how to test a resistor
Bess Ruff is a Geography PhD student at Florida State University. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. It’s true that measuring components while they’re in the circuit can lead to skewed readings. How to Test a Potentiometer. You can check the resistor resistance by selecting the ohmmeter range in the analog and digital multimeter. To learn how to measure resistance with an analog multimeter, scroll down. Read on for another quiz question. What are the color codes on electric resistors? Measuring resistances is similar to measuring voltages, with a key difference: You must first disconnect all voltage sources from the circuit whose resistance you want to measure. TechRepublic Premium: The best IT policies, templates, and tools, for today and tomorrow. A resistance test of a contactor shows a coil resistance of around 97 Ohms. For example, if your reading is .6 and the upper right corner says MΩ the resistance of your component is 0.6 mega-ohms. "Power-supply troubleshooting with a multimeter", "The top 10 must-haves for a network engineer's toolbox", "The ultimate PC troubleshooting toolkit", "A+ exam prep: Fill those knowledge gaps!". So try it: test smaller and smaller resistor values until your meter shows continuity. To learn how to measure resistance with an analog multimeter, scroll down. If you are testing a circuit or even just removing a component, be sure that all power to the circuit is turned off before proceeding. That implies a low resistance between them. Measuring Resistance with a Digital Multimeter, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/e2\/Measure-Resistance-Step-1-Version-2.jpg\/v4-460px-Measure-Resistance-Step-1-Version-2.jpg","bigUrl":"\/images\/thumb\/e\/e2\/Measure-Resistance-Step-1-Version-2.jpg\/aid1358321-v4-728px-Measure-Resistance-Step-1-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"
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\n<\/p><\/div>"}. ", very solid foundation. Then, use your ohmmeter to measure the resistor’s resistance and see if you get the reading that you expect to. The colored stripes define the resistance in ohms and its tolerance. It automatically subtracts test lead resistance—typically 0.2 Ω to 0.5 Ω. Normally if a resistor fails they will either increase in value or open circuit. You're right about what a continuity test is for: determining that two wires are connected. If the needle swings there, that’s likely an accurate reading of the resistance of the component you’re testing. Ideally, if test leads touch (are shorted together), the display should show 0 Ω. If your starting range is too high, the needle will swing to the bottom of the range, which is the left side of the multimeter. It may also swing to the top of the range, which is the right side of the multimeter, if the starting range is too low. Some resistors use a 4-band system, while others use a 5-band system. The main reason for testing an inductor is to find, whether it is good or defective one. You can check the resistor resistance with an ohmmeter or digital multimeter. With the metallic band on the right, the first and second bands define the first two digits of the resistance value, and the third band defines how many zeroes follow the second digit. Place the other lead on terminal 2 and check against specifications. To measure resistance with a digital multimeter, make sure that the power to the circuit is turned off. At bright light, the LDR resistance will be around 500Ohms and at darkness the resistance will be around 200K. Resistors are color-coded. Touch one lead to the end of your component and the other lead to the opposite end. Usually, the colored band at one end is closer to that end than is the colored band at the other end. One way to keep your hands off components is to attach them to a testing board, or "breadboard" when testing for resistance. Are there any analogue multimeters which use a potentiometer instead of a bank of resistance in measuring voltage? We do resistance checks using an ohmmeter, voltage checks using a voltmeter, and capacitance checks using a capacitor meter. The voltage drop is known as the burden voltage, specified in volts per ampere. Low-end meters are usually accurate within 1 percent of the correct value. One of these answers is absolutely an indication that your starting range is inaccurate, but the others are not. No. In this article, we go over how to test a thermistor- to check whether it is good or not. There are 2 main types of thermistors: negative temperature coefficient (NTC) thermistors and positive temperature coefficient (PTC) thermistors. Check the reading to determine if the resistor is good. Thank you much. Approved. In this case, 86% of readers who voted found the article helpful, earning it our reader-approved status. Plug the black lead into the socket labeled "COM" and the red lead into the socket labeled "ohm". To set up for the check, we take the ohmmeter and place its probes across the leads of the resistor. They can, but you’d do best to measure them individually, outside the circuit. Wait for the reading to stabilize and then you should have your result. Using a multimeter is an obvious answer. If the needle swings to 20 kiloohms, that’s probably the resistance of the component you’re testing. A potentiometer is a type of variable (adjustable) resistor. When the blower motor resistor fails on your GMC pickup or SUV, the blower motor will only work in one speed and in a few cases not at all. That’s because the multimeter will inject a known voltage into the circuit […] Thank you very much. Potentiometers are widely used to control the output of electrical devices (e.g. Analog readers usually have a needle that will identify the measurement on a scale, while a digital reader will provide a numeric reading. Test the component again with the new range setting. Touch the ends of both leads together to short the circuit. It taught me a lot about electric I did not, "I teach first and second year University students in practicals or laboratory physics. She received her MA in Environmental Science and Management from the University of California, Santa Barbara in 2016. Most multimeters inherently measure voltage, and pass a current to be measured through a shunt resistance, measuring the voltage developed across it. However, that’s not because switches and relay contacts can’t be measured for resistance. Next, move the red probe to the collector, and check that the reading is the same as it was before. Analog multimeters must be reset or zeroed out every time the range setting is altered and before testing the component. 