Troubleshooting methods for multimeters

Repair method: Find the fault from the outside to the inside, from the easy to the difficult, break the whole into parts, and focus on the breakthrough. The methods can be roughly divided into the following types: 　　

⒈ The sensory method directly judges the cause of the fault by relying on the senses. Through visual inspection, it can find out such things as broken wires, desoldering, short circuits, broken fuses, burned components, mechanical damage, copper foil lifting and breaking on printed circuits, etc.; it can touch the temperature rise of batteries, resistors, transistors, and integrated circuits, and refer to the circuit diagram to find out the cause of abnormal temperature rise. In addition, you can use your hands to check 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 whether there are any abnormal sounds or odors. 　　

⒉ The voltage measurement method measures whether the working voltage of each key point is normal, which can quickly find the fault point. For example, measuring the working voltage and reference voltage of the A/D converter. 　　

⒊ Short-circuit method: The short-circuit method mentioned above is generally used in the methods of checking A/D converters. This method is more commonly used in repairing weak current and micro-electric instruments. 　　

⒋ The circuit breaking method disconnects the suspicious part from the whole machine or unit circuit. If the fault disappears, it means that the fault is in the disconnected circuit. This method is mainly suitable for the situation where there is a short circuit in the circuit. 　　

5. Component measurement method: When the fault has been narrowed down to a certain place or several components, it can be measured online or offline. If necessary, replace it with a good component. If the fault disappears, it means that the component is broken. 　　

⒍The interference method uses the human body induced voltage as the interference signal to observe the changes in the LCD display. It is often used to check whether the input circuit and display part are intact.