Flipping P-90 Magnets

[The Golden Boy]

How would one go about flipping the magnet in a P-90?

I've got a guitar that has one old P-90 and the bridge is a new one- there's that goofy out of phase thing going on with both pickups.

 

[Zhangliqun]

Re: Flipping P-90 Magnets

P90's have two bar magnets each. It's possible that one of the magnets in each pickup is facing the wrong way. The same poles are supposed to face into the pole pieces, whether it's south facing south or north facing north. If they are north facing south, the P90 will sound extremely hollow and weak.

Flipping magnets in a P90 is easier than a humbucker because the magnets are easier to access in a P90.

 

[Aceman]

Re: Flipping P-90 Magnets

That goofy out of thing sound is cool!

 

[The Golden Boy]

Re: Flipping P-90 Magnets

So, would that be the best solution to get rid of the out of phase thing? I guess I could solder the braided ground to the hot lug of the pot and...

 

[ES350]

Re: Flipping P-90 Magnets

solder the braid to hot and you have noise galore...just flip the magnets in one of the pickups if you want them in phase...

 

[The Golden Boy]

Re: Flipping P-90 Magnets

But if the polarity is just off, so the "hot" of one is the same as the "ground" of the other...

I'll try the magnet flip if I get a chance tonight.

I'm nearly positive the old pickup is a Gibson, and I'd figure the Duncan would be matching...

 

[The Golden Boy]

Re: Flipping P-90 Magnets

Just thought I'd add this to this thread.

https://forum.seymourduncan.com/showthread.php?t=96800

I needed to flip the magnet on one of the pickups in my 1959 Les Paul Special. For giggles, I took pictures.

After removing the pickguard and the screws holding the pickup in- the cover comes off and you can remove the pickup effortlessly. Notice the metal plate at the bottom of the cavity- this is one of the kinds of mounting brackets used in Les Paul Deluxes. Along the center of the plate are 4 raised holes for screws to mount into. The inner two are for mounting P-90s and the outer holes are for mounting mini-hums.

Loosen the screws on the underside of the pickup, I didn't remove them because I didn't need to- just enough to allow the magnets to slide out. Notice one of the magnets sticking out on the right side.

The small screwdriver is touching one of the other magnets- notice that the bottom plate is loose, allowing the magnets to just slide out.'

After the magnets are flipped, I laid down a couple of pieces of mousepad foam to raise the pickup to the proper height.

Notice I let the P-90 mounting holes open.

After that I replaced the cover, then screwed in the mounting screws and put the pickguard back on.

It's a happy guitar now.

And add this quote from a poster on another forum:

You can't reverse the wiring at the control cavity end because it's single-conductor braided shield wire - if you flip it, the shield becomes hot, and so does the pickup baseplate, polepieces etc - so you get a huge amount of noise, and even worse if you touch the polepieces.

You can reverse it at the coil though - the bobbin has two thin lead wires, one of which is soldered to the center core of the shielded wire, the other to the baseplate. If you flip these you reverse the phase too.

You can do either the magnet or the coil wires, or if the guitar is in phase anyway, you can do both and make the middle position hum-cancelling. If it's out of phase, and you need to flip one, you can decide if you want the result hum-cancelling or not - if it was out-of-phase and hum-cancelling before, and you want it to stay that way, flip the magnet. If it was out-of-phase and not hum-cancelling, but you want it to be, flip the coil. (This only applies to the middle switch position BTW.)