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Tim Stanley's FAQ regarding determining the phase relationship of a pickup coil.
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Here is a method fellow alt.guitar contributor J. D. Kimple told me
about to resolve phase problems with pickups.  It works using a
regular old VOM on passive guitar wirings.  With this test, you do not
have to de-string your guitar to test questionable wiring.  And you
can simply avoid trial-and-error wiring of a new pickup.

I tried to write this FAQ assuming that non-electrical engineers would
read it.  However, I assume you have some technical sense and ability.
I recommend reading Ralph Denyer's Guitar Handbook for a good
fundamental lesson on pickups (single/humbucker, coil taps, phasing).
It is a great book about guitars in general.  Every section is worth
reading and the book is worth owning.

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Equipment
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1.  Beg/Borrow/Steal a volt-ohm meter - the kind with the needle (got
to have the needle, none of this digital display stuff).

2.  Set it to the 10K ohm setting (sometimes you may need to use the
1K ohm setting, too).

3.  Clean the resin off the alligator clips you keep in the storage
compartment in your guitar case, and clip the red meter probe to the
one alligator clip and the black to the other alligator clip.  Be sure
the probes make good connection and that resin doesn't get in the way.
It really doesn't matter which probe goes where - just stick with some
convention - this is important to establish phase.

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Single coil
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4a.  If you are working with a single coil, you have one coil (duh)
which has two real wires, and maybe a ground/shield wire too.  Life is
easy.  Ignore the ground/shield wire for now.

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Humbucker
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4b.  If you are working with a humbucker, you have two coils, and up
to 4 wires, plus maybe an additional ground/shield wire.  Ignore the
ground/shield wire for now.  

If you have two wires, you can assume that the humbucker can only be
wired as a standard series humbucker, and you can treat it as a single
coil for this process.  In fact, what you have is one wire to each
coil, and they are internally connected.  Don't worry about this
detail.

If you have 4 wires, you need to determine which wires belong to which
of the two coils.  First, I refer you to the Stewart MacDonald
humbucker wiring FAQ for wiring color codes of various manufacturers.

However, to determine/verify which wires belong to which coil, choose
one wire and attach one meter probe to it.  One by one, attach the
other meter probe to each of the other three wires.  One and only one
of the three connections should show continuity.  Two of the three
connections should indicate no continuity.  If this is not the case,
you have a broken pickup - some wires inside are broken or shorted.
If more than one wire shows continuity, you have an internal pickup
short.  If no wires show continuity, you have broken internal
connection.

Assuming that the pickup is in working order, you have now identified
the pair of wires that belong to one of the coils.  Check to make sure
that the other two wires show also show continuity as they should be
attached to the other coil.  Now you have the wires sorted out for the
two coils.

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Unconnected pickups
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5a.  If you are working with unconnected pickups prior to installation
in the guitar - all the better.  Connect the two meter probes to each
of the two wires associated with one coil.

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Connected pickups
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5b.  If you are working with pickups that are wired into your guitar
already, that's OK.  Plug a cord into the guitar.  Turn all volumes up
to the max.  Open your tone controls up to the most trebly position.
Put the pickup selector switch to select the one and only one pickup
you are working on.  No combo pickup positions.  If you have coil taps
- turn them off for now.  If you have phase switches, put them in what
you believe is their in-phase positions.  Connect the red meter probe
to the tip of the guitar chord plug, and the black meter probe to the
shaft of the guitar chord plug.  You have now hooked the meter right
into one pickup.  (remember - this won't work with active electronics).

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Sanity check
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6.  You should see that the meter reads somewhere between 5K ohm (for
older single coil pickups) to 18K ohm (for the most nasty high-output
humbucker pickups).  That is good.  If this is not true, recheck your
steps, adjust the meter settings, etc.  Don't get an ego complex over
the exact DC impedance of your pickups - that is not the point here.
But, for the record, everyone knows that macho guitars have pickups
with *at least* 10K ohm DC impedance ;-).

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Establishing coil phase
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7.  Using a magnetic tool (screwdriver, needlenose pliers), gently tap
a pole piece of the coil/pickup.  Note that the meter needle will move

	very slightly* either to the left or to the right when you tap the


pole piece, and then drop back to its original position.  Repeat until
you are absolutely sure of the exact direction of movement that the
actual tap causes and make a note of the direction.  

