Digital Multimeter Repair Methods & Tips
Sensory Inspection MethodJudge the cause of failure directly through the senses. Visual inspection can reveal problems such as broken wires, cold solder joints, bridging short circuits, blown fuses, burnt components, mechanical damage, and lifted or broken copper foil on printed circuit boards. Touch can detect temperature rises in batteries, resistors, transistors, and integrated circuits, and abnormal heating causes can be identified with reference to the circuit diagram. In addition, manual checks can confirm loose components, poorly seated integrated circuit pins, and stuck selector switches; abnormal sounds and odors can also be heard and smelled.
Voltage Measurement MethodMeasure the operating voltages at key points to quickly locate faults, such as the operating voltage and reference voltage of the A/D converter.
Short-Circuit MethodAs mentioned in the A/D converter inspection methods, the short-circuit method is commonly used and is widely applied in repairing low-voltage and microelectronic instruments.
Disconnection MethodDisconnect the suspicious section from the complete or unit circuit. If the fault disappears, the problem lies in the disconnected circuit. This method is mainly suitable for short-circuit conditions.
Component Testing MethodWhen the fault has been narrowed down to a certain area or several components, test them in-circuit or off-circuit. If necessary, replace them with good components; if the fault is eliminated, the original components are defective.
Interference MethodUse human body induced voltage as an interference signal and observe changes in the LCD display. This method is often used to check whether the input circuit and display section are functioning properly.