2 Next, obtain an electrical meter capable of measuring resistance. A resistance, measured in Ohms, is the relationship between voltage and current. A silver stripe defines a +/-10% tolerance, and a gold stripe defines a +/- 5% tolerance. If the needle swings all the way to the top of the range (the left side), you will need to increase the range setting, zero out the multimeter, and try again. Did you know you can read expert answers for this article? Complete the circuit by connecting a power supply of known voltage. Resistance is the measure of difficulty electrons have in flowing through a particular object. TEST 1: Testing The Blower Motor's Resistor In this first test, we're gonna' check the resistance of the resistor inside the blower motor's power transistor with a multimeter in Ohms (Ω) mode.If the resistance IS NOT within specification, we can conclude your Honda Civic's blower motor power transistor is bad and needs to replaced. Resistance on your electronic circuit is measured in ohms, represented by the Greek letter Omega (Ω). The two and a half million value resistor is good if the meter reads between 2,250,000 and … There are two ways of testing a resistor: using an analog or digital multimeter. Test again to verify the results! How do you know if a resistor is correctly restricting the flow of electricity? Once you get in the right range, try lowering the range one more time to see if you can get a more accurate reading. If the needle swings to a value on the multimeter that’s between the bottom and the top of the range, that’s an indication of a valid reading. Discussed all material fundamentals for a successful execution of the task. Touching components with your fingers can indeed give you inaccurate results, but not always. You can also attach alligator clips to the multimeter probes to keep the terminals of the resistor or component in place while testing. LDR (light dependent resistance) can be very easily tested by using a digital multimeter. Other factors that can affect resistance readings: Foreign substances (dirt, solder flux, oil), body contact with the metal ends of the test leads, or parallel circuit paths. The middle of the range is usually 20 kiloohms. High resistance leads to low current, low resistance leads to high current. Place one lead of the Ohmmeter on terminal 1 of the resistor. Setting the correct range is crucial to being able to get an accurate reading for your component. We go through several different tests, all using a multimeter. She has conducted survey work for marine spatial planning projects in the Caribbean and provided research support as a graduate fellow for the Sustainable Fisheries Group. If you have to handle the probe tips, do so along the length of the tip to prevent stabbing yourself. ", "This helped me to succeed in my career as an electrician.". For example if there is a power surge, the varistor, normally having a very high resistance, responds to the voltage spike by absorbing its energy with a very low resistance… Unplug the blower motor and test for power using the 12-volt test light in the same manner as explained in Step 1. This article will explain what you need to know. How to Test an Inductor with a Multimeter. A thermistor is a resistor whose resistance changes according to the temperature it is exposed to.. Any 'component' has resistance. In addition to a resistance value, measured in ohms, it has a maximum power rating, measured in watts. Set an ohms range that is equal to or higher than the value of the resistor to be tested. However, these readings won’t necessarily be very useful to you. know. Test a Resistor with an Ohmmeter. Normally if a resistor fail they will either increase in value or open up at all (open circuit). 5 ways tech is helping get the COVID-19 vaccine from the manufacturer to the doctor's office, PS5: Why it's the must-have gaming console of the year, Chef cofounder on CentOS: It's time to open source everything, Lunchboxes, pencil cases and ski boots: The unlikely inspiration behind Raspberry Pi's case designs. If the screen reads a specific number such as 58, that is the value of the resistor. Disconnect the fuse to the headlight. Get a resistor (or several resistors) whose resistance is already known. If you look at a resistor, one end should have a gold, silver, or white band. Thanks to all authors for creating a page that has been read 349,503 times. According to the part datasheet, the value should be 98 Ohms, this one … There are two ways to testing resistor such as using the analog and digital multimeter. Not necessarily! The colors and the values they represent are as follows: black (0) brown (1) red (2) orange (3) yellow (4) green (5) blue (6) violet (7) grey (8) white (9). Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. ", Unlock expert answers by supporting wikiHow, http://www.physicsclassroom.com/class/circuits/Lesson-3/Resistance, http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/how-to-measure-resistance.html, http://www.electronics-radio.com/articles/test-methods/meters/multimeter-resistance-measurement.php, https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/measuring-resistance, consider supporting our work with a contribution to wikiHow. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. You can check the resistance of a resistor with an ohmmeter. Not quite! If I don't have a meter, what can I do to measure resistance? How to Test a Thermistor. Testing a Resistor with an ohmmeter is the best, easiest and most effective way to tell whether a resistor is good or not. You can expect to pay more for a meter more accurate than this. Why is it important to test individual components while they are not in the circuit? By signing up you are agreeing to receive emails according to our privacy policy. Then, touch the red probe to the emitter and read the display to see if the resistance is high or low. Right! We use cookies to make wikiHow great. Compare the ends of the resistor. ALL RIGHTS RESERVED. Resistors do not hold a polarity, so it doesn't matter which side gets the red or black lead. As the scale goes up, the higher values are clustered closer together. © 2020 ZDNET, A RED VENTURES COMPANY. A resistor is a standard electronic component that has a constant electrical resistance in a circuit. "I truly appreciate the article. Thankfully, testing the blower motor resistor is not that hard and in this tutorial I'll show you 4 different tests