Revealed: How to Check if SMD Resistor is Working

 In electronic circuits, SMD resistors, though small, play a vital role. Ensuring its proper functioning is the key to ensure the stable operation of the whole circuit. Today, MobikeChip will introduce you the effective methods to check whether SMD resistors are working or not. 

Appearance Inspection: The Key to Initial Judgment

First of all, the appearance of SMD resistors is the most basic step. Carefully observe the surface of the resistor to see if there are obvious signs of damage, such as scorching, cracking, discoloration, etc. A normal working resistor should be flat and smooth. The appearance of a normal working resistor should be flat, without obvious defects, and its markings are clearly recognizable. If black burn marks are found on the surface of the resistor, it is likely that the resistor has been damaged due to excessive heat generation caused by excessive current passing through it, in which case the resistor is usually no longer able to work properly.

Also, keep an eye on the soldering of the resistor. Check whether the solder joints between the pins and the circuit board are firm and rounded, and whether there is any false soldering, desoldering or short-circuiting. False soldering may lead to poor contact of the resistor, causing intermittent failure of the circuit; while short-circuiting will completely change the electrical characteristics of the circuit, triggering damage to other components or even failure of the entire circuit. Through the appearance inspection, we can initially rule out some cases where the resistor does not work due to physical damage or soldering problems, and point the way for further testing.

the multimeter measurement: a tool for accurate judgment

Multimeter is one of the core tools to detect whether the SMD resistor is working or not, and its measurement principle is based on Ohm's law. First of all, set the multimeter to resistance measurement gear, according to the nominal resistance value of the resistor to choose the appropriate range to ensure the accuracy of the measurement. Generally speaking, if you are not sure of the approximate resistance value of the resistor, you should start the measurement from a larger range first, and then gradually reduce the range.

When measuring, touch the pins of the multimeter to the two ends of the resistor. If the resistance value displayed by the multimeter is similar to the nominal value of the resistor (taking into account the precision error range of the resistor), it means that the resistor is basically working properly. For example, a resistor with a nominal value of 100Ω and an accuracy of ±5% is considered normal if its actual measured value is between 95Ω and 105Ω.

However, if the multimeter shows a resistance value of infinity, which indicates that the resistor may have been open-circuit, can not conduct electricity normally; if the displayed resistance value is much smaller than the nominal value or even close to zero, there may be a short-circuit situation, the resistor can not work properly. It should be noted that in the measurement process to ensure that the resistance and other components are not connected in parallel, otherwise it will affect the accuracy of the measurement results, resulting in misjudgment. 

Circuit Function Test: A Guarantee for Comprehensive Judgment

In addition to visual inspection and multimeter measurement, function testing of the entire circuit is an important means of determining whether the SMD resistor is working or not. Connect the circuit board containing the resistor into a normal working circuit system and observe whether the circuit can realize the expected function.

For example, in a simple LED lighting circuit, if the SMD resistor is used for current limiting, when the resistor is working properly, the LED should be able to light up normally and with moderate brightness; if the resistor is damaged, it may result in the LED not lighting up (open resistor) or over-lighting (shorted resistor) or even damage. Through actual testing of the circuit function, combined with the results of visual inspection and multimeter measurements, we can more comprehensively and accurately determine whether the SMD resistor is functioning properly in the circuit, and the impact of its operating status on the overall circuit performance.

At MobikeChip, we understand the importance of electronic component testing for circuit reliability. Through the combined use of the above three methods, you can effectively check whether SMD resistors are working or not, find and solve potential problems in time, and ensure that your electronic equipment can operate stably and efficiently. If you have any questions or need further technical support in the process of electronic component testing, please feel free to visit MobikeChip website, our professional team will be happy to serve you. 

Reprinted from:  Resistors-Manufacturers-Dealer-MobikeChip