pickups wiring question

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842
I have a guitar that I need to reverse the phase of the pickups in (to hopefully solve a piezo problem). The pickups are both two conductor Duncans - a Seth Lover and Antiquity. Does this mean that when I crack the guitar open, I'll have only two wires leaving each pickup - one to ground and one to the 3-way (hot wire)? And to reverse phase all I need to do is swap the wires for each pickup?

Thanks for any advice you can give!
 

John Phillips

Member
Messages
13,040
You can't reverse the phase on those.

Well, you can, but you'll need to get inside the pickups to do it. Which means taking the cover off.

The problem is that one of the two conductors is not only the ground for the coil, but also the shield. If you reverse the connections, the shield will become the hot, so you'll get an almighty hum if you touch the pickup cover (and a fairly noticeable one at all times).

If you do want to take the pickup apart, reversing the phase is fairly easy - just flip the magnet. Getting the cover off and back on an unpotted pickup is relatively easy. I'll post how to do it if you want.
 

Jim Collins

Member
Messages
1,939
It isn't that easy, with these pickups. These two pickups have a single conductor inside a braided shield. The braided shield serves two purposes. It is the ground lead for the coils, but it is also the ground for the metal base. The metal base of the pickup -- and the cover, if the pickup is covered -- must be grounded. If you were to simply swap the connections of the braided shield and the single conductor, the base -- and cover, if it exists -- are suddenly in the circuit. The result is all kinds of noise.

To reverse the phase of these pickups, you must perform surgery on the pickups. You are either going to have to flip the magnet in each pickup, or you will have to provide an independent ground for the metal base. In either case, you'll have to take the pickup apart, which will mean removing the cover.

Pickups with three or four conductors plus ground allow you to simply reverse the hot and ground leads of the coils while leaving the base and cover grounded.
 
Messages
842
Thanks for the info. John, if its fairly easy for a newbie to guitar tech stuff and I can't kill myself or break the guitar, please post it and I'll try it this weekend.

Thanks in advance!
 

John Phillips

Member
Messages
13,040
Take the pickups right out of the guitar. Lay them face down on a soft but firm surface (a towel on a workbench is ideal).

Get a strong but sharp knife with a curved blade - the large blade on a Swiss Army knife is good. Holding the pickup firmly, cut down through the solder blobs at each side - if you rock the blade along its length, it will cut, with reasonable force. Take care not to break through suddenly or you might damage the coil.

The cover should now come off fairly easily. Undo the four small screws underneath. Pry the baseplate away from the coils slightly, and push the magnet out lengthways. Turn it 180¼ along its axis, so the opposite long edges are under each coil. Slide it back in and replace the four screws.

Put the cover back on - making sure it's fully down around the screw polepieces - and resolder it. You'll need a very powerful iron or gun for this - possibly an old-fashioned gas-ring type.


If that sounds too scary, get a pro to do it. There is a small chance of damaging the pickup coils or wiring if you aren't careful... although it's not that likely.
 




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