How to Troubleshoot a Guitar Multimeter
Extraneous noise is the enemy of the electric guitar, yet taking the tiny output from a guitar pickup and filling an arena with sound is marvel of electrical engineering. When extraneous noise infiltrates your guitar's output, it is important to identify and correct it. While many of these problems can be diagnosed without equipment, in some cases, a multimeter is the only way to uncover the nature and severity of electrical issues with your guitar.
Other People Are Reading
Things You'll Need
- Digital or analog multimeter
- 1/4-inch mono phone plug with cover removed
Instructions
-
-
1
Turn on your guitar and plug the 1/4-inch plug into your guitar's jack. These tests can be done without disassembly for most passive pickup guitars. Set your multimeter to read ohms and set all guitar controls fully clockwise. Attach the black lead from your multimeter to the sleeve connection of the plug, and the red lead to the tip connection.
-
2
Cycle through each pickup, reading resistance for each. Normal resistances for single coil pickups are usually within the range of 4k to 8k, while humbucking pickups usually return values of 9k to 18k. Values close to zero indicate a short in the internal wiring. Open, or infinite resistance, readings indicate a broken wire or component. Readings well above 18k but below an open reading may indicate a component problem or a partial break in the circuit.
-
-
3
Evaluate the results from each pickup. If all read in the normal range, your fundamental wiring checks out. If one pickup produces abnormal readings, then that pickup, or its circuit, is the problem.
-
4
Test each volume pot by selecting the corresponding pickup and slowly turning the pot counterclockwise. Resistance values should climb quickly at first, then slow down. If the rate of change is steady, then the pot is a linear taper, not meant for audio use. If you are using an analog meter and the needle does not change reading smoothly, this will confirm crackling noises generated by the pot.
-
5
Return each volume pot fully clockwise and test each tone pot by selecting the corresponding pickup and slowly turning the pot counterclockwise. There should be no resistance change over the full travel of the pot. Other results indicate problems with the capacitor or the tone control wiring.
-
6
Check the continuity of the bridge ground by removing the red lead and touching it to the guitar's bridge. This should read zero or there is a problem with the ground wire between the bridge and the electronics. Return the red lead to its original position, take note of the reading then remove the black lead and touch it to the bridge. The value should be the same.
-
1
Tips & Warnings
As well as testing the guitar's internal electronics, a multimeter can be handy identifying buzzing frets by using the conductive properties of strings and fret wire.
References
Resources
- Photo Credit Polka Dot Images/Polka Dot/Getty Images
