Testing pickups in guirar w/o strings

[Sooner Boomer]

A friend had me try to troubleshoot a guitar over the phone for him. I *think* it may have a bad pickup, but he has no way to test it. I was thinking of making (for lack of a better term) a "pickup stimulator". I think I could get by with something quite simple - a 555 driving a small coil. The coil would be placed directly over the pickup(s). A signal coming out the output jack would indicate that the pickup is working (for a certain value of "working"). Any thoughts on this?

[Justin Thomas]

How much of a test do we need? If it has 2 or more similar pickups, just use the selector switch and a screwdriver to cycle through the positions. Tap a pole piece on the suspected pickup. If no sound or much weaker, bam, done.

Justin

[rjb]

How much of a test do we need? If it has 2 or more similar pickups, just use the selector switch and a screwdriver to cycle through the positions. Tap a pole piece on the suspected pickup. If no sound or much weaker, bam, done.

Except for the "bam", I was about to say pretty much the same thing. Try not to hit it that hard.

-rb

[Sooner Boomer]

Thanks for the replies. I'd like to do a *bit* more than just a bam! test. After a bit of contemplation, I think I'll dig through the parts box and see how close I can get. What I have in mind is a 555 in astable mode driving just the coil from a dollar store set of headphones. Parts values on caps and resistors to give something like a 1KHz - 8KHz (-ish) range. I don't know if the pickup coils can pick up the EMF generated by the coil laying right on top of them (driven by 9v battery). Cost for the project should be small.

The advantage of this is that it tests more functions than just the tapping test - I can easily test pickup function, switch function, tone circuits, and volume control. If the output is dead, one will still have to dig into the guitar, but with a strat, everything comes out with the pick guard. Once it's pulled, it's hard to test pickups (except for tap test). With something stimulating the pickups, I could go through the circuit with either a voltmeter or a signal tracer (small amp/speaker).

I'm also recommending my friend buy a small amp-on-a-plug to field test guitars before he buys them. Something like a JOYO JA-03 or similar.

[ZRGuitarPickups]

Hey Sooner Boomer,

It sounds like you're trying to build another inductor to 'induce' sound into your pickup. If so, here's a great resource for building a test coil, and sending the signal to a computer for analysis. This guy is using a circuit built by Ken Willmott - I'll give you a like to his site too..

http://www.tdpri.com/threads/a-doubl...nly-25.666998/

Read to the very end of that post, and he lists all of the equipment he used to test the pickup outside of a guitar. Some useful stuff!

Here's a link to Ken's site - search through for "Electric Guitar Pickup Measurements" - That gives detailed instructions to build this stuff.

Hope this helps!

- Zach
ZRGuitarPickups

[glebert]

I got a project bass that didn't have strings, bridge, or tuners and wanted to make sure the electronics worked before I dropped money on parts. I held the project bass face-to-face with another bass such that they were "sharing" the strings and was able to verify basic functionality that way. Not as interesting as what you are considering, but it worked.

[J M Fahey]

I´ve used a tuning fork held 1 inch away since forever.
Way more useful than a plain "thunk", allows me to check relative pickup output, etc.
A very useful tool to be carried in the toolbox and ... it also doubles as a Tuner