A digital multimeter is a kind of measuring instrument that displays the measured data in digital form. The digital multimeter has the advantages of accurate reading, strong anti-interference ability, large output resistance, high measurement accuracy, and high speed. Digital multimeter in the process of use is also a certain failure, this time there is a failure, then how to discharge as soon as possible failure? Xiao Bian today to specifically introduce the digital multimeter troubleshooting method.

First, the appearance of inspection.

The temperature rise of the battery, resistor, transistor, and manifold can be touched by hand. If the newly installed battery is hot, the circuit may be short-circuited. In addition, it should also observe whether the circuit is broken, soldered, mechanical damage, etc.

Second, detect the working voltage at all levels.

Check the working voltage of each point, and compared with the normal value, we should first ensure the accuracy of the reference voltage, it is best to use a same type or similar digital multimeter to measure and compare.

Third, waveform analysis.

Observe the voltage waveform, amplitude, period (frequency) of each key point of the circuit with an electronic oscilloscope. For example, if the clock oscillator is started, the oscillation frequency is 40 kHz. If there is no output from the oscillator, the internal inverter of the TSC7106 is damaged, or the external device may be open circuit. Observe that the waveform of the {21} pin of the TSC7106 should be a 50Hz square wave. Otherwise, the internal 200 divider may be damaged.

Fourth, measuring component parameters.

For on-line measurement or off-line measurement of components within the fault range, the parameter values ​​should be analyzed. For on-line resistance measurements, the effects of the elements in parallel with it should be considered.

V. Hidden troubleshooting.

Recessive faults refer to faults that occur when the fault occurs and when the instrument is in good or bad condition. Such failures are more complex, and common causes include solder joints, solder joints, loose connectors, loose contact switches, poor component performance, and uninterrupted leads. In addition, it also includes some external factors. If the ambient temperature is too high, the humidity is too high or there are intermittent strong interference signals and so on.