Summary of tips for using multimeters in home appliance repairs
Things to note when using a multimeter:
1). Identify the functions of each level of the multimeter.
2). Measure three or four resistances and record them.
3). Measure the AC voltage and record it.
4). Measure the DC voltage and record it.
Multimeter: It is mainly used to measure AC and DC voltage, current, DC resistance, and the number of digits of transistor current amplification. There are mainly two types of common multimeters: digital multimeters and mechanical multimeters.
1)Digital multimeter
On the multimeter, you will see a conversion knob as shown in the picture. The knob refers to the sub-quantity gear.
V~: represents the range for measuring AC voltage.
V-: represents the DC voltage measurement range.
MA: Indicates the range for measuring DC voltage.
Ω(R): Indicates the level of measuring resistance.
HFE: Indicates the gear for measuring resistance.
The red pen on the multimeter indicates the positive pole of the external circuit, and the black pen indicates the negative pole of the external circuit.
Advantages: Anti-magnetic. Easy and accurate reading (digital display)...
2) Mechanical multimeter
The appearance of a mechanical multimeter is somewhat different from that of a digital meter, but their shift knobs are similar and the gears are basically the same.
On a mechanical watch, you will see a dial as shown in the figure. There are eight scales on the dial:
What is marked with "Ω" is the scale used when measuring resistance.
What is marked with "~" is the scale used when measuring AC and DC voltage and DC current.
What is marked with "HFE" is the scale used when measuring triodes.
What is marked with "LI" is the scale for measuring the current and voltage of the load.
What is marked with "DB" is the scale for measuring levels.
3) Use of multimeter
①Digital multimeter: Before measuring, turn to the measurement range. It should be noted that the range marked on the range is the maximum value.
② Mechanical multimeter: The method of measuring current and voltage is the same as the mathematical formula, but when measuring the electric cathode, the reading must be multiplied by the value on the gear to get the measured value. For example: the current gear is "X100" and the reading is 200. The measurement problem is 200
4).Notes:
① To adjust the "zero point" (only found in mechanical watches), before using the watch, first check whether the pointer is on the "zero position" on the left end. If not, use a small screwdriver to slowly turn the "zero point" in the center of the case. Adjust the screw so that the pointer points to the zero position.
②The multimeter should be placed horizontally when used (only available on machines)
③Be sure to determine the measurement content before testing, and turn the range conversion knob to the corresponding gear for the measurement shown to avoid burning the meter. If you do not know the size of the physical quantity being measured, start the test from the large range first.
④The test leads must be correctly inserted into the corresponding sockets.
⑤ During the test, do not rotate the gear change knob arbitrarily.
⑥After use, be sure to adjust the meter-free gear change knob to the maximum range of AC voltage.
⑦ When measuring DC voltage and current, pay attention to the positive and negative poles of the voltage, the flow direction of the current, and the correct connection with the test leads.