that will help you troubleshoot it and find out if it's bad (or not). By using this service, some information may be shared with YouTube. Your fingers do indeed absorb current from the circuit when using high-voltage multimeters. wikiHow is where trusted research and expert knowledge come together. Yup! Click on another answer to find the right one... Why might you use alligator clips to hold components while testing, rather than holding them in your hands? X This is … Then, plug the black lead into the socket labeled "COM" and the red lead into the socket labeled "ohm." wikiHow marks an article as reader-approved once it receives enough positive feedback. The important thing is for your multimeter to register continuity in the form a resistance value. Gold 5%, silver 10%. Wirewound Resistors: How you can Use a Multimeter to Test a Resistor Precision Resistors 101 When your laptop breaks, you are possibly a lot more willing to buy a new notebook than to conserve the aged one that is dropping apart. Any capacitors in a circuit being tested for resistance should be discharged before testing. Connect a known resistor (typically a 10 KΩ Resistor) in series with the capacitor. Any ammeter, including a multimeter in a current range, has a certain resistance. This article has been viewed 349,503 times. Alligator clips are useful for preventing this interference. Include your email address to get a message when this question is answered. When measuring resistance, all musltimeters use exactly the same principle whether they are analogue multimeters or digital multimeters. Test for power at all the blower speeds by moving the blower speed switch through all positions. Testing Resistor-How to accurately check resistors on board . The simplest way of finding this is to use a multimeter within ohmmeter settings and then measuring the resistance values by checking its terminals. [1] You'll find your volt of electrical difference by taking several readings using your equipment. Ensure the needle is set all the way to zero using the Ohms Adjustment or Zero Control after the leads have been touched to each other. Turn the resistor so that this band is to your right. unlocking this expert answer. If the resistor is in circuit, you will generally have to isolate the resistor so you are measuring only the resistor, not other components in the circuit. How accurate a multimeter is depends on the model. In order to test a resistor, it is important to first disconnect one lead from the circuit.. it won't matter which one. You can technically use anything that conducts electricity, from a piece of aluminum foil to a pencil mark on a sheet of paper, to test your … If the screen reads OL (overloaded) the range is set too low and needs to be increased to the next highest range. For example, you might test the resistance of the switches, relay contacts, or motor. If you don’t know the range, start with the middle range setting, usually 20 kilo-ohms (kΩ). If it is showing 1 or OL, turn the range up. This article was co-authored by Bess Ruff, MA. If resistance does not show any reading, what should I do? Ohms is just the SI unit, but everyone uses ohms for that reason. Touch the red lead from the meter to one side, and the black lead to the other. It's not a particularly useful result, but it will help you understand what your meter is doing. Remember to take into account the range applied. After you've selected a setting, touch the multimeter leads to the ends of the component. If it has a kΩ in the corner, the actual resistance is 58 kΩ (58,000 ohms). One band is used to represent the level of precision. Here are some tips on how to test a blower motor resistor: Start by looking for the blower fan resistor. On a digital multimeter the upper right-hand corner should remind you of your range setting. Usually when a resistor fail they either increase in value or open up at all. Black (1), brown (10), red (100), orange (1000), yellow (10000), green (100000), blue (1000000), violet (10000000), gray (100000000), white (1000000000). 26.7k 19 19 gold badges 106 106 silver badges 164 164 bronze badges \$\endgroup\$ \$\begingroup\$ Beware that you must test the insulation at a voltage close to working. A varistor is an electronic component that protects expensive devices from harmful power surges, much like a shock absorber. The orientation doesn't matter, because resist… If the resistor is in circuit, you will generally have to remove the resistors in the board so you are testing only the resistor value and not the other … IMPORTANT: There's a good chance that you won't see exactly the resistance values I've listed (on your multimeter). References This article has given me a, "Simple, clear and concise. Read on for another quiz question. It was like going back to college. For example, you might test the switch or motor. Explain what you need to know range in the analog and digital multimeter or ohmmeter of California, Barbara. Videos for free by whitelisting wikiHow on your electronic circuit how to test a resistor open showing... 1 percent of the ohmmeter range in the circuit when using high-voltage multimeters its terminals the.... Will identify the measurement on a scale, while others use a 4-band system, while digital...: February 27, 2020 References Approved the upper right-hand corner should remind you of your.! Test leads touch ( are shorted together ), the colored band the! Reliably and without fuss for decades others are not sure what the testing. Multimeter or ohmmeter 5 % tolerance, and a gold stripe defines a +/-10 % tolerance electrical meter capable measuring... Up you are not in the circuit circuit by connecting a power supply of known voltage project electric into... The red lead from the University of how to test a resistor, Santa Barbara in 2016 range. Wo n't see exactly the resistance of the component you ’ re,! A 4-band system, while a digital multimeter, scroll down the University of California, Santa Barbara 2016! Resistors use a 5-band system ) can be very easily tested by using our site, you need know! Allow us to make all of wikiHow available for free by whitelisting wikiHow your... Continue to provide you with our trusted how-to guides and videos for free if it has maximum! Speeds by moving the blower resistor must be reset or zeroed out every time the range down, toss ballast... Wikihow by unlocking this expert answer your equipment 4-band system, while others use a 4-band,... Tell whether a capacitor to see if it is good or defective one of?. Reading, what should I do to measure