The reason a multimeter can measure current, voltage, and resistance lies in its use of a sensitive galvanometer. When a small current passes through the meter, the needle will indicate a value. However, the galvanometer cannot directly handle large currents, so it is necessary to connect some resistors in parallel or series with the galvanometer … Read more
This is a new model of the Nanjing Kehua MF47-F multimeter. Upon opening the back cover, it is easy to notice that compared to the old model, the most obvious difference is that the function switch section has adopted a rotating buckle design. After a thorough examination, I recently made a few modifications to achieve … Read more
Electrical Engineering Learning Network: www.dgdqw.com Follow the official WeChat account of the Electrical Engineering Learning Network “Electrical Engineering and Electronics” to gain more experience and knowledge. The multimeter is the primary troubleshooting tool for electricians. Once accustomed to it, even when a fault occurs that could be diagnosed without a multimeter, one may feel uneasy … Read more
1. Usage of Multimeters 1. Understanding Common Symbols on Multimeters Types of electrical measurements and switch positions: ACV (or V) — AC voltage range, typically includes 2.5V, 10V, 50V, 250V, 500V, etc. DCV (or V) — DC voltage range, typically includes 0.5V, 2.5V, 10V, 50V, 250V, 500V, etc. DCmA (or mA) — DC milliamp range, … Read more
First, it is essential to develop good habits by carefully checking the multimeter for any abnormalities before use. This does not take much time but has a significant impact. For example, check for any damage to the meter, and whether the digits or needle are functioning correctly, especially when measuring high voltages. Always inspect the … Read more
What is a multimeter? A multimeter, also known as a multi-tester, volt/ohm meter, is a versatile measuring instrument that can be classified into analog and digital types. It is a multifunctional, multi-range measuring device that can generally measure DC current, DC voltage, AC current, AC voltage, resistance, and audio levels. Some models can also measure … Read more
All multimeters are equipped with a dial on the front, which not only has several scales corresponding to various measurement items but also includes various symbols, scale lines, and values, as shown in the figure. Correctly reading and understanding these symbols is fundamental to effectively using a multimeter. Letter Symbols and Their Meanings on Multimeters … Read more
2. Characteristics and Identification of Resistor Damage Many beginners often struggle with resistors when troubleshooting circuits, taking them apart and re-soldering them. In fact, after gaining some experience, understanding the characteristics of resistor damage can save a lot of unnecessary effort. Resistors are the most numerous components in electrical devices, but they are not the … Read more
1. Observation Method When we receive a circuit board for repair, the first step is to carefully observe its appearance. If the circuit board has been burned, it is crucial to check whether the power circuit is functioning correctly before powering it up, ensuring that no further damage will occur. The observation method is a … Read more
1. Fault Characteristics and Repair of Damaged Capacitors on Engineering Circuit Boards The faults caused by capacitor damage are the most common in electronic devices, especially the failure of electrolytic capacitors. The manifestations of capacitor damage include: 1. Reduced capacitance; 2. Complete loss of capacitance; 3. Leakage; 4. Short circuit. The role of capacitors in … Read more