Causes of failure of digital multimeters * Ordinary digital square meters generally have resistance measurement, on-off sound detection, and diode forward voltage measurement. AC and DC voltage and current measurement, triode magnification and performance measurement, etc. Some digital multimeters have added functions such as capacitance measurement, frequency measurement, temperature measurement, data memory and voice reporting, which bring great convenience to the actual detection work. However, due to improper use of digital square meters, it is easy to cause damage to the components in the meter during actual detection, resulting in failure. The precautions in use of the digital multimeter are for the reference of beginners, so as to prevent the damage of the digital multimeter as much as possible.
Digital multimeter failure causes and preventive measures:
1. In most cases, the damage of the digital multimeter is caused by the wrong measurement gear. For example, when measuring AC mains, the measurement gear is selected to be placed in the electrical block. In this case, once the pen contacts the mains, the multimeter will be damaged in an instant. Internal components damaged. Therefore, be sure to check whether the measurement gear is correct before using the multimeter to measure. After use, set the measurement selection to AC 750V or DC 1000V, so that no matter what parameter is wrongly measured in the next measurement, it will not cause damage to the digital multimeter.
2. Some digital multimeters are damaged because the measured voltage and current exceed the range. If the mains is measured at the AC 20V gear, it is easy to cause damage to the AC amplifier circuit of the digital multimeter, so that the multimeter loses the AC measurement function. When measuring DC voltage, the measured voltage exceeds the measurement range, which is also likely to cause circuit failure in the meter. When measuring the current, if the actual current value exceeds the range, it will generally only cause the fuse in the multimeter to blow, and no other damage will be caused. Therefore, when measuring voltage parameters, if you do not know the approximate range of the measured voltage, you should first set the measurement gear to ***, and then change the gear to measure the value to obtain a more accurate value. If the voltage value to be measured is far beyond the maximum range that the multimeter can measure, a high-resistance measurement lead should be provided. Such as detection of high anode high voltage and focus high voltage of black and white color TV.
3. The upper limit range of DC voltage of most digital multimeters is 1000V, so when measuring DC voltage, the maximum voltage value is below 1000V, which generally will not damage the multimeter. If it exceeds 1000V, it is very likely to cause damage to the multimeter. However, the upper limit of the measurable voltage may be different for different digital multimeters. If the measured voltage exceeds the range, the method of reducing the resistance of the resistor can be used to measure it. In addition, when measuring the DC high voltage of 40O~1000V, the test leads must be in good contact with the measurement place, and there should be no jitter. Otherwise, in addition to causing damage to the multimeter and making the measurement inaccurate, the multimeter can be used in serious cases. show.
4. When measuring resistance, be careful not to measure with electricity.
