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PostPosted: Wed Apr 22, 2009 7:28 am 
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Cocobolo
Cocobolo

Joined: Thu Dec 07, 2006 11:37 pm
Posts: 499
Location: United States
Hello All,

I got little project I’m doing for a friend. Actually, it’s been in my shop for some time now.
I’m finally getting around to it. It’s a ps-37 Jackson electric guitar. I’ve got all the new parts
together, and ready to start. That’s when I noticed a little discrepancy. It may be nothing to be
concerned about, but, I thought I would run it by you guys, and see what you think about it.

The pickups are not a matched set, at least I don’t think they are. (Pic below) One is a dual coil
standard, and the other is a dual coil split. It appears that somewhere along the line, the original
pickup was replaced. I say that because, one says Jackson right on it. I got a wiring diagram at the
Seymour Duncan website (Link below). It was the closest thing I could find for what I have.

So, the question is - Can I assume that the Jackson pickups’ red is hot, white is neutral, and bare
is ground. Tap the red and white on the other pickup, and carry on?


http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=2h_2v_1t_3w

Attachment:
Kent Pickups OLF.jpg



Robert


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PostPosted: Wed Apr 22, 2009 7:40 am 
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Brazilian Rosewood
Brazilian Rosewood

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You can't make any assumptions on color codes between various manufacturers, various years, or even various days (I've certainly run across a few with the colors mixed up from the factory).

Ask the meter. If you're not familiar with testing phase on multi-meters, and if nothing comes up on an archive search, let us know and we'll go in to more details then.

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PostPosted: Thu Apr 23, 2009 4:44 am 
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Cocobolo
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Hi David,

I have a multi-meter that tests a/c, d/c, and ohms. Is this type of meter you’re talking about?

Robert

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PostPosted: Thu Apr 23, 2009 8:58 am 
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Brazilian Rosewood
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Yes. To test phase, you need to see whether a coil has a positive or negative charge induced as metal moves toward it, or away from it. You can use the DC voltage setting on the meter (usually the lowest setting, typically 200mv), or by the watching the change in the resistance reading. You're not really changing the resistance to the degree that the meter tells you as you move the field, but the voltage generated will change the reading none the less, and typically show a more substantial change than the voltage reading.

So set your meter on the appropriate resistance (i.e., 20kΩ), hook the red lead from the meter to the red wire of the Duncan pickup, and the black (ground) lead to the green wire. You should get 4-8kΩ reading on the meter. Slowly move a screwdriver, scale, any iron tool down toward the adjustable screw bobbin (analog meters you can move quickly here, digital meters you'll have to move slower with slower sampling rates). If the Duncan pickup is made as normal, you should see the resistance reading rise when you move toward it, then fall as you move away. This is normal, standard phase, though there are certainly some makers that set theirs up in reverse. If you get the reading I mentioned, you have just confirmed that the green is the ground lead of that coil, and the red is hot.

Move to the black and white wires. Just for sake of learning and demonstration, hook the red lead of the meter to white, and the black lead to black. Now on a normal Duncan pickup, you would likely see the resistance reading fall as you move a tool toward the solid slug coil, and rise as you pull away. This would tell you that you have the coil hooked to the meter in reverse phase from the other one. So that means the black lead should be hot, and the white to ground. To confirm you can hook the white pickup lead to the black (ground) meter lead, and the black pickup lead to the red (hot) meter lead. Now you should see the resistance reading rise as you move toward the coil.

So jot these notes down as you test, and you have green ground and red hot for one coil, and white ground / black hot for the other. Hook a ground and a hot together (like white and red), then you are left with a series wired humbucker with green as final ground and black as hot.

So to check your Jackson pickup, it's reasonable to assume the bare is ground and white and red are opposite leads in a series wired pickup, though not guaranteed. One side of one coil could also be dedicated to the bare ground, the white or red be the end of the opposite coil, and the remaining wire a coil split, connected to the junction between the two. I'd guess that as unlikely, but you can check easily enough by testing the resistance between the three leads. For example, if the resistance were say, 10kΩ between the red and white, no conductivity between bare ground and either of the others, and direct conductivity between the ground wire and the base plate, then the ground is just a ground and not dedicated to either coil. This is probably the case, and to avoid typing another chapter I'll leave it there. If not, we can go through other options then.

Then hook the red wire to the red meter lead, and the white wire to the black lead. If the reading goes up when you move metal toward the pickup, then red should go to hot and white to ground to match the phase of the Duncan. If it goes down when you move toward, that's telling you you have it hooked to the meter in reverse, and red should ultimately be ground and white to hot.

It's really simple, and I don't even keep track of color codes anymore because it takes me less time to hook each pickup to the meter than it does to pull the presumptive charts off the shelf. It's a 15-30 second test for a pair of humbuckers, and if you plan to do work on electronics often is worth understanding.

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PostPosted: Fri Apr 24, 2009 7:35 am 
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Cocobolo
Cocobolo

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Hi David,

Thanks for the information! I’ll try it, hopefully this weekend, and post the results.

Thanks again, Robert

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PostPosted: Sun May 17, 2009 10:01 am 
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Cocobolo
Cocobolo

Joined: Thu Dec 07, 2006 11:37 pm
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Well, I finally got around to testing the pickups with the meter. Either I’ve done it wrong, or the
meter is not the correct one to use, or the pickups are shot!

I followed your directions David, however I can’t get a reading. The only way I could get a
reading was to attach one meter lead to the bare wire, and one to the metal base plate of the
pickup.

Here’s a few pics to show what I’ve done. The only way I could get a reading was to attach one
meter lead to the bare wire, and one to the metal base plate of the pickup.

Any suggestions?


Attachment:
Meter Test 1 OLF.jpg



Attachment:
Meter Test 2 OLF.jpg



Attachment:
Meter Test 3 OLF.jpg


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PostPosted: Sat May 23, 2009 8:58 am 
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Koa
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Any luck yet? If you are not seeing what you want or expect from the meter, you could just try hotwiring the pickups to a 1/4" cable and plug them into an amp to see what is going on. Tap on the poles with a screwdriver to see which coils are working, and you can even make a quickie bow and arrow type "instrument" with one guitar string, this way you can hear the pickups without wiring them up inside an instrument and get the phase correct.

Also, David, your description of pickup testing is really great, it should go in the tutorials or something!

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PostPosted: Sun May 24, 2009 10:37 am 
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Koa
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Just in case it helps, here is a meter in use.

One of the coils
Attachment:
IMG_3180.JPG

The meter is set to 20k, and reads 6.91 ohms.

Bare wire to the metal base plate
Attachment:
IMG_3179.JPG

Meter at the 200 ohm setting, reads 1.1 ohms, there should not be much resistance at all here. I can't tell from your picture, if you have a high reading here, and can't get a reading anywhere else, something may be fishy with your pickup, that's why i suggested hotwiring the different combinations of coils, if you get no sound you know something is wrong.


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PostPosted: Sun May 24, 2009 11:03 am 
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Koa
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jordan aceto wrote:
The meter is set to 20k, and reads 6.91 ohms.


Oops, should say that the meter reads 6.91, but the measurement in ohms is 6.91k ohms, duh.

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