it indicates that the built-in battery of the multimeter is low and needs to be replaced. If not used for a long time, the battery should be removed, and for a pointer multimeter, the gear should be set to the off position or the maximum range of AC voltage to prevent damage to the multimeter due to misoperation during the next use.
(7) When measuring in resistance mode, generally do not touch the metal parts of the pins and probes of the components with your hands, especially when the resistance of the components is high. Parallel connection of human body resistance will reduce the resistance value, thereby affecting the measurement accuracy.
(8) Another point is to develop the habit of regularly checking the safety and reliability of one's instruments and tools, as well as whether the measurement function and accuracy are normal. Otherwise, it will cause trouble and misjudgment in the next use, leading to adverse results and putting maintenance and testing in a difficult situation.
