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  #1  
Old 04-26-2013, 11:06 PM
TFC TFC is offline
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help adding coil tap to PRS 5-way rotary

I've got a dual humbucker PRS with a 5-way rotary switch. In addition to the 5 sounds it gives me, I would like to add 2 more, if possible: bridge pickup split and neck pickup split. The rotary switch looks like this:



Any suggestions on how this can be done? Would replacing the tone pot with a push-pull pot help me get where I want to go?

I'm fine with soldering, but not too good at understanding how the wiring actually works (hence this question) so a schematic/picture/photo would be great. I've searched but haven't had much luck.

Thanks!
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Old 04-29-2013, 12:19 PM
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Clorenzo Clorenzo is offline
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I'd recommend doing this by replacing the original rotary with one of these (the 5-position, 4-pole one). IIRC I found a way to do it with the original one by cutting some tracks on the PCB and soldering wires directly to it but it's not easy and if you ever want to sell the guitar, you'll have to get a new one, which is insanely expensive.

With the one from Stewmac, yes, you can use a push-pull to have the normal PRS combinations when it's down and split the pickups in the neck and bridge positions when it's up. If this would work for you, let me know and I'll draw you a diagram.
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Old 04-29-2013, 01:11 PM
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Thanks for the response, Carlos. I'd definitely prefer not to alter the original switch, or take a chance at ruining it altogether, so the switch from StewMac looks pretty good. I'll definitely take you up on your offer to draw up a diagram. Thank you!
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Old 04-30-2013, 11:25 AM
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Clorenzo Clorenzo is offline
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Here it is. I assume you have 3-wire PRS pickups with black, white and red wires (the bridge red shown as pink in the diagram). The small cap between the input and output lugs of the vol. pot is the bleed cap that most PRS guitars have, the big one between the two pots is the tone cap (if it's wired differently, for example with a wire between the pots and the cap soldered between one lug of the tone pot and ground or any other way, you can leave it as it is.) SEE POST #9 BELOW FOR FURTHER CLARIFICATION ABOUT THE TONE POT WIRING

The rotary is shown as you will see it from the back when doing the wiring and I've drawn the two wafers separately for clarity. I've done the split so that the push-pull up leaves the coil closest to the neck active (for both pickups), which is usually the one that gives the best sound. If you want to split to different coils in either pickup, let me know and I can modify it easily.



I hope it's clear enough, if something isn't let me know. Happy soldering and let us know how it works out.
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Last edited by Clorenzo; 05-05-2013 at 03:42 AM.
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Old 04-30-2013, 11:43 AM
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Thank you!!! This is great. I really appreciate your effort in this. I will have to order that switch and give this a try.
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Old 05-04-2013, 04:42 PM
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The switch arrived a couple of days ago and spent a couple of hours today wiring this all together. When I finished and tested it out, I was very happy to hear sound coming out of my speaker! I'm getting all 5 sounds from the rotary and the coil taps work as well.

I do have one remaining issue. The tone control is not affecting the sound at all. It's as if it it not in the circuit. So, I must have missed a wire or possibly wired something incorrectly. Any thoughts on what I should check? The only thing I did differently from the diagram, is I wired the cap on the tone pot from the center lug to the side of the pot, which is how it is wired on the original pot that I replaced with the push-pull. Is there something else I should have done here?

If a photo would help, let me know what you need to see.

Thanks again, Carlos, for taking the time to create that diagram. I really, really appreciate your help!
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Old 05-04-2013, 05:53 PM
Lucidology Lucidology is offline
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Great post ... thanks!!
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Old 05-04-2013, 06:51 PM
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Great success! I re-wired the tone pot so that the cap was in between the middle lug of the tone pot and the lug on the volume pot (as depicted in your diagram) and it works perfectly.

For future reference, Carlos, you may want to clarify what you meant by "(if it's wired differently, for example with a wire between the pots and the cap soldered between one lug of the tone pot and ground or any other way, you can leave it as it is.)". This was the only part that wasn't perfectly clear (to me, anyway).

If anyone else wants to attempt this, I can verify that this works as expected. I used the 5-way, 4-pole switch from StewMac and a push-pull tone pot from PRS. The pickups I used are DGTs, but I assume this would work for any other 3-wire humbuckers from PRS that have opposite polarity, i.e. are meant to be used with a 5-way rotary.

Quote:
Great post ... thanks!!
Agreed
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Old 05-05-2013, 03:41 AM
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Clorenzo Clorenzo is offline
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I'm glad things worked out and sorry about the confusion with the tone pot wiring. First of all I should have shown the tone pot body connected to ground. This connection can be made directly on the body of the pot or, if it's a push/pull, on the tab at the top of the switch, which is easier to solder to and reduces the chances of damaging the pot from having to apply too much heat for too long. So, the diagram should have looked like this:



TFC, I don't know if you've made that connection but the control cavity probably has conductive paint, so the pot is grounded, although maybe not very effectively (most PRS guitars I've seen have just one thin coat of paint), so just to be sure, connect a wire from the tone pot body or switch tab to the back of the vol. pot if you haven't done it already.

Just to clarify the tone wiring further: there are several ways of wiring a tone pot, of which PRS has used at least three, depending on the model / year:

1 - As shown in the diagram
2 - As shown in the diagram but with the tone cap going to the output (middle) lug of the vol. pot rather than the input lug. This is "50's wiring", which IMO is overkill when you already have a bleed cap which is more effective reducing treble loss and has no "side effects", see post #5 in this thread
3 - With the tone cap between the middle lug of the tone pot and ground, and a wire between the left lug (the one shown in the diagram connected to ground) and the input lug of the vol. pot

2 and 3 are shown here. Note that in the "Pre-2007" version the two "red wires" that go to the rotary from the vol. and tone pots are actually connected together at the PCB, so it's as if there was a wire directly between the tone and vol. pots. TFC, this may have been the reason why your first attempt didn't work: if you just removed that wire from the tone pot to the rotary, because there wasn't one in the diagram, and no wire directly from tone to vol. pot (as I said there would be but actually there isn't), then the tone control wasn't actually in the circuit.

Note also that 1 and 3 are effectively equivalent: the tone pot and cap are in series and it doesn't make a difference whether it goes vol. pot -> tone cap -> tone pot -> ground or vol. pot -> tone pot -> tone cap -> ground, so the way you've finally done it, the tone pot will work exactly the same as it did before.

I've edited the previous post referring to this one in case someone else finds this useful. And as you said, yes, this will work with any 3-wire PRS pickups, like Dragons, Vintage/HFS and some versions of the 57/08s, but not with the ones that have a shield, a hot and a coil split wire, like some other versions of 57/08s or McCarty's.

If someone wants to do this with non-PRS pickups, see this thread.
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Old 05-05-2013, 05:14 AM
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Thanks for the clarifications. I didn't ground the tone pot, but the cavity in my guitar is shielded, as you said. I'll have to go back in and add the ground wire. Great info here.
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