Measuring the values of pickups IN a guitar is actually an extremely useful technique.
The only values that I would attempt this on are basic DCR measurements, you can do inductance and capacitance but you’ll get other affects that may get confusing unless you fully understand a circuit.
Considerations:
- A great way to test the wiring of a guitar -vs.- what’s expected.
- The volume pot needs to be on MAX VOLUME
- Passive Circuits only.
- Special design RC circuits can interfere with the readings but this is rarely done.
- High Value Volume Pot (say 500K) gives you a closer to real reading (less loading)
- The reading will be very roughly 6% less than the unloaded (not hooked up) reading of the pot, higher end DCR pots have larger variation.
The most important aspect is that the volume must be on full. The reading in the most simple arrangement (let’s say a bridge and volume pot) will yield a value that is roughly 6% or so less than the unloaded value:
To Isolate a pickup
- You can measure the pickup directly or on the output of the guitar with the pickguard on.
- Set the 5 position switch to select ONLY the pickup being measured.
- Make sure any “switching” circuit other than a stock 5 way are turned OFF
Why should the pot be full on?
You are measuring a parallel resistance circuit –
- Example: 250K // 6.5K yields approx. 6.3K
- Example2: 250K// 12 K yields approx. 11.4K
– In general, the higher the resistance of the pickup, the greater the error.
This is a fantastic easy way to verify more complicated circuit functionality as well. For example a series arrangement of pickups you can just add the “measured” values and if you end up with roughly double value, then you know the wiring is correct.