Digital multimeter hidden fault troubleshooting technique
There are many types of digital multimeters, and the scope of application is also very wide, but after all, multimeters are a kind of electronic products, and there may be some minor problems during use. Here are some small troubleshooting methods.
1. Waveform analysis.
Use an electronic oscilloscope to observe the voltage waveform, amplitude, period (frequency), etc. of each key point of the circuit. For example, if the clock oscillator starts to vibrate, whether the oscillation frequency is 40kHz. If the oscillator has no output, it means that the internal inverter of TSC7106 is damaged, or the external components may be open. Observe that the waveform at pin {21} of TSC7106 should be a 50Hz square wave, otherwise, the internal 200 frequency divider may be damaged.
2. Measuring component parameters.
For components within the fault range, conduct online or offline measurements, and analyze parameter values. When measuring resistance online, the influence of components connected in parallel with it should be considered.
3. Hidden troubleshooting.
Hidden faults refer to faults that appear and disappear from time to time, and the instrument is good and bad. This kind of failure is more complicated, and the common reasons include weak welding of solder joints, looseness, looseness of connectors, poor contact of transfer switches, unstable performance of components, and continuous breakage of leads. In addition, it also includes some external factors. For example, the ambient temperature is too high, the humidity is too high, or there are intermittent strong interference signals nearby.
4. Visual inspection.
You can touch the battery, resistors, transistors, and integrated blocks to see if the temperature rise is too high. If the newly installed battery heats up, the circuit may be short-circuited. In addition, the circuit should also be observed for disconnection, desoldering, mechanical damage, etc.
5. Detect the working voltage at all levels.
Detect the working voltage of each point and compare it with the normal value. First, ensure the accuracy of the reference voltage. It is best to use a digital multimeter of the same model or similar to measure and compare.
