Which multimeter is good for repairing home appliances and testing electrical appliances?
Basic usage of pointer multimeter:
(1) Before testing, first place the multimeter in a horizontal state and check whether its needle is at the zero point (referring to the zero point of the current and voltage scales). If not, adjust the "mechanical zero adjustment" under the meter head so that the pointer points zero point.
(2) According to the item to be measured, correctly select the measurement item and range switch on the multimeter. If the magnitude of the measurement is known, select the corresponding magnitude range. If the magnitude of the measured value is not known, the measurement should be started by selecting the maximum range. When the deflection angle of the pointer is too small to allow accurate reading, the range should be reduced. Generally, the pointer deflection angle is not less than 30% of the maximum scale as a reasonable range.
(3) The multimeter is used as an ammeter
① When connecting the multimeter in series to the circuit under test, pay attention to the direction of the current. That is, connect the red test lead to the end where the current flows in, and the black test lead to the end where the current flows out. If you don’t know the direction of the current being measured, you can first connect a test lead to one end of the circuit, and gently touch the other test lead to the other end of the circuit. If the pointer swings to the right, it means the wiring is correct; if the pointer moves to the left, Swinging (below zero) indicates that the wiring is incorrect and the positions of the two test leads of the multimeter should be exchanged.
②When the pointer deflection angle is greater than or equal to 30% of the maximum scale, try to use the large range gear. Because the larger the range, the smaller the shunt resistance, the smaller the equivalent internal resistance of the ammeter, and the smaller the error introduced by the circuit under test.
③When measuring large current (such as 500mA), never turn the range selection switch during the measurement process to avoid arcing and burning out the contacts of the transfer switch.
