Pickups change tone control function

B

Bladefish

New member
Question for the group. I have a Squier Strat that had Jackson and Schaller humbuckers in it with master volume and master tone, and they worked fine. In fact, before that, it had a pair of SD humbuckers, too. Found used SD TB-6 and SH-1N and swapped out the Jackson and Schaller for them. Now for some reason, dialing down the tone control makes it sound very nasal and almost out of phase, and the volume drops too. It is no longer acting like a tone control. I replaced the tone pot and cap to make sure, but it still does the same thing. I did the standard SD wiring (red+white together, black to hot, green+bare to ground). Anyone ever seen or heard this before?

Thanks for any help.
2H_3G_1V_1TppSPL.jpg
 
Re: Pickups change tone control function

Are you wired with a pull push switch like in the diagram? Could you post a picture of the open control cavity so we can see the wiring?
 
Re: Pickups change tone control function

Sorry wrong diagram. I DO NOT have a push pull pot. Just the standard SD 2 humbucker/master vol/master tone wiring. Like I said, nothing after the toggle switch changed, just different pickups. When vol & tone are full on, no issues. As I turn down the tone control, it gets more nasally and weaker signal. When tone is all the way down, it sounds almost out of phase. This is all with any pickup combination, including each pickup individually.
 
Re: Pickups change tone control function

Chances are you have the tone capacitor wired to the output instead of ground, making it so it works as a bass cut instead of a treble cut.
 
Re: Pickups change tone control function

Christopher, I followed the SD diagram, which I've done on many guitars. So the cap is wired to ground, per the diagram. And the tone control works fine with different pickups in this exact same guitar.
 
Re: Pickups change tone control function

Send a picture of the control cavity, that will be the easiest way for us to figure it out.
 
Re: Pickups change tone control function

So I put the pickups that I had in that guitar previously (Jackson/Schaller) and the tone control magically works fine now. It is definitely something to do with those used SD pickups. I guess I'll have to get a meter and learn how to identify pickup wiring and polarities.
 
Re: Pickups change tone control function

Well, the wiring is pretty simple- red & white are the series link (usually joined together) while green/bare are ground, and black is hot.
 
Re: Pickups change tone control function

Mincer, that is exactly what I did with these SD pickups. In fact, I had an old SD JB in there at one point and it worked fine. Just these 2 particular used SD pickups that I put in there cause the tone control to act goofy. I wonder if somebody rewired them with a different color scheme. But it still doesn't explain why it would affect the tone control that way, unless someone knows something that I don't.
 
Re: Pickups change tone control function

You don’t even need a meter really. Separate the leads from the solder joints and start from grounding the green and making the red hot on the pickup. Tap the pole pieces with something metal. You should only really hear the slotted screw coil. If you don’t then the colored leads were modified. Just step through the leads until you find the right pairs. Although checking the wires probably wouldnt solve anything as you would probably have heard phasing issues from the pickups if the tone was all the way up.

Somewhere somehow there is either a grounding issue or a cap issue.

Are both sets of pickups being soldered in the same places on the pots and switches?
 
Re: Pickups change tone control function

Bowtomecha, nothing past the toggle switch is being touched here, except when I replaced the tone pot and cap for troubleshooting. Both sets of pickups were wired in exactly the same lugs on the toggle switch. The 2 SD pickups that were causing the issues had very short leads so I soldered and taped off the red+white on each pickup, connected the green+bare from each pickup together, then extended those to ground with new wire. Then I extended the black lead from each pickup with new wires and then connected those to the toggle switch lugs. I made sure to tape off every connection carefully so that nothing was exposed. This is something that I've done many times with short pickup leads.
 
Re: Pickups change tone control function

So strange. And this happens with the sd pickups no matter what position the pickup switch is in?
 
Re: Pickups change tone control function

What you describe MIGHT be a case of "capacitive pickup(s)": the wire of some coil(s) is broken but stays aligned with itself and behaves like a series capacitor.

That's something that I've met (and repaired) more than once, and TWICE for a same musician (!).

Symptomes:

-the sound is very tight, with less bass than usual;

-the tone pot works way less well as a low pass filter but increases the tightness of the tone and simultaneously reacts like a volume control;

-the pickup(s) give(s) no or infinite DCR reading but exhibits a capacitance (of 4nF approximatively, most of the times, IME). A normal pickup would do the contrary.

Such pickups are playable: Roy Buchanan did a whole career with a Telecaster (Nancy) hosting a capacitive bridge pickup - and some say that the pickup of the Frankenstrat used in VH1 had also a broken capacitive coil.
They just don't cooperate with tone controls...

Of course, if the DCR readings are normal, the problem is elsewhere. :-)
 
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Re: Pickups change tone control function

Bowtomecha, there is no increased noise.

Freefrog, you're talking over my head, but the sound that you describe is pretty close to my situation. Weird that it would happen to both pickups, but I guess they came off of the same guitar. The poles are rusty as hell, but I was hoping that it did not affect sound. What is the fix for this?
 
Re: Pickups change tone control function

Try wiring each pickup directly to the jack to see if you are getting both coils working.
 
Re: Pickups change tone control function

Bladefish said:
Freefrog, you're talking over my head, but the sound that you describe is pretty close to my situation. Weird that it would happen to both pickups, but I guess they came off of the same guitar.
Click to expand...

Hello,
Sorry for the delayed answer. Yes, it would be weird to find this "rare" problem in two pickups simultaneously but as I said, a musician that I know has got this problem two times in a few years, in two different guitars.

The poles are rusty as hell, but I was hoping that it did not affect sound. What is the fix for this?
Click to expand...

The fix for the poles is to sand them if not to change them but in humbuckers, poles are not touching the coils so they have nothing to do with the integrity of the wire.

Now, corroded poles suggest that the mentioned pickups have suffered of agressive conditions and even if Duncan's are not especially fragile ( https://www.seymourduncan.com/blog/the-tone-garage/the-infamous-pickle-jar-pearly-gates ), any coil can be harmed when mistreated. I've got my share of pickups stopping to work, even without apparent reason sometimes.

There's no easy fix for capacitive coils due to broken wire except peeling the first layers of the dead coil(s) or rewinding the PU.

That said, my hypothesis is not necessarily right: to check it, I'd try to measure the DCR of your pickups with a multimeter...

I hope that you'll solve your issue. Good luck!
 
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