How to use and precautions for pointer multimeter
1. Preparation for using a pointer multimeter
The pointer multimeter should be placed flat in the working position. Before use, check whether the pointer points to the leftmost zero position. Otherwise, use a small screwdriver to turn the center adjustment screw of the dial to make the pointer point to zero. Before measuring, check the position of the test probe. The red probe should be connected to the red "+" socket, and the black probe should be connected to the black "-" socket.
Turn the range conversion switch to the corresponding range. There are two rotary switches on the meter. First, turn the item to select the gear for the measured item, and then turn the range to select the appropriate range.
When measuring resistance, turn the range conversion switch to the desired ohm range, short-circuit the two probes, and the pointer should be biased to the zero position of the scale line. If it is not at the zero position, adjust the zero position knob to make the pointer point to zero.
2. Precautions for using a pointer multimeter
① A good habit to develop when using a multimeter is to check if the gear position is correct before each measurement. Developing such a habit will greatly reduce the probability of burning the watch.
② The range should be selected as much as possible so that the pointer indicates around two-thirds of the full scale, and the reading is relatively accurate. If you do not know the magnitude of the measured voltage and current, you should choose a large range gear, and then adjust the range according to the reading size to make the reading accurate.
③ When measuring resistance, it is necessary to reset to zero after changing the range gear in order to obtain accurate readings. If it cannot be adjusted to zero, it means that the battery voltage in the table is insufficient and the battery should be replaced.
④ When measuring resistance online, it is necessary to cut off the operation and pay attention to whether there are other components forming a parallel circuit with the measured resistance. If necessary, the resistance can be soldered off from one end of the circuit before measurement. For circuits with electrolysis, the capacitors should be discharged before measuring.
⑤ When using a multimeter, it is important to develop the habit of not touching the metal part of the probe with your hands to prevent electric shock accidents. Meanwhile, touching the metal part of the probe with your hand during resistance measurement can affect the reading.
⑥ When measuring DC voltage, connect the red pen to the "+" and the black pen to the "-" to prevent polarity reversal from causing the pointer to deflect in the opposite direction and damaging it. In the case of not knowing the positive or negative polarity, you can first shift to a large range gear, quickly touch the measured point with a probe, and observe the direction of pointer swing to determine the correct polarity. It is particularly important not to misuse the mA or resistance mode to measure voltage, otherwise it may burn out the instrument.
⑦ When measuring current, never connect the two probes across the power supply to avoid burning out the meter head. A general multimeter can only measure DC current and cannot measure AC current.
⑧ After using the meter, the range switch should be placed in the highest voltage position. For multimeters with short-circuit or disconnect positions, they should be placed in the corresponding position to prevent others from accidentally damaging the meter when using it.
