How to judge whether the multimeter is normal?

There are two types of multimeters: digital and pointer. The following describes how to determine whether they are normal.

For a pointer multimeter, you can shake it gently in your hand. If the pointer is abnormally flexible and keeps swinging, you can determine that the meter is broken. This is because the shunt resistor in the meter head can make the needle produce damping and quickly stop. Otherwise, the resistor is open or the moving coil is broken.

For the DC voltage range, you can find a battery or DC power supply, and set the meter to a range slightly higher than it (for example, use the 5V range to measure a 1.5 or 3V battery) for measurement. For the AC voltage range, you can use the 250 or 500V range to directly measure the 220V mains.

The resistance range needs to be equipped with batteries to measure. When the test lead is short-circuited, the pointer should swing to the full range, and then use the zero potentiometer to adjust the pointer to the full scale 0Ω position. Each time you change a range, you need to make a slight adjustment to the 0 position. The 10K range also needs to be equipped with a 9V or 15V high-voltage battery to work. Most 9V multimeters use 9v and 1.5v batteries in series in the Rx10K range, so both batteries are indispensable when using this range. The 15v range is generally powered by high and low voltages separately without affecting each other.

For a digital meter, the first thing to do is to install the battery and turn on the power switch. The screen should show something. After turning the knob to the resistance range, short-circuit the test leads. All resistance ranges should show 0Ω, and only the 200Ω range may show a few tenths of an ohm resistance, which is normal. When the beep range is turned, a sound should be heard when the test leads are short-circuited. Then turn the knob to the voltage range. The specific test method is the same as that of the pointer meter.