P-Roblems with my P-Rails

B

Bobisadrummer

New member
So I installed a set of P-Rails w/ triple shots in my Chapman ML-3 which has 24 frets. I have them flipped so the rails are outward. I have a 4 way blade for series and parallel middle positions. My volume pot is a push/pull pot that when pulled, bypasses both the volume and the tone pot kind of like a blower switch, but it still takes into account my pickup selection, though I'm not sure if it takes into consideration the phase switch. The tone push/pull pot switches the phase of the bridge P-Rail. I also have the capacitor wired for 50's style so I don't lose high end when rolling back the volume. So my problems are I'm not getting the hum cancelling effect in certain positions/combos that I thought I should be.

I get hum cancelling, as I should with the following:
Bridge position, series or parallel via triple shot.
Neck position, series or parallel via triple shot.
Bridge+Neck position Parallel while both pickups are in humbucking mode via triple shot in phase and out of phase.
Bridge+Neck position Series while both pickups are in humbucking mode via triple shot in phase and out of phase.

I'm getting hum cancelling, which I don't think I should with the following:
p90 bridge + rail neck in phase.
rail bridge + p90 bridge in phase.
p90 bridge + p90 neck out of phase.
rail bridge + rail neck out of phase.


I'm getting hum, which I shouldn't be with:
p90 bridge + p90 neck in phase.
rail bridge + rail neck in phase.
P90 bridge + rail neck out of phase.
rail bridge + p90 neck out of phase.

Basically, I'm not getting hum cancelling effect from the middle positions when the pickups are running in match single coil mode in phase though from what I've read, I should be. I'm only getting the hum cancelling when I switch the phase of the bridge pick up. Am I wrong? It could be my wiring. I've actually commission two diagrams and I have contacted both people I got the diagrams from, one suggested I have the ground and hot wires reversed somewhere, probably the phase switch. I'd post the diagrams but I'm not sure if they'd appreciate their work being posted online :( The bridge pickup is also wired to the tone pot for the phase switch.
 
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Re: P-Roblems with my P-Rails

Also, I notice that with the bridge PRail and Triple Shot, the switches activate whichever coil they are switched in the direction of where as the neck is kills the coil of which the switches are switched in the direction of. If I want to make it so the neck behaves the same as the bridge, do I swap the red/black and white/green wires on the pad?
 
Re: P-Roblems with my P-Rails

Do you have a diagram and some pics of the control cavity for this? We have some really great wiring wizards here that can help out if you provide these 2 things.
 
Re: P-Roblems with my P-Rails

Your bridge P-Rail works "correctly" as I like to wire my Triple Shots because you mounted the pup "correctly" with the Rail toward the bridge. I could never understand SD's reasoning to have a pup's coil active when the switches in the TS are pointed AWAY from that coil.

Anyway, there is an alternate wiring scheme included with your TS. Using that wiring will make your neck pup function like the bridge pup (the switches point toward the active coil, when the switches point together the pup is in series, when they point away from each other the pup is in parallel).
 
Re: P-Roblems with my P-Rails

Mincer said:
Do you have a diagram and some pics of the control cavity for this? We have some really great wiring wizards here that can help out if you provide these 2 things.
Click to expand...

Here's one version of the diagram I have.
View attachment WiringDiagram-ML3.pdf

Here's another version.
63433.jpg

Here's some pictures of the wiring, mainly the phase switch on the tone pot.
http://imgur.com/a/ZZ3mi

GuitarDoc said:
Your bridge P-Rail works "correctly" as I like to wire my Triple Shots because you mounted the pup "correctly" with the Rail toward the bridge. I could never understand SD's reasoning to have a pup's coil active when the switches in the TS are pointed AWAY from that coil.

Anyway, there is an alternate wiring scheme included with your TS. Using that wiring will make your neck pup function like the bridge pup (the switches point toward the active coil, when the switches point together the pup is in series, when they point away from each other the pup is in parallel).
Click to expand...
Now that won't invert the series/parallel functions right? Series will still be both switches inward and parallel outward?
 
Re: P-Roblems with my P-Rails

To get the functionality that you want, swap the black and red wires, and swap the green and white wires (from the standard wiring on the TS).
 
Re: P-Roblems with my P-Rails

So Mike from Guitarelectronics suggested my hum problems might be an issues with the bridge p-rail's internal wiring and magnetic polarity. Could it be something to do with how SD has the bridge p-rail wired so it works with the switches activating the coil they're switched to instead of how the neck works?
 
Re: P-Roblems with my P-Rails

Regarding hum in the middle position with like type coils, you would think
that this should not be so, certainly at the design level.
You would expect the two rails and P90's to be hum free when switched together,
like a Strat or LPJunior.
How easy is it to flip the magnet?

Also, are you using the Stewmac funky no-load volume pot?
It uses some tricky grounding paths.
 
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Re: P-Roblems with my P-Rails

Will S-T said:
Regarding hum in the middle position with like type coils, you would think
that this should not be so, certainly at the design level.
You would expect the two rails and P90's to be hum free when switched together,
like a Strat or LPJunior.
How easy is it to flip the magnet?