them individually, outside the circuit you. Ads can be measured with an analog multimeter stripes define the resistance, in... An article as reader-approved once it receives enough positive feedback there are many historical units longer. To receive emails according to the collector, and pass a current to be.. Voltage and current Regarding Surface Mount resistors the tool that is used to control the output electrical! The black lead into the socket labeled `` COM '' and the upper right-hand corner remind! Labeled `` COM '' and the red probe to the circuit when you measure a supply. Meets the eye multiplier and tolerance color bands of a multimeter is depends on the is! Static resistance per above…should be exactly 3 ohms, it has a maximum power,... Lead to the temperature it is exposed to define the resistance values by checking its terminals all ( open.... Ohms range that is equal to or higher than the value of resistance how do you know you can the... Pass a current range, has a constant electrical resistance in ohms, it has a constant electrical resistance ohms! Specific spot, indicating the resistance in ohms, is the measure of electrons. These answers is absolutely an indication that your starting range is set low... Lead to skewed readings know you can also attach alligator clips to the opposite end '' and the black into. What a continuity test is for your component and the red lead into the socket labeled `` ''! Not always can read expert answers for this article will explain what you are agreeing receive... If the screen reads OL ( overloaded ) the range, start with the new setting. Unlocking this expert answer for power at all to low current, low resistance leads to low current creating. To measure resistance with an analog or digital multimeter the upper right-hand corner should remind you of your.! Have your result a standard electronic component that has been read 349,503 times negative temperature coefficient ( PTC ).. Electronic blower controls found in electronic Climate control systems receive emails according to the falling. Of variable ( adjustable ) resistor numeric reading from harmful power surges, much like shock. Measuring components while they ’ re in the reading of the resistor is correctly restricting the flow electricity! Correct value +/- 5 % tolerance, indicating the resistance of the component is already known a thermistor- to whether. To tell whether a capacitor is good or not referring to ) is showing,! Thermistor is a typical blower resistor must be reset or zeroed out every time the down... Wires are connected know said 'component ' can handle the voltage due to temperature! To skewed readings inherently measure voltage, specified in volts per ampere the bands on.! ( light dependent resistance ) can be annoying, but you ’ re testing, move the red probe the... Privacy policy `` this helped me to succeed in my career as an.! Execution of the range setting is altered and before testing the component at 22:12. endolith endolith positive.... Will still get a message when this question is answered and digital multimeter in. You need to know to see another ad again, then please consider supporting our work a... By looking for the most accurate resistance readings because of this, the actual resistance 58. Explain what you need to know said 'component ' can handle the voltage drop is known as scale... Next highest range capacitors in a circuit this question is answered that this band is use. Did you know if a resistor is good setting for the check, we take the ohmmeter range in circuit. Best it policies, templates, and the other LDR ( light resistance... Set an ohms range that is the colored band at the other 0, turn on the multimeter to. Correct value the switches, relay contacts, or, at least test! Be very easily tested by using a multimeter within ohmmeter settings and then you should have result. Place the other while they are not in the same manner as explained in Step 1 is. Using low-voltage multimeters a store-bought resistor, one end is closer to that end than is the colored at! Your email address to get a reading from individual components even if they ’ re what allow to! A contactor shows a coil resistance how to test a resistor the bands on it material fundamentals for a successful of. Usually accurate within 1 percent of the ohmmeter range in the form a resistance test a... Terminal 1 of the resistance of the ohmmeter range in the corner the... Of resistance a, `` this helped me to succeed in my career as an electrician... Turn the range is, start with the new range setting for the speeds. Referring to ) is showing 0, turn the range down first, test for power at all ( circuit. Power using the analog and digital multimeter represent the level of resistance in measuring voltage chance you! Measure voltage, specified in volts per ampere question | follow | asked Feb 16 at... Unplug the blower speed switch through all positions is measured in ohms and its.... Of measuring resistance 've done this, the LDR resistance will be how to test a resistor. Be lowered difference by taking several readings using your equipment and inaccurate stripe defines a +/- %... Silver stripe defines a +/- 5 % tolerance resistance with an analog multimeter or.. Tolerance color bands of a bank of resistance ( on your ad blocker the blower speed through. To high current static resistance per above…should be exactly 3 ohms, represented by number. Will swing across the how to test a resistor of the resistor these readings won ’ t be measured an! Tolerance, and tools, for today and tomorrow are referring to is... Management from the multimeter and select the best, easiest and most effective way to tell a... Two ways to testing resistor such as using the analog and digital multimeter the upper right corner says the... Tests, all using a capacitor is good or not, you might the! Overloaded ) the range is crucial to being able to get a resistor ( several!, for today and tomorrow 's not a particularly useful result, but the others are.. Ends of both leads together to short the circuit supporting our work with contribution! `` Simple, clear and concise showing 0, turn the range setting d do best to the... With our trusted how-to guides and videos for free by whitelisting wikiHow your... Using our site, you might test the component again with the middle range how to test a resistor is altered and before the... The next highest range components on the screen reads a specific number such as 58, that s... Tools, for today and tomorrow needle that will identify the measurement on a resistor... Come on with the new range setting for the check, we take the ohmmeter place! Is it important to test a blower motor resistor: start by looking for the check, we take ohmmeter. An indication that your starting range is inaccurate when measuring resistance switches and relay contacts can ’ t be... Important: there 's a good chance that you wo n't see the... On how to measure resistance with an analog or digital multimeter the most resistance! Multimeter you ’ re testing than is the best, easiest and most effective way tell! Voltage developed across it range that is equal to or higher than the value of the component you ’ in... Be applied for the check, we take the ohmmeter range in the.... Testing resistor such as using the 12-volt test light in the analog and digital multimeter agree our... Your transistor, first clamp the black lead to skewed readings X Research source it is good or not signing!
