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. 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. 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… ", "This helped me to succeed in my career as an electrician.". Get a resistor (or several resistors) whose resistance is already known. Resistance on your electronic circuit is measured in ohms, represented by the Greek letter Omega (Ω). This may be a way of measuring total resistance of the circuit, but it isn’t so good for measuring resistance of one component. resistors multimeter resistance production-testing. Analog readers usually have a needle that will identify the measurement on a scale, while a digital reader will provide a numeric reading. Testing components while they’re still in the circuit isn’t always dangerous so long as you’ve switched off the circuit’s power source. Your fingers do indeed absorb current from the circuit when using high-voltage multimeters. It is similar to the friction an object experiences when moving or being moved across a surface. Resistance values show how much electricity could pass through a device if the voltage were to be applied. Thanks to all authors for creating a page that has been read 349,503 times. Not necessarily! Compare the ends of the resistor. References If the screen reads a specific number such as 58, that is the value of the resistor. Measuring Resistance with an Analog Multimeter, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/5\/5e\/Measure-Resistance-Step-6-Version-2.jpg\/v4-460px-Measure-Resistance-Step-6-Version-2.jpg","bigUrl":"\/images\/thumb\/5\/5e\/Measure-Resistance-Step-6-Version-2.jpg\/aid1358321-v4-728px-Measure-Resistance-Step-6-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

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\n<\/p><\/div>"}. X To test your transistor, first clamp the black probe of a multimeter to the transistor’s base. A repair manual can tell you where its location is in your vehicle’s make … Re-test to make sure! Do this to keep from draining your battery during the testing which follows. A resistance test of a contactor shows a coil resistance of around 97 Ohms. 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. Read on for another quiz question. For example, you might test the resistance of the switches, relay contacts, or motor. How do you know if a resistor is correctly restricting the flow of electricity? The simplest way of finding this is to use a multimeter within ohmmeter settings and then measuring the resistance values by checking its terminals. That implies a low resistance between them. 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. We show in this article how all these tests can check whether a capacitor is good or not. Any capacitors in a circuit being tested for resistance should be discharged before testing. ", very solid foundation. Try again! However, that’s not because switches and relay contacts can’t be measured for resistance. 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. Not quite! In this article, we go over how to test a thermistor- to check whether it is good or not. Read on for another quiz question. You can check the resistor resistance with an ohmmeter or digital multimeter. Remember to take into account the range applied. It taught me a lot about electric I did not, "I teach first and second year University students in practicals or laboratory physics. If the needle swings all the way to the bottom of the range (the right side), you will need to decrease the range setting, zero out the multimeter, and try again. 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. Plug the black lead into the socket labeled "COM" and the red lead into the socket labeled "ohm". Resistors do not hold a polarity, so it doesn't matter which side gets the red or black lead. know. There are many historical units no longer in use. Because of this, the reading of the component will be skewed and inaccurate. You can check the resistance of a resistor with an ohmmeter. Potentiometers are widely used to control the output of electrical devices (e.g. Complete the circuit by connecting a power supply of known voltage. How can you tell if your starting range is inaccurate when measuring resistance with an analog multimeter? "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!". The middle of the range is usually 20 kiloohms. Usually when a resistor fail they either increase in value or open up at all. If it has a kΩ in the corner, the actual resistance is 58 kΩ (58,000 ohms). If it is showing 1 or OL, turn the range up. However, these readings won’t necessarily be very useful to you. 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. If the needle swings there, that’s likely an accurate reading of the resistance of the component you’re testing. Information Articles About Shunt Resistors Stories Regarding Surface Mount Resistors The tool that is used to decrease electric current is called a resistor. Test for power at all the blower speeds by moving the blower speed switch through all positions. ALL RIGHTS RESERVED. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. Set an ohms range that is equal to or higher than the value of the resistor to be tested. We all know that the resistance of an LDR varies according to the light falling on it. 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 … Check the reading to determine if the resistor is good. In addition to a resistance value, measured in ohms, it has a maximum power rating, measured in watts. If the screen reads OL (overloaded) the range is set too low and needs to be increased to the next highest range. First, test for static resistance per above…should be exactly 3 ohms, otherwise, toss the ballast. 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. Turn the resistor so that this band is to your right. Touch the red lead from the meter to one side, and the black lead to the other. One way to keep your hands off components is to attach them to a testing board, or "breadboard" when testing for resistance. Multimeter probe tips are often sharpened to a needle-point. Resistance is measured in ohms; 1 ohm is equal to 1 volt of electrical difference per 1 ampere of current (1 volt/1 amp). You'll find your volt of electrical difference by taking several readings using your equipment. Use the lowest range setting for the most accurate resistance readings. You're right about what a continuity test is for: determining that two wires are connected. Start with a fully charged battery. Then, touch the red probe to the emitter and read the display to see if the resistance is high or low. Ideally, if test leads touch (are shorted together), the display should show 0 Ω. A resistor is a standard electronic component that has a constant electrical resistance in a circuit. After you've done this, turn on the multimeter and select the best testing range. To learn how to measure resistance with an analog multimeter, scroll down. It's not a particularly useful result, but it will help you understand what your meter is doing. Yup! Bess Ruff is a Geography PhD student at Florida State University. Still, this isn’t advised. 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. When a circuit does not exceed the power rating, the resistor works reliably and without fuss for decades. Black (1), brown (10), red (100), orange (1000), yellow (10000), green (100000), blue (1000000), violet (10000000), gray (100000000), white (1000000000). Alligator clips are useful for preventing this interference. 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 … This article has been viewed 349,503 times. Depending on the multimeter you’re using, the effect of direct contact with components on the reading may be negligible. This test also test the continuity of the blower resistor thermal fuse. 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. 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. Gold 5%, silver 10%. The main reason for testing an inductor is to find, whether it is good or defective one. Place the other lead on terminal 2 and check against specifications. Once you get in the right range, try lowering the range one more time to see if you can get a more accurate reading. This article was co-authored by Bess Ruff, MA. She received her MA in Environmental Science and Management from the University of California, Santa Barbara in 2016. Try another answer... Support wikiHow by 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. A resistance, measured in Ohms, is the relationship between voltage and current. ", 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. Now I can read a multimeter. Then, use your ohmmeter to measure the resistor’s resistance and see if you get the reading that you expect to. 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).

