How to Test a Speaker Wire With a Voltmeter
If you are experiencing problems with your audio system or stereo speakers, you can use an analog voltmeter to test the wiring continuity. Sometimes, speakers wires can become frayed or cut when moving them around, and this will cause the speakers to short or produce no sound at all. However, these breaks can hard to spot with the naked eye, so you will need another way to confirm whether the wiring is damaged. This simple step-by-step guide will show you everything you need to know.
Step 1 - Turn Off all Audio Components
First, you should turn off all the components in your stereo system. This will help ensure that you don't create a short or otherwise damage the equipment while you're working on the system.
Step 2 - Disconnect Wires From Speaker Box
Remove the positive and negative speaker wires from the speaker box. You may be able to remove them by pressing two clips, or you may have to twist the two connectors counterclockwise instead.
Step 3 - Disconnect Wires From Stereo
Next, disconnect the wires from the rear of the stereo amplifier or receiver. Be careful to fully disengage the wiring lock mechanism before attempting to remove them. Like the speaker boxes, you may have to press down a clip or twist the wire lock cap for this part.
Step 4 - Connect One End of the Wires Together
After you remove the wiring from the speakers and the stereo unit, twist together the two individual cables at one end. This will create a closed circuit that you can use to test for continuity. You don't need to secure them tightly; in fact, twisting the wire ends too tightly may make them hard to separate later, and may even cause damage.
Step 5 - Set Your Voltmeter
Switch the voltmeter on and turn the selector dial to the Ohms position. This is the setting that is used to test resistance in the speaker wire.
Step 6 - Calibrate Voltmeter
Before you can test, you should ensure that the voltmeter will display an accurate reading by touching the black and red probe leads together. A reading of 0 Ohms, no resistance, indicates that the voltmeter is working properly. Any other reading indicates a problem with the unit's accuracy, so you will need to switch it out for a new one.
Step 7 - Test the Speaker Wire
Touch the two probe leads to the bare speaker wires on the open end of the circuit (the two wires that are not twisted together). If the voltmeter displays infinite resistance, then the cable has a cut or break somewhere along its length, and it will need to be replaced. A continuous cable, on the other hand, should display a small amount of resistance if it's undamaged.