How to use a multimeter to measure circuit faults
Use the ohm x1 file to measure the two ends of the line. If the resistance is close to zero, it is a short circuit. If there is a certain amount of resistance (according to the load in the line), it is not a short circuit. When the voltage is constant, the smaller the resistance, the more current flow The greater the current flowing through the line. Use the ohm 1k file or 10k file to measure the two ends of the line. If the resistance is infinite, it is an open circuit.
How to use a digital multimeter to check the line fault point
1. 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.
2. 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 is oscillating, if there is no output from the oscillator, it means that the internal inverter is damaged, or the external components may be open.
3. 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.
4. 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, loose 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.
5. Detect the working voltage at all levels.
Detect the working voltage of each point and compare it with the normal value,
First of all, the accuracy of the reference voltage should be guaranteed. It is best to use a digital multimeter of the same model or similar to measure and compare.
