JP6 volume and tone change on middle P/U

[Unexplainedbaco]

Hi there, just got a JP6 second hand and when I switch to the middle pickup the volume
drops by half and sounds extremely thin and tinny. Anyone know what the issue could be?

Thanks!

 

[Kinjin]

The middle position on a JP6 is neck and bridge coiltapped, not full-on neck and bridge.

 

[Unexplainedbaco]

The tone is unusable. It sounds like a cheap radio effect plugin people might use when recording

 

[beej]

Sounds like it could be out of phase. Perhaps the original owner had other pickups and swapped these back in, incorrectly?

Best to have a look at the wiring and make sure the colours on the pickup wires match the labels on the PCB attached to the toggle switch.

Post a pic if you need a hand.

 

[Unexplainedbaco]

Here's a pic of the cavity. Looks like a ground wire is missing from the tone pot, could this be the culprit? It's just dangling there

 

[Unexplainedbaco]

Here is what I'm talking about. If it's not super obvious the last is the middle position and the volume drops probably by half and it's extremely brittle and thin. I'm certain that's not how it's supposed to sound.

 

[beej]

Yes, sounds like it's out of phase. The pickups aren't wired up correctly.

 

[beej]

Here's a pic of the cavity. Looks like a ground wire is missing from the tone pot, could this be the culprit? It's just dangling there

The dangling wire is a ground wire - it connects to the cavity cover, providing shielding when the cover is on.

What you need to look at is the wires where the're soldered to the PCB on the toggle switch. Btw, if you're not handy soldering, just take this to a local tech. This should be an easy fix.

 

[Unexplainedbaco]

The dangling wire is a ground wire - it connects to the cavity cover, providing shielding when the cover is on.

What you need to look at is the wires where the're soldered to the PCB on the toggle switch. Btw, if you're not handy soldering, just take this to a local tech. This should be an easy fix.

Im no pro but I have soldered a little before. I'm looking at the wiring and can't decide where it's been installed wrong, can you
Take a look?

 

[DrKev]

That's definitely an out of phase-like sound but the wiring does look good.

Which makes me wonder if one (or both) of the pickups are not the original DiMarzios? Other pickup manufacturers use the wire colors differently so what looks OK on the circuit board may not produce the correct result.

Standard wiring with DiMarzios should be north coil of bridge pickup and south coil of neck (the inner coils, if you will). With a clean tone, take a small screwdriver and gently tap the pole pieces to find out which coils are active in the middle position.

 

[Unexplainedbaco]

@DrKev

Ok I did and sure enough the inner coils are active. I noticed the wiring has a white sleeve with N (neck) B (Bridge) on them and they appear to be on the correct terminals as you said. What else could it be?

 

[DrKev]

Probably a problem with the switch. Is there a little blob of solder somewhere there shouldn't be? Check the underside of the circuit board too?



That both inner coils are working is good news and suggest the correct wiring and pickups, assuming the pickups are correctly installed and not rotated 180º. Also did you verify the pickups are DiMarzio and installed the right way around? Google "humbucker color codes" and see the possible other variations. Granted I am very sleep deprived right now (10 month old baby) but I can't see another brand pickup, wired as a DiMarzio should be, that could produce an out-of-phase inner coil.

 

[beej]

I'm no expert, but I think the phase of the neck pickup is different MM puts in there is different, vs replacement Dimarzios. I'm guessing if you crank up the gain on your amp you'll also notice a lot of hum in the middle position, which should be quiet. That suggests that the pickups have been replaced. (Or possibly the switch has? I don't know if they changed the wiring at some point or not.)

Anyhow, if so, you'll need to rewire the neck pickup so the polarity is reversed.

 

[Lou]

One of my JP's had a problem similar to yours. Very hollow sounding bridge pickup but not regularly. Everything looked fine. I had the wiring redone - basically undoing and resoldering everything and the problem went away.

 

[beej]

So this is one of those things you'll just need to play with. If you have what Kev and Lou describe, cleaning up the soldering should solve your problem.

If it's a pickup phase issue, then you could invert the wiring on the neck pickup. What I did was wire black to G, red to W, green to B and white to R.

Or, take it to someone who's handy with these things. It's hard to diagnose over the Internet

 

[T- Bone]

I thought the JP's were purposely wired out of phase to get that super clean tone in the middle position?

 

[beej]

The middle position of a JP is two coils in parallel. The signal is in phase, but the coils are reverse wound reverse polarity (RWRP) with respect to one another, so the hum they induce is out of phase. When you combine them, the noise cancels out.

This is the same principle used in humbuckers, strats, the Silent Circuit, etc. when in the split positions, etc. Pick 2 coils where one is RWRP with respect to the other and the noise will be out of phase and will cancel (regardless of whether you wire them in series or parallel).

What makes them sound cleaner is the reduced inductance of the coils (resistance and inductance decrease when you combine coils in parallel), which gives you a less middy sound (more highs and lows).