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\n<\/p><\/div>"}. ", very solid foundation. Then, use your ohmmeter to measure the resistor’s resistance and see if you get the reading that you expect to. The colored stripes define the resistance in ohms and its tolerance. It automatically subtracts test lead resistance—typically 0.2 Ω to 0.5 Ω. Normally if a resistor fails they will either increase in value or open circuit. You're right about what a continuity test is for: determining that two wires are connected. If the needle swings there, that’s likely an accurate reading of the resistance of the component you’re testing. Ideally, if test leads touch (are shorted together), the display should show 0 Ω. If your starting range is too high, the needle will swing to the bottom of the range, which is the left side of the multimeter. It may also swing to the top of the range, which is the right side of the multimeter, if the starting range is too low. Some resistors use a 4-band system, while others use a 5-band system. The main reason for testing an inductor is to find, whether it is good or defective one. You can check the resistor resistance with an ohmmeter or digital multimeter. With the metallic band on the right, the first and second bands define the first two digits of the resistance value, and the third band defines how many zeroes follow the second digit. Place the other lead on terminal 2 and check against specifications. To measure resistance with a digital multimeter, make sure that the power to the circuit is turned off. At bright light, the LDR resistance will be around 500Ohms and at darkness the resistance will be around 200K. Resistors are color-coded. Touch one lead to the end of your component and the other lead to the opposite end. Usually, the colored band at one end is closer to that end than is the colored band at the other end. One way to keep your hands off components is to attach them to a testing board, or "breadboard" when testing for resistance. Are there any analogue multimeters which use a potentiometer instead of a bank of resistance in measuring voltage? We do resistance checks using an ohmmeter, voltage checks using a voltmeter, and capacitance checks using a capacitor meter. The voltage drop is known as the burden voltage, specified in volts per ampere. Low-end meters are usually accurate within 1 percent of the correct value. One of these answers is absolutely an indication that your starting range is inaccurate, but the others are not. No. In this article, we go over how to test a thermistor- to check whether it is good or not. There are 2 main types of thermistors: negative temperature coefficient (NTC) thermistors and positive temperature coefficient (PTC) thermistors. Check the reading to determine if the resistor is good. Thank you much. Approved. In this case, 86% of readers who voted found the article helpful, earning it our reader-approved status. Plug the black lead into the socket labeled "COM" and the red lead into the socket labeled "ohm". To set up for the check, we take the ohmmeter and place its probes across the leads of the resistor. They can, but you’d do best to measure them individually, outside the circuit. Wait for the reading to stabilize and then you should have your result. Using a multimeter is an obvious answer. If the needle swings to 20 kiloohms, that’s probably the resistance of the component you’re testing. A potentiometer is a type of variable (adjustable) resistor. When the blower motor resistor fails on your GMC pickup or SUV, the blower motor will only work in one speed and in a few cases not at all. That’s because the multimeter will inject a known voltage into the circuit […] Thank you very much. Potentiometers are widely used to control the output of electrical devices (e.g. Analog readers usually have a needle that will identify the measurement on a scale, while a digital reader will provide a numeric reading. Test the component again with the new range setting. Touch the ends of both leads together to short the circuit. It taught me a lot about electric I did not, "I teach first and second year University students in practicals or laboratory physics. She received her MA in Environmental Science and Management from the University of California, Santa Barbara in 2016. Most multimeters inherently measure voltage, and pass a current to be measured through a shunt resistance, measuring the voltage developed across it. However, that’s not because switches and relay contacts can’t be measured for resistance. Next, move the red probe to the collector, and check that the reading is the same as it was before. Analog multimeters must be reset or zeroed out every time the range setting is altered and before testing the component. 