If you get no meter movement:
	a) try another setting of the ohm-meter (1K or 10K)
	b) be sure you have good meter connections
	c) tap the pole piece a little harder
	d) if the pickup is in the guitar, make sure volume is maxed
	e) if the pickup is in the guitar, make it is the only selected pickup

If you have a humbucker with 4 wires, you can use this procedure to
identify which coil is attached to which pair of wires so that you can
position the humbucker appropriately if you are using more complex
switching schemes where you care about the orientation of each coil.
Obviously, if the magnetic tap doesn't cause any meter movement, the
meter is attached to the wrong coil wires (so tap the other coil pole
pieces), or something is broken.

Notice that if you reverse the connections of the meter, the direction
of meter movement is reversed.  As such, let's establish a convention.
Find the connection orientation that results in a clockwise meter
movement.  Let's call the coil wire attached to the red meter probe +,
and let's call the other coil wire -.  This is just a convention, like
all +/- electrical conventions.

If your alligator clips had a lot of resin on them, at this time,
perhaps you should write down which color wire was attached to the red
probe, and which color wire was attached to the black probe.  We are
going to repeat this for all of your coils and you are going to have
to remember it.

8.  Establish the coil phase convention for all of the pickup coils.

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4-conductor Humbucker
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9.  If you do not have a 4 conductor humbucker, skip this.

Again, refer to the Stewart-MacDonald's wiring color code FAQ as the
ultimate reference.  However, if you have some odd pickup, create your
standard humbucker wiring configuration as shown below:

If this is one of the coils with the + and - convention shown:

+  --OOOO--  -

then connect the - of the two coils in series.  

+  --OOOO---OOOO-- +

You now have a standard humbucker with the two + wires unconnected
waiting be be wired into your guitar.

If I am wrong about this folks (and there is a very real chance that I
am), please inform me!  One test, obviously, is to listen to this
pickup alone, not in combination with other pickups.  If it is thin
and weak sounding, then I am wrong!  Instead, you should connect the -
of one coil to the + of the other coil.  One of those two
possibilities will result in the full-bodied humbucker sound.

Now, using the two unconnected wires of the standard humbucker,
re-establish its phase convention.  We need a + and a - so we know how
to connect this with other pickups, and I am leaving room for the
possibility that I am mistaken about the proper method to connect two
coils into a humbucker.

This sort of trial and error is often necessary with unknown pickups,
and I regret any confusion I might cause until I get some feedback.

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Bringing all pickups together
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10.  Once the phase convention of all pickups is established, we get
in-phase pickup coil combinations by connecting the +s together, and
all -s together in parallel (the typical way of connecting multiple
pickups):

+ --OOOO-- -	Pickup 1
  |      |
  |      |
+ --OOOO-- -	Pickup 2

A parallel out-of-phase pickup coil combination is made by connecting
a + with a -.

- --OOOO-- +	Pickup 1
  |      |
  |      |
+ --OOOO-- -	Pickup 2


A parallel out of phase connection sounds very thin and weak.  Robert
Cray-ish and then much less.  At high amp volume, it might be good in
some applications.  At low volume, it sucks.

There is no notion of a coil being in phase with itself - phase is
always with respect to another coil.  A pickup can not be out of phase
with respect to itself.

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Summary
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11.  If you find that all pickup taps cause needle movement in the
same direction when you connect/select each pickup separately, then
your wiring is properly phased when you connect multiple coils/pickups
in parallel.  When a pair of pickups having opposite needle movement
are connected, they are out-of-phase.

Regards,

T

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Digest of pickup phase articles
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From: tjs@eecs.umich.edu (tim stanley)
Newsgroups: rec.music.makers.guitar
Subject: Re: Strat Pickup Wiring Question
Date: 19 Jul 94 13:19:43
Organization: U of M

In article <30gnh7$5jr@sasuga.hi.com> rogers@sasuga.hi.com (Andrew Rogers) writes:

   >How do you tell if a pickup is reverse wound?  I imagine that if it is reverse
   >polarity, it will attract another ordinary pickup magnet face-to-face, right.

   Yes, it will.  If that's not practical - e.g., due to the pickups already
   being mounted in a guitar - you can tell with a compass.  (I use a hiker's
   compass that I picked up at a yard sale, although a dimestore compass is OK.)

Hey - clever idea.  Gotta remember this...

   I can believe that - as far as I know, neither the Vintage nor Squiers use
   an RWRP middle pickup.  In the former case, that's for reasons of
   authenticity; in the latter case, cost.

Actually, my Korean Squier *did* definitely have RWRP in the middle
position.  Audibly so - since, after all, this is a Strat and you can
hear this sort of noise.  Just one data point for you though, and I am
not sure about the year of its manufacture (1988/9?).

   >I don't notice any more hum in the 1/2 and 2/3 positions for th 5-way either.

   No, but with the RWRP you'd notice a lot less.

Exactly!
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