59/09 pickup swap - Help!

[JdS]

Hi guys,

I just replaced the 58/15's in my 2019 McCarty (single conductor wiring) with 59/09's (four conductor), using this schematic: http://www.prsguitars.com/documents/custom3waytoggle.pdf

I installed the pickups exactly like the schematic:

Bridge pickup
- black wire (hot): to 3way toggle, right top lug
- red wire (split): to tone pot, right bottom lug
- white wire (ground?): to tone pot, right top lug
- silver braid (ground): to back of volume pot

Neck pickup
- black wire (hot): to 3way toggle, middle top lug
- red wire (split): to tone pot, left bottom lug
- white wire (ground?): to tone pot, left top lug
- silver braid (ground): to back of volume pot

Sadly, there's no signal from the neck pickup. Could the schematic be incorrect? I'm pretty good at soldering so I don't think it's the connections.

I deviated from the schematic in 2 occasions, maybe that causes the problem:
- I kept the 1.1k & 2.2k resistors on the push/pull tone pot. They were already in the McCarty and I figure they'll fatten up the split coil sounds.
- the outer braid of the output-jack cable is also soldered to the back of the volume pot for extra grounding.

Could someone take a look and point out where I went wrong? Any help would be greatly appreciated!

 

[Malloc]

I think you might actually want to do this assuming a single push/pull tone:

Basically, that custom wiring diagram isn't compatible with coil shunting for both pickups - it's switching the neck hot to series link instead of dumping it.

 

[JdS]

Great input, thanks! So on the neck pickup the white wire is hot, while on the bridge it’s the black one? I guess PRS likes to complicate things a bit.

I forgot to mention that i also installed the McCarty multi conductor drop-in set. Assuming that this was necessary for four conductor pickups.

https://us.prsaccessories.com/products/mccarty-drop-in-dual-conductor

Does this affect your suggestion?

 

[Malloc]

That kit isn't compatible with the diagram I posted, but it should work with the one you originally posted.

Your problem is likely trying to involve the original resistors with neck pickup since it's not a coil shunt split.

You can certainly modify it like I've shown to make both pickups coil shunt with the only side effect being I think you'll get the slug coil from both instead of bridge slug and neck screw.

 

[JdS]

Alright, I just made a second attempt. I kept my initial configuration but removed the resistors on the tone pot, like you suggested. Both pickups now work in humbucking and split mode and they sound great!

A new problem however: there’s a pretty noticable noise in humbucking mode. When i split the pickups, the noise goes away. It’s not ground noise but more like 60 cycle hum.

another curiosity: when i split the bridge pickup, it’s a recognisable and great sounding split sound but both coils are on. Both slug and screw coil make an equal amount of sound when i tap them. In the neck pickup I only get the screw coil, which is the correct way to go I believe.

 

[Malloc]

Can you post a picture of the tone pot wiring? Sounds like the bridge split control may be backwards if you get sound from tapping on both coils when you think it should be split (assuming no resistor in place)

 

[JdS]

Sure, here are a few pics:

https://pasteboard.co/JL14k0a.jpg
https://pasteboard.co/JL14BW5.jpg
https://pasteboard.co/JL14Mgp.jpg

It might be a bit hard to see in the pictures but the wiring is exactly like I described in my original post, without the 1.1k & 2.2k resistors:

Bridge pickup

• - black wire (hot): to 3way toggle, right top lug
• - red wire (split): to tone pot, right bottom lug
• - white wire (ground?): to tone pot, right top lug
• - silver braid (ground): to back of volume pot

Neck pickup

• - black wire (hot): to 3way toggle, middle top lug
• - red wire (split): to tone pot, left bottom lug
• - white wire (ground?): to tone pot, left top lug
• - silver braid (ground): to back of volume pot

https://pasteboard.co/JL130mv.png

1 difference with the 3way toggle diagram is that the tone cap from the tone pot (middle bottom lug) goes to the left lug on the volume pot, instead of the middle one. This was pre-wired in the drop in set.

 

[Malloc]

I don’t see anything obvious from those shots. You have a multimeter? Easiest way to diagnose would be to ohm out all positions.

 

[JdS]

I do but i have no working knowledge of electronics. Could you guide me through the process? Or point out what i need to look for? thanks!

 

[Malloc]

Set the meter to ohms, set volume+tone wide open, put in a cable and touch one meter end to the tip and one to the ground sleeve.

You should see around 9k for bridge in humbucker mode and ~8k for neck (somewhere around half of that for each in split mode). I’d run through the positions with and without split then report back.

*note: mine has resistor mod so it’s not exactly half the impedance in split mode

 

[JdS]

Ok, very clear, thank you. Beautiful guitar, you got there!

Measurements:

• bridge humbucking: 9.24k
• bridge split: 4.68k
• neck humbucking: 8.29k
  
• neck split: 4.17k

No problem there I guess.

 

[Malloc]

Hmmmmm nothing unexpected there. Does the sound get better or worse if you touch the strings?

 

[JdS]

It get's a little better. The typical grounding buzz disappears when I touch the strings.

The '60 cycle' type noise however remains and only disappears in the middle split position. It's the only position in which the guitar is quiet, as it should be.

 

[Malloc]

Got me stumped trying to diagnose remotely. Last time I had a similar problem was when there was an ungrounded shield leaking into the hot, but I don’t really see anything obvious in your photos. Maybe poke around some continuity checks between hots and shields.

 

[JdS]

Hey Malloc, I still haven't been able the fix the noise and bridge split issue. I think i'm going to try and wire it up like you suggested in your original reply. One question here though: what do I do with the remaining white (bridge pickup) and black (neck pickup) wire?

 

[Malloc]

Ground them wherever is convenient. One thing you might check: swap the connections on output jack or at least verify hot and ground aren’t switched. I accidentally did that to myself with a Strat the other day and it behaved exactly like you’re describing which leads me to believe you almost certainly have the shielding absorbed 60Hz coupling getting into hot somehow.

 

[JdS]

The output jack turned out to be fine so I pulled out the multi conductor wiring and put the old single conductor set back in. I wired it following your suggestions and at last, everything sounds the way it should. Fat humbucking tones, sweet splits and quiet as can be. Thanks for all your help. really appreciate it!

https://pasteboard.co/JPRLOHr.jpg