How to judge the resistance value if the chip resistor is burned out

During the maintenance and repair of electronic equipment,Chip resistorAs a common electronic component, the stability of its performance directly affects the normal operation of the equipment. However, due to overload, short circuit or environmental factors, the patchresistanceBurning is prone to occur. Once burned out, accurately determining its resistance is critical for troubleshooting and replacement. This article will introduce in detail how to determine the resistance value after the chip resistor is burned out, to help electronic engineers and maintenance personnel improve maintenance efficiency.

1. Observe the appearance changes of the chip resistor

After the chip resistor is burned out, there will usually be obvious appearance changes, such as blackening in color, scorch marks or cracks on the surface, etc. These visual characteristics are the preliminary basis for judging whether the resistor is burned out. The degree of damage can be seen more clearly through observation with a magnifying glass or microscope, but changes in appearance do not directly reflect specific changes in resistance.

2. Use a multimeter to measure the resistance value

The most direct method is to use a digital multimeter or ohmmeter to measure the resistance of the chip resistor. Set the multimeter to the resistance setting and measure the resistance at both ends of the chip resistor. Under normal circumstances, the resistance value should be close to the nominal value; if the measured value is 0 ohms or close to a short circuit, it means that the resistor may be burned into a short circuit state; if the measured value is infinite or extremely high, it means that the resistor is open circuit or burned out.

3. Confirm the resistance range based on the circuit diagram.

Before measuring, check the circuit diagram and component list of the device to confirm the nominal resistance range of the chip resistor. The greater the deviation between the resistance value measured after burning and the nominal value, the higher the possibility of burning. Combined with the circuit diagram, it can help quickly judge the rationality of the measurement results and avoid misjudgment.

4. Measure the temperature change of the resistor

Burnt chip resistors will generate abnormal heat during operation. Use an infrared thermometer or thermal imager to measure the surface temperature of the resistor and observe whether there is abnormally high temperature. If the resistor temperature is significantly higher than the normal operating temperature, it indicates that the resistor is faulty or has an abnormal resistance value.

5. Use bridges for precise measurements

For chip resistors with smaller resistance and higher requirements, bridge equipment (such as Wheatstone bridge) can be used for more accurate resistance measurement. The electric bridge can effectively eliminate measurement errors and obtain accurate resistance data, making it easy to judge the degree of burnout.

6. Determine the resistance value based on circuit function test

Energize the circuit where the chip resistor is located and observe whether the circuit function is normal. If the circuit appears to be in abnormal working condition or does not work, use the measured resistance value to determine whether the resistor is burned out. Functional testing can help confirm the relationship between abnormal resistance and circuit faults.

7. Refer to the specifications provided by the manufacturer

Different types of chip resistors have different withstand voltage, power and resistance tolerance standards. Check the manufacturer's specifications to understand the rated parameters of the resistor, which will help determine whether the resistance change after burning is within the abnormal range.

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Determining the resistance value after the chip resistor is burned is a key step in the maintenance of electronic equipment. By observing the appearance, measuring with a multimeter, confirming with the circuit diagram, measuring the temperature, using a bridge to accurately measure, functional testing and referring to the specifications, the resistance changes of the burned chip resistor can be comprehensively and accurately judged. Mastering these methods can not only improve maintenance efficiency, but also effectively avoid misjudgments and ensure the stable operation of electronic equipment. Maintenance personnel should use it flexibly according to the specific situation to ensure accurate diagnosis and treatment of chip resistor faults.