What are the troubleshooting methods when a multimeter malfunctions?
1. Sensory method relies on sensory perception to directly determine the cause of faults. Through visual inspection, it can detect factors such as broken wires, desoldering, short circuits in grounding, broken fuse tubes, burnt components, mechanical damage, copper foil warping and breakage on printed circuits, etc; You can touch the temperature rise of the battery, resistor, transistor, and integrated block, and refer to the circuit diagram to find the cause of the abnormal temperature rise. In addition, you can also check by hand whether the components are loose, whether the integrated circuit pins are firmly inserted, and whether the conversion switch is stuck; You can hear and smell any unusual sounds or odors.
2. The voltage measurement method measures whether the working voltage of each key point is normal, which can quickly identify the fault point. Measure the operating voltage, reference voltage, etc. of the A/D converter.
3. Short circuit method is generally used in the inspection of A/D converters mentioned earlier, and it is more commonly used in repairing weak and micro electrical instruments.
4. The circuit breaking method interrupts the suspicious part from the entire machine or unit circuit. If the fault disappears, it indicates that the fault is in the disconnected circuit. This method is mainly suitable for situations where there is a short circuit in the circuit.
5. When the fault has narrowed down to one or several components, it can be measured online or offline using the component measurement method. If necessary, replace with good components. If the fault disappears, it indicates that the component is broken.
6. The interference method uses human induced voltage as an interference signal to observe the changes in the LCD display, and is commonly used to check whether the input circuit and display part are intact.
