Why Does Switching the Leads on a Multimeter Give Different Continuity Readings

Introduction

• A continuity exam tells the states whether two things are electrically continued: if something is continuous , an electrical current can flow freely from i stop to the other.

• If there's no continuity, it ways there is a break somewhere in the circuit. This could indicate anything from a blown fuse or bad solder joint to an incorrectly wired excursion.

• Continuity is one of the well-nigh useful tests for electronics repair.







• To begin, make sure no current is running through the excursion or component you want to exam. Switch it off, unplug information technology from the wall, and remove whatever batteries.

• Plug the black probe into the COM port on your multimeter.

• Plug the crimson probe into the VΩmA port.

• Switch on your multimeter, and set up the dial to continuity mode (indicated by an icon that looks like a sound wave).

• Non all multimeters have a defended continuity style. If yours doesn't, that's okay! Skip to Stride six for an alternating way to perform a continuity test.

• The multimeter tests continuity by sending a lilliputian current through ane probe, and checking whether the other probe receives information technology.

• If the probes are connected—either past a continuous circuit, or by touching each other directly—the test current flows through. The screen displays a value of aught (or nigh zero), and the multimeter beeps. Continuity!

• If the test current isn't detected, it means there's no continuity. The screen volition display 1 or OL (open loop).

• To consummate your continuity examination, place one probe at each end of the excursion or component you want to examination.

• As before, if your circuit is continuous, the screen displays a value of zero (or well-nigh nada), and the multimeter beeps.

• If the screen displays ane or OL (open loop), there's no continuity—that is, there'south no path for electric current to period from one probe to the other.

• Continuity is non-directional, meaning it doesn't thing which probe goes where. But there are exceptions—for example, if there's a diode in your circuit. A diode is like a one-mode valve for electricity, meaning it volition show continuity in one direction, only not in the other.

• If your multimeter doesn't accept a dedicated continuity examination fashion, you tin can still perform a continuity test.

• Turn the dial to the lowest setting in the resistance way.

• Resistance is measured in ohms, indicated past the symbol Ω.

• In this mode, the multimeter sends a petty current through ane probe, and measures what (if anything) is received by the other probe.

• If the probes are connected—either by a continuous circuit, or by touching each other directly—the exam current flows through. The screen displays a value of zero (or near zero—in this case, 0.8). Very low resistance is some other way of saying that nosotros have continuity.

• If no electric current is detected, it ways there'south no continuity. The screen will display 1 or OL (open loop).

• To complete your continuity test, place one probe at each finish of the circuit or component you want to exam.

• It doesn't matter which probe goes where; continuity is not-directional.

• Equally earlier, if your excursion is continuous, the screen displays a value of zippo (or nearly zero).

• If the screen displays i or OL (open up loop), there's no continuity—that is, there'south no path for electric current to flow from i probe to the other.

• Plug the black probe into the COM port on your multimeter.

• Plug the red probe into the VΩmA port.

• Switch on your multimeter, and set up the punch to DC voltage mode (indicated by a V with a straight line, or the symbol ⎓).

• Virtually all consumer electronic devices run on DC voltage. AC voltage—the kind that runs through the lines to your business firm—is considerably more dangerous, and beyond the telescopic of this guide.

• Most multimeters are non autoranging, meaning you will need to prepare the correct range for the voltage you expect to measure.

• Each setting on the dial lists the maximum voltage it can mensurate. So for case, if you lot expect to mensurate more than 2 volts but less than twenty, apply the 20 volt setting.

• If yous're not sure, start with the highest setting.

• Identify the red probe on the positive terminal, and the blackness probe on the negative terminal.

• If your range was set besides high, you may not go a very authentic reading. Here the multimeter reads 9 volts. That'due south fine, just we tin turn the dial to a lower range to get a better reading.

• If y'all fix the range too depression, the multimeter simply reads i or OL, indicating that it is overloaded or out of range. This won't hurt the multimeter, simply we need to set the dial to a higher range.

• With the range set correctly, nosotros become a reading of 9.42 volts.

• Reversing the probes won't exercise any harm; it just gives u.s.a. a negative reading.

• To brainstorm, brand sure no current is running through the circuit or component you want to test. Switch it off, unplug it from the wall, and remove any batteries.

• Remember that y'all'll be testing the resistance of the unabridged circuit. If you lot want to test an private component such as a resistor, test information technology past itself—not with it soldered in place!

• Plug the blackness probe into the COM port on your multimeter.

• Plug the red probe into the VΩmA port.

• Switch on your multimeter, and set the dial to resistance way.

• Resistance is measured in ohms, indicated by the Ω symbol.

• Most multimeters are not autoranging, meaning you will demand to set up the correct range for the resistance you lot wait to measure. If y'all're not certain, commencement with the highest setting.

• Identify one probe at each stop of the circuit or component you want to test.

• It doesn't thing which probe goes where; resistance is not-directional.

• If your multimeter reads close to zero, the range is set too high for a practiced measurement. Plough the punch to a lower setting.

• If you ready the range as well low, the multimeter simply reads ane or OL, indicating that it is overloaded or out of range. This won't hurt the multimeter, only we demand to set the dial to a higher range.

• The other possibility is that the circuit or component you lot are testing doesn't have continuity—that is, information technology has infinite resistance. A non continuous excursion will ever read 1 or OL on a resistance test.

• With the multimeter fix to a usable range, we get a reading of 1.04k ohms.

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Source: https://www.ifixit.com/Guide/How+To+Use+A+Multimeter/25632

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