Introduction to how to use a multimeter for checking circuits
In the case of live electricity, use the AC voltage gear or the DC voltage gear according to the situation! In the case of no electricity, use the resistance gear to detect whether the circuit is in a conducting state or short-circuited!
The multimeter has a buzzer gear. When using the two test leads to measure the same wire, if it is short-circuited, there will be no response. If it is a conducting path, there will be a buzzer sound. Sometimes, if the equipment's casing is live due to poor grounding, you can use the multimeter. Place the red test lead on the casing and the black test lead in direct contact with the ground, and you can measure the electrical leakage intensity of the casing, so that you can know what to expect in the remaining work. Similarly, connect it in series in the circuit to measure the AC and DC current.
To check whether the circuit is leaking electricity, you need to use a megohmmeter (insulation resistance tester), because the voltage of the multimeter is relatively low (9V), while the voltage of the megohmmeter is relatively high (500V). Since the operating voltage of the circuit is 220V, it is difficult to diagnose a circuit with an indistinct leakage. If you want to use a digital multimeter to check the circuit for leakage, first cut off the power supply, discharge the circuit, and then use the resistance gear and the 2M gear for measurement. Normally, the display will be 1 (infinite resistance).
To measure whether the circuit is in a connected state, you can use the ohm gear of the multimeter. When measuring, select the gear where the meter pointer is close to the 0 ohm position. If the circuit is in the electrical circuit, connect one end (end A) of the circuit to the multimeter (red test lead) at the 100 ohm gear, and connect the black test lead to the other end (end B) of the circuit to be measured. If the measurement result is zero, it means that the circuit is connected, also known as a conducting path, and only when there is a conducting path can current pass through the circuit. If, when measuring from end A to end B of the circuit, the pointer of the ohm gear of the multimeter does not approach 0 ohm, it means that the circuit is in an open-circuit state, and an open circuit is also called an open-circuit.
