Magnet Madness

barnsleyboy

Afternoon all, Hope you are well.

I'm doing a bit of work on my nieces's Pacifica and noticed a big difference in volume between the single coils and the bridge humbucker. Inside the cavity I can see why - the magnets aren't where they should be!

I've put them where they are supposed to be but they seem to be pretty weak i.e. the attraction between the bar magnet and the pickup pole pieces isn't very strong. I'm thinking part of this is that the pole pieces could do with a good clean to get rid of the rust and corrosion so that there is better contact between the faces.

But I'm also thinking that maybe over time they have demagnatised and could do with replacing. I have a couple of spare ceramic magnets which I thought would be an ideal replacement. However, swapping them over, I'm faced with the problem, below:

Remembering back to my Physics lessons, I'm assuming that the pole pieces at the ends of the pickups (the high and low E's) are of opposite polarity to the bar magnet, hence the bar won't sit in the correct orientation. If I rotate them by 90 degrees, bingo, they stick perfectly.

Unfortunately the cavity isn't deep enough for me to leave them like this. I don't want to replace the pickups So the alternatives are,

- Cut out channels in the guitar body to accommodate the extra magnet depth - Don't really want to do this

- Cut the magnets in half lengthways with a hacksaw - possible, but will me sawing them in half with a hacksaw weaken the magnetic field?

- Lay them flat in the 3rd photo above but super glue them into position so they are not skewed - maybe,

- Glue the old magnets back and leave well alone

Any ideas?

Funkfingers

barnsleyboy said:

The brownish rectangles on the undersides of the two single coils pickups are the remnants of the adhesive (or double-sided tape) that originally held them in position. By all means, clean it away. You may find that the steel studs beneath are lovely and shiny.

If you are going to replace the magnets, the main consideration is orientation. The centre pickup is intended to operate as reverse wind / reverse polarity to the other two. (NOTE: The white "hot" output conductor on the centre pickup is soldered on the low E side whereas, on the neck pickup, it is on the high E side.) Thus, the two replacement magnets should be attached in opposite polarity to each other.

I would use glue.

barnsleyboy said:
Cut the magnets in half lengthways with a hacksaw - possible but will me sawing them in half with a hacksaw weaken the magnetic field?

If you don't want them to shatter like old-fashioned toffee, use a Dremel.

barnsleyboy

Funkfingers said:

If you don't want them to shatter like old-fashioned toffee, use a Dremel.

Hmm, I'm thinking maybe put the old magnets back in! No such luck with the bright shiny pole pieces, they're rusty. I've cleaned them up the best I can. Good point about the orientation.

barnsleyboy

Old magnets super glued in, reversed the polarity so spun the neck pickup magnet round by 180 degrees, everything assembled and works except in position 2 (neck and middle), massive volume drop - sounds like they are out of phase and cancelling each other out. I'm wondering if the magnets shouldn't have been opposite polarity. I suppose I could open her up again and just rotate the centre pickup by 180 degrees to sort it. Quickest way might be to leave the strings on and take the bridge off to remove the pickguard. ..... Blast!

Funkfingers

If selector switch positions 2 and 4 both sound weak, rotate the magnet on the middle pickup.

If only the neck/middle selection sounds thin and weak, rotate the magnet on the neck pickup.

barnsleyboy

Problem is only in position 2, so sounds like the neck is the culprit!

Funkfingers

barnsleyboy said:

I could open her up again and just rotate the centre pickup by 180 degrees to sort it. 

Rotating the single coil pickups would change nothing. 

SteveRobinson

To reverse the polarity of the pickup, flip the magnet over. N-S is top to bottom, as you want all poles to have the same magnetic orientation of course

barnsleyboy

All sorted, thanks @Funkfingers & @SteveRobinson for your assistance!