The Multimeter is one of our most-used tools in our workshop. It’s used to test pickup continuity, phase, and resistance of our pickups, and customer’s pickups sent in for rewind or repair. Within a few seconds, we can test a pickup to determine what might be wrong with the pickup, or which direction we can go to either repair or rewind it. Let’s talk about how we use our Multimeters, and how you can use this powerful tool correctly!
There’s a lot you can do with a Multimeter, but we’re going to get to the good stuff. Here are some of the most basic of basics:
What setting Do I Use?
Multimeters are a great thing to have around the house, and your toolbox. They can help diagnose and test all sorts of things, from making sure a battery is good, to finding a short in an electrical circuit. Make sure you read the manual of your multimeter to learn what it can test. Here are some of the most popular features of multimeters:
- AC Voltage: You can use this setting to test Wall Current, not really applicable to the guitar.
- DC Voltage: Test a battery to see if it’s good or not! Very handy to have if you have a lot of guitar pedals.
- Continuity: Excellent for testing and diagnosing problems with guitar wiring – like checking to make sure everything’s grounded properly.
- Resistance (Ohms): Our most-used setting. Test a wide array of issues and get the shortcut to your problem quickly!
If Measuring Resistance: Select your Range carefully. Most of the time, you’re selecting the range of X1kOhms, or kOhm (Kilo-Ohms, or 1000 Ohms). Every meter is different, so be sure to check your manual to make sure you have the right range selected, or else you’ll get an incorrect reading, or no reading at all.
Digital Or Analog?
Either multimeter will work, but if you’re a serious bench tech, it’s a good idea to have both, as both have their strengths and weaknesses:
- Analog: Analog, or what we call a “Needle Meter” is a great way to quickly check resistance, but we use it all the time to check the phase of a pickup (More on this below). If you opt for an Analog meter, be sure to Zero your meter first. See below on how to do this:
- Digital: Digital Meters are probably the most readily available and most useful meters. There are some things that are more difficult to do with a Digital Meter, but it offers the most accurate Resistance readings out there, and they require no calibration.
Checking The Resistance:
Resistance is a term for measuring the difficulty to pass an electrical current through a wire or circuit. We use this all the time, and there’s a lot we can learn from measuring the Resistance of a guitar pickup. We use this setting to test if a guitar pickup is healthy, comparing two pickups, diagnosing problems, and testing the continuity of a circuit.
Checking the Continuity With Resistance: If you get an Ohm reading from a guitar pickup, it has continuity. You’ll get an Ohm reading, showing that the electricity is going from Point A to B, which is Hot to Ground.
Continuity is the flow of electricity through a circuit. If a circuit has Continuity, electricity can get from point A to point B. If a circuit doesn’t have Continuity, there’s a break somewhere in the signal path. We use continuity to test grounding issues, and testing whole circuits on a guitar.
There are a few ways to test Continuity. Most new digital meters have a Continuity feature, and you’ll hear an audible “beep” when the circuit closes (that setting won’t work for guitar pickups). If you don’t have a Continuity feature on your meter, you can test continuity using the Resistance setting.
See the two images below on how to determine if the connection is healthy of not:
Using the Resistance setting, you can see that the circuit is healthy when there’s no resistance. Basically, electricity is freely flowing from point A to B.
Real World Example: Let’s say you’re trying to hunt down a grounding issue in your guitar. By touching one of the terminals to a common ground (the back of the volume pot, for example), you can use the other terminal to see which other part of the guitar isn’t grounded. You should see a “0.0”, or close to “0” as possible, to see that there is a healthy connection with ground. If you see a “0.L”, you know there’s a break somewhere in the signal path and that’s the item that needs to be grounded.
Checking The Phase (Needle Meter):
Testing the phase of a pickup is a great way to see which way the pickup “Meters”, and we use this all the time when doing install work. It’s a quick way to determine if a new pickup will be in phase with your other pickups or not, but you can only do this on an Analog or Needle Meter. Here’s how you do it:
- Set your Meter to measure Resistance.
- Attach your Red Wire to the Hot of the guitar pickup
- Attach your Black Wire to the Ground of the guitar pickup (you should have an ohm reading now)
- Use a Steel Item (screwdriver / pair of pliers) to touch the magnets and observe what happens to the needle when you pull away the Steel.
The above Gif has a pickup that meters down, because when we pull the steel away from the pickup’s magnetic field, the needle is pulled towards 0 Ohms.
If you wanted to reverse the phase: You could swap the leads. Reversing the White and Black leads from the pickup will make this pickup Meter Up.
Real World Example: Let’s say you just bought a pickup with muitiple leads, like the 2-Conductor seen above. You’re about to install it in your guitar that already has a pickup installed. You can take a Phase check of both pickups to see how you wanted to wire the new pickup. If your original pickup meters up, and your new pickup meters down, you could reverse White and Black and you’ll have an in-phase guitar pickup.
Well, that’s about it for now. We use these handy multimeters all the time when diagnosing and checking our guitar pickups, and you should too! Let us know if you have any other questions!