2 Humbuckers, 1 Volume, 1 Tone/push pull coil split - Help Please!

[rabidgerry]

Hi guys, I need help with this wiring.  I have wired this mod in one of my guitars because it had the mod done to it when I first bought it and I've always thought it was neat and descrete.

However when I changed pickups many moons ago and wired up the new bridge pup things have never been quite right.

So the functionality was working yes, but to me the signal has always seemed quite strangled or something.

Also the push pull I thought had got damaged from something careless done by me.

So I swapped it out last night and wired up following this diagram (see attached) and it all works ok but again sounds strangled on full humbucker and also I get mega noise when I touch the dam control knob.  The noise to me sounds as though I am touching the signal end of a guitar cable.

I am not sure but I believe this has something to do with the neck pickup which only has a signal wire and earth and a shield.  However this pickup can be split, because when I first bought this guitar it had two pickups in there with only three wires and they were both wired to the push pull and both split with out any issues.  So something must have been different but I cannot for the life of me figure it out.  Can someone please help?

***************Important****************
I might need to point out that the three wire pickup works like this, the white wire is a join between positive and negative.  I have tested this and know it to be true.  If I connect multimeter to the shield and to this white wire and leave out the red wire entirely I get half the humbucker resistance (about 4k).  If I connect multimeter to the red wire and the shield wire I also get 4k.  If I connect multimeter to the white wire and the red wire and leave out the shield I get 8k.

[MarshallJMP]

Are both PU's irongear pickups?

If the bridge PU only has signal,ground shield wires you can't split them.

Seems like the bridge PU is wired in parallel?

What about the green wire?

[rabidgerry]

Oh no, silly me I meant to wipe that bit out.  The pickups are a dimarzio in the bridge and the original stock pickup that was in already.

So the dimarzio has the usual 4 conductors and a shield.

The switch right now functions as it should, it splits the neck and the bridge pickup when pulled but I get this shit noise when I touch the control.  Like when your finger touches a cable signal end.

Originally when I bought this guitar it had the two three wire pickups installed and also had the mod working without issue, but then I swapped the bridge out for a dimarzio.  Which then complicated things or made me screw up somewhere.

[MarshallJMP]

Is the pot chassis tied to ground?

[Kim]

The diagram will be misleading if you're using a DiMarzio pickup instead of the IronGear because the color codes aren't the same.  The IronGear in the diagram has the Green/White together, Black Ground while the DiMarzio needs the Black/White together, Green Ground.

[vansinn]

The diagram is using ground symbols, which should never be there!
All ground wires should must be connected to a single [ground-summing] point, usually on the volume potmeter chassis.
Solder a grounding wire from the tone potmeter chassis to the volume potmeter chassis.
From the volume potmeter, run a shielded cable to the jack socket.

Apart from this, the electronics cavity should be shielded, which should be connected to the volume pot chassis.

Do note that running a grounding wire from the tone potmeter and the switch chassis to volume potmeter [common ground summing point], can create a ground-loop if the potmeters are mounted onto cavity shielding.
In this case, it may be better to rely on the grounding of tone and switch chassis taking place through the cavity shielding The same grounding/shielding precaution applies to the jack socket: All cheap ones have non-isolating all-metal chassis.
Having such a socket mounted onto cavity shielding + running a shielded wire from vol potmeter to the socket almost certainly will create a ground-loop. Better use an isolated jack socket - and a shielded wire ;)

Great pickup wire color code chart, Kim

[rabidgerry]

Is the pot chassis tied to ground?

I'm such a dumb ass!  I think this is what the problem is!

I literally just took for granted the pot was grounded.  There is a good reason for this though I promise!  Normally I shield all my guitars, so no need to have a ground chassis wire because the pot is screwed down to the shielding and therefore correctly grounded.  This guitar has no shielding (yet) so the chassis still needs it's ground wire!

I will report back once I have grounded the chassis.

@Kim  Yeah man I'm all good with the dimarzio colour scheme.  As I mentioned the switch actually functions correctly, it's just I can't touch it without a noise happening, but when I let go it's ok.  Unless it's all the way down in which case there is a noise.

@Van Sinn  yeah you're right.  Normally I do shield the guitars, I just haven't bothered with this.  Had I bothered there wouldn't be an issue because the pot would be grounded by being screwed down to the shielding (I use copper tape).  As for ground loops, well schooled on this when it come to inside a guitar electrics, been doing it for years.

I'm positive MJMP has got the answer here, the pot has no chassis wire.  Already explained above though.  I shall report back!

[MarshallJMP]

ok keep us updated!

[rabidgerry]

That sorted the noise issue with me touching the Strings, but I must have damaged the pot some how?  I feel like I may have done something to it when I put the knob back on as it was really tight and I had to push very hard to get it down to the bottom.  Would this have caused damage?  So basically it crackles when I turn it the same way it would if say the pot needed cleaned (at least that's how it sounds to me).  So I don't know whether to use cleaner or replace the dam thing again (it is brand new).

What do you think?

But the initial noise of my touching the metal knob has been fixed so that's something at least.

[MarshallJMP]

I think you damaged it and it will need replacing.

[rabidgerry]

How can I push the knob on without damaging the pot?  If I lubricate the knurled bit of the pot then the knob will come off to easy  and could get lost so I'm reluctant to do that.

Any ideas?  I've always not known a safe way to put back knobs onto the pot shaft.  I think pushing the knob back on has damaged the pot internally.

[MarshallJMP]

From what you tell it looks that way, it can happen sometimes. When you turn it do you feel some mechanical abnormalities?

[rabidgerry]

Ok it's not the pot.

So the noise is not crackling like a worn pot.  When I take my hands of the strings and only touch the knob I get crackles touching it and it gets worse when I move it from 0 to 10.  When I put my hands on the strings and touch the knob it doesn't seem so severe and also I can turn it without much noise.

What the hell?  It's grounded.  See photo.

I'll try move the ground wire to the actual pot part of the push/pull as currently it's on tab which to me looks as though it's specifically for grounding.

[rabidgerry]

Moved it and there is no difference.  WTH is going on???

Really don't want to replace the whole goddam push/pull AGAIN.

There is no weird mechanical feeling when turning the knob, it's as smooth as butter to turn.

[rabidgerry]

Should I replace the whole thing at then jump?