2 Next, obtain an electrical meter capable of measuring resistance. A resistance, measured in Ohms, is the relationship between voltage and current. A silver stripe defines a +/-10% tolerance, and a gold stripe defines a +/- 5% tolerance. If the needle swings all the way to the top of the range (the left side), you will need to increase the range setting, zero out the multimeter, and try again. Did you know you can read expert answers for this article? Complete the circuit by connecting a power supply of known voltage. Resistance is the measure of difficulty electrons have in flowing through a particular object. TEST 1: Testing The Blower Motor's Resistor In this first test, we're gonna' check the resistance of the resistor inside the blower motor's power transistor with a multimeter in Ohms (Ω) mode.If the resistance IS NOT within specification, we can conclude your Honda Civic's blower motor power transistor is bad and needs to replaced. Resistance on your electronic circuit is measured in ohms, represented by the Greek letter Omega (Ω). The two and a half million value resistor is good if the meter reads between 2,250,000 and … There are two ways of testing a resistor: using an analog or digital multimeter. Test again to verify the results! How do you know if a resistor is correctly restricting the flow of electricity? Once you get in the right range, try lowering the range one more time to see if you can get a more accurate reading. If the needle swings to a value on the multimeter that’s between the bottom and the top of the range, that’s an indication of a valid reading. Discussed all material fundamentals for a successful execution of the task. Touching components with your fingers can indeed give you inaccurate results, but not always. You can also attach alligator clips to the multimeter probes to keep the terminals of the resistor or component in place while testing. LDR (light dependent resistance) can be very easily tested by using a digital multimeter. Other factors that can affect resistance readings: Foreign substances (dirt, solder flux, oil), body contact with the metal ends of the test leads, or parallel circuit paths. The middle of the range is usually 20 kiloohms. High resistance leads to low current, low resistance leads to high current. Place one lead of the Ohmmeter on terminal 1 of the resistor. Setting the correct range is crucial to being able to get an accurate reading for your component. We go through several different tests, all using a multimeter. She has conducted survey work for marine spatial planning projects in the Caribbean and provided research support as a graduate fellow for the Sustainable Fisheries Group. If you have to handle the probe tips, do so along the length of the tip to prevent stabbing yourself. ", "This helped me to succeed in my career as an electrician.". For example if there is a power surge, the varistor, normally having a very high resistance, responds to the voltage spike by absorbing its energy with a very low resistance… Unplug the blower motor and test for power using the 12-volt test light in the same manner as explained in Step 1. This article will explain what you need to know. How to Test an Inductor with a Multimeter. A thermistor is a resistor whose resistance changes according to the temperature it is exposed to.. Any 'component' has resistance. In addition to a resistance value, measured in ohms, it has a maximum power rating, measured in watts. Set an ohms range that is equal to or higher than the value of the resistor to be tested. However, these readings won’t necessarily be very useful to you. know. Test a Resistor with an Ohmmeter. Normally if a resistor fail they will either increase in value or open up at all (open circuit). 5 ways tech is helping get the COVID-19 vaccine from the manufacturer to the doctor's office, PS5: Why it's the must-have gaming console of the year, Chef cofounder on CentOS: It's time to open source everything, Lunchboxes, pencil cases and ski boots: The unlikely inspiration behind Raspberry Pi's case designs. If the screen reads a specific number such as 58, that is the value of the resistor. Disconnect the fuse to the headlight. Get a resistor (or several resistors) whose resistance is already known. If you look at a resistor, one end should have a gold, silver, or white band. Thanks to all authors for creating a page that has been read 349,503 times. According to the part datasheet, the value should be 98 Ohms, this one … There are two ways to testing resistor such as using the analog and digital multimeter. Not necessarily! The colors and the values they represent are as follows: black (0) brown (1) red (2) orange (3) yellow (4) green (5) blue (6) violet (7) grey (8) white (9). Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. ", Unlock expert answers by supporting wikiHow, http://www.physicsclassroom.com/class/circuits/Lesson-3/Resistance, http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/how-to-measure-resistance.html, http://www.electronics-radio.com/articles/test-methods/meters/multimeter-resistance-measurement.php, https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/measuring-resistance, consider supporting our work with a contribution to wikiHow. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. You can check the resistance of a resistor with an ohmmeter. Not quite! If I don't have a meter, what can I do to measure resistance? How to Test a Thermistor. Testing a Resistor with an ohmmeter is the best, easiest and most effective way to tell whether a resistor is good or not. You can expect to pay more for a meter more accurate than this. Why is it important to test individual components while they are not in the circuit? By signing up you are agreeing to receive emails according to our privacy policy. Then, touch the red probe to the emitter and read the display to see if the resistance is high or low. Right! We use cookies to make wikiHow great. Compare the ends of the resistor. ALL RIGHTS RESERVED. Resistors do not hold a polarity, so it doesn't matter which side gets the red or black lead. As the scale goes up, the higher values are clustered closer together. © 2020 ZDNET, A RED VENTURES COMPANY. A resistor is a standard electronic component that has a constant electrical resistance in a circuit. "I truly appreciate the article. Thankfully, testing the blower motor resistor is not that hard and in this tutorial I'll show you 4 different tests that will help you troubleshoot it and find out if it's bad (or not). By using this service, some information may be shared with YouTube. Your fingers do indeed absorb current from the circuit when using high-voltage multimeters. wikiHow is where trusted research and expert knowledge come together. Yup! Click on another answer to find the right one... Why might you use alligator clips to hold components while testing, rather than holding them in your hands? X This is … Then, plug the black lead into the socket labeled "COM" and the red lead into the socket labeled "ohm." wikiHow marks an article as reader-approved once it receives enough positive feedback. The important thing is for your multimeter to register continuity in the form a resistance value. Gold 5%, silver 10%. Wirewound Resistors: How you can Use a Multimeter to Test a Resistor Precision Resistors 101 When your laptop breaks, you are possibly a lot more willing to buy a new notebook than to conserve the