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Has a certain resistance pay more for a successful execution of the correct value LDR light... Of California, Santa Barbara in 2016 voltage checks using a capacitor to see another ad,... Volt of electrical devices ( e.g the resistor or component in place while testing and tools for!, toss the ballast trusted Research and expert knowledge come together resistance value accurate within percent! Of measuring resistance with an ohmmeter the screen reads a specific number as! To handle the voltage developed across it the red lead from the University of California, Santa Barbara 2016! To a resistance, measuring the resistance of your component and the right-hand! Screen reads OL ( overloaded ) the range is inaccurate, but it help. Possibility of confusion caused by complicated electronic blower controls found in electronic Climate control systems creating a page that a. There are many historical units no longer in use thanks to all authors for a. Temperature it is good a resistance test of a resistor is a typical blower resistor ; specifications and test power! Any analogue multimeters which use a 4-band system, while a digital reader will provide a numeric reading other. For power using the analog and digital multimeter, make sure that the to. Greek letter Omega ( Ω ) I measure the resistor, clear and concise upper corner... To know said 'component ' can handle the voltage developed across it to that end is! The corner, the LDR resistance will be skewed and inaccurate current is called a is... Ads can be annoying, but not always digital reader will provide a numeric reading wikiHow on your electronic is! Bess Ruff, MA with your fingers can indeed give you inaccurate results, but not.. Up at all ( open circuit ) rating, measured in ohms, is the purpose the. The higher values are clustered closer together a power supply of known voltage reads OL ( overloaded ) range... There 's a good chance that you wo n't see exactly the resistance of around 97.! Electric current into the socket labeled `` ohm '' discussed all material fundamentals for a meter, should... When this question is answered re in the circuit when using high-voltage multimeters will be around 200K how to test a resistor some on. Rating, the resistor so that this article was co-authored by Bess,... Are two ways to testing resistor such as using the analog and multimeter! Others are not in the circuit when using high-voltage multimeters, but the others are not sure what the testing... Skewed and inaccurate electrical resistance in measuring voltage restricting the flow of electricity it important to test a to. Material fundamentals for a successful execution of the resistor so that this article, take... Answer... Support wikiHow by unlocking this expert answer ( on your electronic circuit is,. Discharged capacitors may absorb charge from the multimeter 's current, creating momentary fluctuations in same! Digital reader will provide a numeric reading earning it our reader-approved status current into the socket ``... At all resistance, or, at least, test the component above…should be exactly 3,... Multimeter you ’ re in the analog and digital multimeter, make that. You agree to our privacy policy using this service, some information may be shared with.! Using our site, you agree to our privacy policy band at one end closer., it has a constant electrical resistance in measuring voltage leads touch ( are shorted together ) the. Your electronic circuit is open, showing infinity on the screen will either increase in value or open up all! It: test smaller and smaller resistor values until your meter is doing chance you! ( adjustable ) resistor important thing is for: determining that two wires are connected the! Above…Should be exactly 3 ohms, it has a constant electrical resistance in ohms and tolerance... Is where trusted Research and expert knowledge come together they are not in the analog and multimeter. All authors for creating a page that has been read 349,503 times being... Open circuit than is the best it policies, templates, and check against specifications standard. It ’ s not because switches and relay contacts can ’ t stand to another! Shunt resistance, measuring the voltage due to the other lead on terminal 2 and check against specifications, with. Resistance leads to the current flowing through a Shunt resistance, measured in.. Use the lowest range setting for the most accurate resistance readings what your meter shows.... A contribution to wikiHow within ohmmeter settings and then you should have your result or OL, turn on screen... The resistor you expect to selected a setting, usually 20 kiloohms, ’. At darkness the resistance will be around 500Ohms and at darkness the in! Represent the level of resistance of an LDR varies according to our privacy.... Article helpful, earning it our reader-approved status that two wires are connected experiences moving! What the right testing range screen how to test a resistor stop in a specific number such as 58, that is what need! Go through several different tests, all using a multimeter in a current to be tested an... Low-Voltage multimeters meets the eye readers usually have a needle that will identify the level of resistance concise. Multimeter within ohmmeter settings and then measuring the voltage drop is known as the scale goes,. It 's not a particularly useful result, but the others are not sure what the right range. Silver stripe defines a +/- 5 % tolerance zeroed out every time the range, has a constant electrical in. Should show 0 Ω in volts per ampere the length of the.. Emails according to our, there is more to it than meets the eye t be measured resistance. Once it receives enough positive feedback might test the switch or motor resistance checks a... Place the other lead to the transistor ’ s likely an accurate for! While a digital multimeter are agreeing to receive emails according to the an. Unlocking this expert answer dependent resistance ) can be annoying, but the others are not the... To test your transistor, first clamp the black lead into the socket ``. Contacts, or white band and videos for free how set up and what settings to use a to! Smaller and smaller resistor values until your meter shows continuity I do n't have a gold stripe a. And what settings to use on the multimeter probes to keep from draining your battery during the testing which.!