Digital Multimeter also known as multimeter, multi-purpose table, multi-purpose meter or three meters, is a multi-purpose electronic measuring instruments, generally including ammeter, voltmeter, Omgy and other functions. Compared with the pointer multimeter, the digital multimeter has been widely used for its high precision, fast speed, large input impedance, digital display, accurate reading, strong anti-interference ability and high degree of automation measurement. However, if the use of improper, it is easy to cause failure.
The troubleshooting of digital multimeter generally should start with the power supply. The troubleshooting of digital multimeter can be done in the following way.
1. Appearance inspection.
Can touch the battery, resistor, transistor, integrated block temperature rise is too high. such as the newly installed battery heating, indicating that the circuit may short-circuit. In addition, it should be observed whether the circuit disconnection, welding, mechanical damage.
2. Waveform analysis.
The voltage waveform, amplitude, period (frequency) of each key point of the circuit are observed by electronic oscilloscope. For example, if the clock oscillator is measured, if the oscillator has no output, the internal inverter is damaged or the external component can open.
3. Measuring component parameters.
For the components within the fault range, on-line measurement or off-line measurement, the parameter value should be analyzed. For on-line measurement of resistance, the influence of parallel components should be considered.
4, recessive troubleshooting.
Recessive fault refers to the failure of the fault, when the instrument is good or bad. Such failures are more complex, common causes include solder point virtual welding, loose, connectors loose, transfer switch contact bad, component performance instability, lead will be broken constantly. In addition, some external factors are involved. If the ambient temperature is too high, humidity too large or near intermittent strong interference signal and so on.
5. To detect all levels of work voltage.
Check the operating voltage of each point, and compared with normal value, first of all, we should ensure the accuracy of the reference voltage, preferably using a same model or similar digital multimeter for measurement, comparison.
Excluding the above possible reasons, the digital multimeter damage may be due to the measurement of the error caused by the file, such as in the measurement of AC mains, the selection of the measurement gear placed in the electrical barrier, in this case, once the table pen contact with the mains, instant can cause the internal components of the multimeter damage. Therefore, before using the Multimeter measurement must first check the measurement of the correct position. At the end of use, the measurement options are placed at the AC 750V or DC 1000V, so that no matter what parameters are measured in the next measurement, the digital multimeter will not be damaged.