Make necessary preparations before using the multimeter.
A multimeter is a portable instrument with multiple functions and ranges. A typical multimeter can measure DC current, DC voltage, AC voltage, and resistance. Some can also measure inductance and some parameters of semiconductors (such as β). Mastering the usage of a multimeter proficiently is a fundamental skill for electricians. So a multimeter is one of the essential instruments for electricians. Multimeters can be divided into pointer multimeters and digital multimeters.
Due to the variety of types of multimeters, it is necessary to prepare for measurement before use.
① Familiarize yourself with the functions of switches, knobs, sockets, etc., check the dial symbols, "" indicates horizontal placement, and "⊥" indicates vertical use.
② Understand the measured power corresponding to each scale line on the dial.
③ Check if the positions of the red and black probes are correct. Insert the red probe into the "+" socket and the black probe into the "-" socket. Some multimeters also have AC/DC 2500V high voltage measuring terminals. When measuring high voltage, the black probe does not move. Insert the red probe into the high voltage socket.
④ Mechanical zeroing. Rotate the mechanical zero adjustment screw on the multimeter panel to align the pointer with the "0" position on the left end of the dial.
When the probe is short circuited, the pointer cannot be adjusted to zero or the pointer swings back and forth unstably
(1) Replace with a new battery of the same model;
(2) Replace the series resistor;
(3) Adjust the socket spring to ensure good contact, and remove the oxide layer on the probe plug and socket;
(4) Clean the switch contacts of the multimeter with alcohol and calibrate the contact distance between the moving contacts and the stationary contacts;
(5) Use tweezers to press down the moving contact piece in the middle of the zero potentiometer to ensure good contact with the static contact resistance wire;
Resistance range is not connected or the error is too large
(1) Replace the resistor with the same resistance and power;
(2) Wipe and repair poor contact areas with alcohol;
(3) Replace the shunt resistor of this gear;
(4) Replace with a new battery of the same model;
