The precautions before using a digital multimeter to measure aircraft electrical and electronic circuits are as follows:
(1) Before measuring the circuit, the measured circuit must be carefully studied. Taking the Boeing aircraft as an example, first look up the SSM and WDM manuals, find out the connection relationship between the tested circuit and other circuits, and formulate a measurement plan to avoid mismeasurement .
(2) When you borrow a digital multimeter from the tool room, because it is a measurement tool, you must check whether it is within the calibration period when you borrow it.
(3) When using the resistance gear of the digital multimeter to measure, the plug of the aircraft battery must be unplugged, and a sign that no power is allowed to be hung on the ground power socket, and the principle of not being able to measure resistance with power
but. Line measurement workers must wear anti-static wrist.
(4) On an airplane, when using a digital multimeter to measure resistance, it is necessary to select the common end as the position of zero potential. Generally, we connect one end of the line to the common ground wire or electrostatic hole of the airplane or
Some rivets. The grounding of the test lead should be reliable, and should not be connected to the insulating layer (such as the painted surface of the aircraft skin, the place where the machine parts are painted) or the place with oil dirt, so as to avoid poor contact. In order to judge whether the grounding of the test leads is good, you can ground the red and black test leads at the same time, and observe the resistance value to check.
(5) When measuring at the socket or plug, you should see the label of the jack or pin to avoid measurement errors. The two test leads cannot touch each other, they cannot be attached to the case, and they cannot touch other pins or sockets. Otherwise, the measurement results will be inaccurate