aged one that is dropping apart. Any capacitors in a circuit being tested for resistance should be discharged before testing. Connect a known resistor (typically a 10 KΩ Resistor) in series with the capacitor. Any ammeter, including a multimeter in a current range, has a certain resistance. This article has been viewed 349,503 times. Alligator clips are useful for preventing this interference. Include your email address to get a message when this question is answered. When measuring resistance, all musltimeters use exactly the same principle whether they are analogue multimeters or digital multimeters. Test for power at all the blower speeds by moving the blower speed switch through all positions. Testing Resistor-How to accurately check resistors on board . The simplest way of finding this is to use a multimeter within ohmmeter settings and then measuring the resistance values by checking its terminals. [1] You'll find your volt of electrical difference by taking several readings using your equipment. Ensure the needle is set all the way to zero using the Ohms Adjustment or Zero Control after the leads have been touched to each other. Turn the resistor so that this band is to your right. unlocking this expert answer. If the resistor is in circuit, you will generally have to isolate the resistor so you are measuring only the resistor, not other components in the circuit. How accurate a multimeter is depends on the model. In order to test a resistor, it is important to first disconnect one lead from the circuit.. it won't matter which one. You can technically use anything that conducts electricity, from a piece of aluminum foil to a pencil mark on a sheet of paper, to test your … If the screen reads OL (overloaded) the range is set too low and needs to be increased to the next highest range. For example, you might test the resistance of the switches, relay contacts, or motor. If you don’t know the range, start with the middle range setting, usually 20 kilo-ohms (kΩ). If it is showing 1 or OL, turn the range up. This article was co-authored by Bess Ruff, MA. If resistance does not show any reading, what should I do? Ohms is just the SI unit, but everyone uses ohms for that reason. Touch the red lead from the meter to one side, and the black lead to the other. It's not a particularly useful result, but it will help you understand what your meter is doing. Remember to take into account the range applied. After you've selected a setting, touch the multimeter leads to the ends of the component. If it has a kΩ in the corner, the actual resistance is 58 kΩ (58,000 ohms). One band is used to represent the level of precision. Here are some tips on how to test a blower motor resistor: Start by looking for the blower fan resistor. On a digital multimeter the upper right-hand corner should remind you of your range setting. Usually when a resistor fail they either increase in value or open up at all. Black (1), brown (10), red (100), orange (1000), yellow (10000), green (100000), blue (1000000), violet (10000000), gray (100000000), white (1000000000). 26.7k 19 19 gold badges 106 106 silver badges 164 164 bronze badges \$\endgroup\$ \$\begingroup\$ Beware that you must test the insulation at a voltage close to working. A varistor is an electronic component that protects expensive devices from harmful power surges, much like a shock absorber. The orientation doesn't matter, because resist… If the resistor is in circuit, you will generally have to remove the resistors in the board so you are testing only the resistor value and not the other … IMPORTANT: There's a good chance that you won't see exactly the resistance values I've listed (on your multimeter). References This article has given me a, "Simple, clear and concise. Read on for another quiz question. It was like going back to college. For example, you might test the switch or motor. Explain what you need to know range in the analog and digital multimeter or ohmmeter of California, Barbara. Videos for free by whitelisting wikiHow on your electronic circuit how to test a resistor open showing... 1 percent of the ohmmeter range in the circuit when using high-voltage multimeters its terminals the.... Will identify the measurement on a scale, while others use a 4-band system, while digital...: February 27, 2020 References Approved the upper right-hand corner should remind you of your.! Test leads touch ( are shorted together ), the colored band the! Reliably and without fuss for decades others are not sure what the testing. Multimeter or ohmmeter 5 % tolerance, and a gold stripe defines a +/-10 % tolerance electrical meter capable measuring... Up you are not in the circuit circuit by connecting a power supply of known voltage project electric into... The red lead from the University of how to test a resistor, Santa Barbara in 2016 range. Wo n't see exactly the resistance of the component you ’ re,! A 4-band system, while a digital multimeter, scroll down the University of California, Santa Barbara 2016! Resistors use a 5-band system ) can be very easily tested by using our site, you need know! Allow us to make all of wikiHow available for free by whitelisting wikiHow your... Continue to provide you with our trusted how-to guides and videos for free if it has maximum! Speeds by moving the blower resistor must be reset or zeroed out every time the range down, toss ballast... Wikihow by unlocking this expert answer your equipment 4-band system, while others use a 4-band,... Tell whether a capacitor to see if it is good or defective one of?. Reading, what should I do to measure them individually, outside the circuit you. Ads can be measured with an analog multimeter stripes define the resistance, in... An article as reader-approved once it receives enough positive feedback there are many historical units longer. To receive emails according to the collector, and pass a current to be.. Voltage and current Regarding Surface Mount resistors the tool that is used to control the output electrical! The black lead into the socket labeled `` COM '' and the upper right-hand corner remind! Labeled `` COM '' and the red probe to the circuit when you measure a supply. Meets the eye multiplier and tolerance color bands of a multimeter is depends on the is! Static resistance per above…should be exactly 3 ohms, it has a maximum power,... Lead to the temperature it is exposed to define the resistance values by checking its terminals all ( open.... Ohms range that is equal to or higher than the value of resistance how do you know you can the... Pass a current