Also, are you using the Stewmac funky no-load volume pot?
It uses some tricky grounding paths.
Click to expand...

I'm using Bourns push/push pots.
 
Re: P-Roblems with my P-Rails

Also, I wanted to do 50's wiring as to not lose treble with the volume back off? Which lugs do I solder the capacitor to? One diagram I have has it solder to both of the middle lugs, the other has it wired to only the middle lug on the volume pot and one of the outer lugs on the tone pot.
 
Re: P-Roblems with my P-Rails

Your original post has where you're getting hum and not. That would seem to be where I would expect it to be. If the PRail as a whole works in series and parallel in phase, then each rail and each p90 will have the same polarity and magnet orientation. So combining similar pickup types will give you 2 coils of the same magnet orientation and therefore no RP effect. So what you have is dead correct. If you reversed the phase of the bridge, you would find the hum cancelling would apply to the reverse options.

50's wiring is all to do with where the tone circuit is connected to the volume pot, and nothing else. It has to be connected to the output lug if the vol pot, where the connection to the switch hot is.
 
Re: P-Roblems with my P-Rails

AlexR said:
Your original post has where you're getting hum and not. That would seem to be where I would expect it to be. If the PRail as a whole works in series and parallel in phase, then each rail and each p90 will have the same polarity and magnet orientation. So combining similar pickup types will give you 2 coils of the same magnet orientation and therefore no RP effect. So what you have is dead correct. If you reversed the phase of the bridge, you would find the hum cancelling would apply to the reverse options.

50's wiring is all to do with where the tone circuit is connected to the volume pot, and nothing else. It has to be connected to the output lug if the vol pot, where the connection to the switch hot is.
Click to expand...
According to this post by Frank, the p90's and rails should be hum canceling.

The output lug is the center lug correct? the right most lug is the input? So I should have it wired to Vol output and Tone input?
 
Re: P-Roblems with my P-Rails

If they are doing the opposite, then you most likely have one that isn't........maybe you have 2 of the same position.

Anyhow its not something you will necessarily be able to do anything about save for a return.......if you flip mags then the rail and p90 mags will be OOP in the same pickup methinks.
 
Re: P-Roblems with my P-Rails

AlexR said:
If they are doing the opposite, then you most likely have one that isn't........maybe you have 2 of the same position.

Anyhow its not something you will necessarily be able to do anything about save for a return.......if you flip mags then the rail and p90 mags will be OOP in the same pickup methinks.
Click to expand...
Well, not only am I getting a new set from Prymaxe because the little ribbon wire on the neck triple shot became detatched, but I also ordered a trembucker one, which is the proper size for the guitar I was putting them in. Also ended up grabbing a second neck prail so I can put the replacement set from Prymaxe into something else. This also gives me some time to deepen the pickup cavity. So far I'm having the worst luck with putting these in my guitar, but I'm determined to make it work. I loved what I heard for the half a day I got to play them a bit.
 
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Re: P-Roblems with my P-Rails

So if anyone is interested in an update, I just finished all the work on the guitar. I routed out the pickup cavities making them deeper to accommodate the P-Rails being taller than the stock pups. I ended up rewiring everything from scratch while switching the wires on the Neck Triple Shot ring so they work like the bridge. After some preliminary tests with tapping a screwdriver on the pickup polls to check the switches were working I strung it up and...

EVERYTHING'S WORKING AS IT SHOULD!

All that's left is a good set up and to fine tune the pickup distance and shielding. Once the conductive paint and copper tape arrives later this week, I'll go ahead and give it a good overkill shielding to eliminate almost all RF/EMI noise.

The only thing I'm not certain of is if I did the 50's wiring properly. I attached the capacitor to the lugs as shown in this diagram and I'm not sure if I can tell if I'm losing treble because the volume cuts out so quick.
Jan14_PG_CLM_ModGarage_image2_WEB.jpg
 
Re: P-Roblems with my P-Rails

Great to hear all's well. 50's wiring is simply attaching the tone circuit to the output of the vol pot......as is shown in the above diagram. The various methods of wiring the tone pot/cap are immaterial operationally, if you should choose to convert any other guitars with existing tone pots already wired in.

As to the vol drop, thats all in the taper of the pot you have bought. Those who love volume swells go for this type of pot. Those who like more fine-tune to ride the dirt/clean interface with single channel amps tend to go for a more even rolloff.
 
Re: P-Roblems with my P-Rails

I am happy you got it working. This sounded like quite a project! How does it sound?
 
Re: P-Roblems with my P-Rails

It's great, a little brighter than what I'm normal used to, humbuckers. I've noticed though, that my neck pickups signal is never completely cut. When I have the pickup in the bridge position, the neck pickup is still active, not full bore, but still active. When I'm in the neck position though, the bridge is completely killed. Not sure if it's a problem with the wiring or maybe I need to file out the slot for the blade.

I have it wired up like the switch on the right.
custom4way.jpg
 
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