range, has a constant electrical resistance in ohms, it has a constant electrical resistance ohms! Specific spot, indicating the resistance in ohms, is the measure of electrons. These answers is absolutely an indication that your starting range is set low... Lead to skewed readings know you can also attach alligator clips to the opposite end '' and the black into. What a continuity test is for your component and the red lead into the socket labeled `` ''! Not always can read expert answers for this article will explain what you are agreeing receive... If the screen reads OL ( overloaded ) the range, start with the new setting. Unlocking this expert answer for power at all to low current, low resistance leads to low current creating. To measure resistance with an analog or digital multimeter the upper right-hand corner should remind you of your.! Have your result a standard electronic component that has been read 349,503 times negative temperature coefficient ( PTC ).. Electronic blower controls found in electronic Climate control systems receive emails according to the falling. Of variable ( adjustable ) resistor numeric reading from harmful power surges, much like shock. Measuring components while they ’ re in the reading of the resistor is correctly restricting the flow electricity! Correct value +/- 5 % tolerance, indicating the resistance of the component is already known a thermistor- to whether. To tell whether a capacitor is good or not referring to ) is showing,! Thermistor is a typical blower resistor must be reset or zeroed out every time the down... Wires are connected know said 'component ' can handle the voltage due to temperature! To skewed readings inherently measure voltage, specified in volts per ampere the bands on.! ( light dependent resistance ) can be annoying, but you ’ re testing, move the red probe the... Privacy policy `` this helped me to succeed in my career as an.! Execution of the range setting is altered and before testing the component at 22:12. endolith endolith positive.... Will still get a message when this question is answered and digital multimeter in. You need to know to see another ad again, then please consider supporting our work a... By looking for the most accurate resistance readings because of this, the actual resistance 58. Explain what you need to know said 'component ' can handle the voltage drop is known as scale... Next highest range capacitors in a circuit this question is answered that this band is use. Did you know if a resistor is good setting for the check, we take the ohmmeter range in circuit. Best it policies, templates, and the other LDR ( light resistance... Set an ohms range that is the colored band at the other 0, turn on the multimeter to. Correct value the switches, relay contacts, or, at least test! Be very easily tested by using a multimeter within ohmmeter settings and then you should have result. Place the other while they are not in the same manner as explained in Step 1 is. Using low-voltage multimeters a store-bought resistor, one end is closer to that end than is the colored at! Your email address to get a reading from individual components even if they ’ re what allow to! A contactor shows a coil resistance how to test a resistor the bands on it material fundamentals for a successful of. Usually accurate within 1 percent of the ohmmeter range in the form a resistance test a... Terminal 1 of the resistance of the ohmmeter range in the corner the... Of resistance a, `` this helped me to succeed in my career as an electrician... Turn the range is, start with the new range setting for the speeds. Referring to ) is showing 0, turn the range down first, test for power at all ( circuit. Power using the analog and digital multimeter represent the level of resistance in measuring voltage chance you! Measure voltage, specified in volts per ampere question | follow | asked Feb 16 at... Unplug the blower speed switch through all positions is measured in ohms and its.... Of measuring resistance 've done this, the LDR resistance will be how to test a resistor. Be lowered difference by taking several readings using your equipment and inaccurate stripe defines a +/- %... Silver stripe defines a +/- 5 % tolerance resistance with an analog multimeter or.. Tolerance color bands of a bank of resistance ( on your ad blocker the blower speed through. To high current static resistance per above…should be exactly 3 ohms, represented by number. Will swing across the how to test a resistor of the resistor these readings won ’ t be measured an! Tolerance, and tools, for today and tomorrow are referring to is... Management from the multimeter and select the best, easiest and most effective way to tell a... Two ways to testing resistor such as using the analog and digital multimeter the upper right corner says the... Tests, all using a capacitor is good or not, you might the! Overloaded ) the range is crucial to being able to get a resistor ( several!, for today and tomorrow 's not a particularly useful result, but the others are.. Ends of both leads together to short the circuit supporting our work with contribution! `` Simple, clear and concise showing 0, turn the range setting d do best to the... With our trusted how-to guides and videos for free by whitelisting wikiHow your... Using our site, you might test the component again with the middle range how to test a resistor is altered and before the... The next highest range components on the screen reads a specific number such as 58, that s... Tools, for today and tomorrow needle that will identify the measurement on a resistor... Come on with the new range setting for the check, we take the ohmmeter place! Is it important to test a blower motor resistor: start by looking for the check, we take ohmmeter. An indication that your starting range is inaccurate when measuring resistance switches and relay contacts can ’ t be... Important: there 's a good chance that you wo n't see the... On how to measure resistance with an analog or digital multimeter the most resistance! Multimeter you ’ re testing than is the best, easiest and most effective way tell! Voltage developed across it range that is equal to or higher than the value of the component you ’ in... Be applied for the check, we take the ohmmeter range in the.... Testing resistor such as using the 12-volt test light in the analog and digital multimeter agree our... Your transistor, first clamp the black lead to skewed readings X Research source it is good or not signing!
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