Pickup Woes :(

delorean

So I thought I had found my perfect pickup set recently – Seymour Duncan YJM Fury (stacked single coils).

 

However, the guitar they are in has suddenly started to make an horrendous buzzing sound when the amp is cranked up and on the dirty channel.  It’s completely unusable.

 

My normal tech is booked for weeks in advance so I can’t take it back to him just yet, so I gave it to the guitar tech where I work and he’s had a look.  He’s managed to reduce the buzzing a little by re-doing the grounding, but it still sets off if there are electronics close by.

 

Any ideas what the problem could be?

sweepy

Obvious I know, changed guitar, lead, mains socket ? Phone nowhere near the amp/guitar etc. ?

paulnb57

A couple of questions
Did you install the new pickups?
Were just the pickups wired in or a complete rewire?
Did it hum before the swap?
Has it always hummed since they were changed?

delorean

I didnt install them myself, it was done by my tech - he did the 3 pickups, plus a new volume pot and a treble bleed mod.

Before the swap it was just the usual 60 cycle hum of regular single coils.  At low volume (living room levels) I never noticed any noise, it was only after plugging into my main amp and cranking to gig level that it became glaringly apparent. 

I've tried different cables and 2 other amps, in 3 different locations (so definitely different mains sockets) but no joy.   Phone is also well away from the amp to prevent interference. 

Funkfingers

Remote diagnosis will be greatly eased by photographs of your soldering and of the output conductors where they leave each pickup bobbin. 

delorean said:
Seymour Duncan YJM Fury stacked single coils ... the guitar they are in 

What guitar, exactly, are the pickups in? (If, for example, your guitar is a Fender MIM Stratocaster with a mid booster, this could contribute to the problem.) Any trick wiring of the controls? Most specifically, any attempt at coil splitting of the stacked pickups in selector switch positions 2 and 4?

If you do have any automatic coil splitting, your choice of "hot" conductor becomes critically important. Splitting to leave only the lower coil of a stack in circuit will result in a very weak signal. Cranking the amplifier to compensate for this will raise the noise floor.

Funkfingers

delorean said:

 a new volume pot and a treble bleed mod.

What taper and nominal resistance value is the pot? 

Is the treble bypass mod just a capacitor or a cap/resistor network?

timhulio

delorean said:

 it was done by my tech 

Take the guitar back to this tech and tell him to fix it for free. If he's busy for weeks ahead ask him to sort out your guitar first.

ICBM

Does it do it in all the individual pickup positions?

How are the pickups wired up? (Which wire colours to where?) These have four-conductor cabling, and if they're connected wrongly then they will increase noise rather than cancel it.

Does the buzz change if you're touching the strings or not? If not the ground wire to the bridge or trem claw has come off. If it gets *louder* when you touch the strings either some other ground connection has come off or the jack wiring is reversed.

Funkfingers

ICBM said:

ground connection has come off

Eureka!

If the guitar tech installed a new volume pot, it is possible that he forgot to reconnect the vibrato claw ground wire. 

ICBM said:

How are the pickups wired up? (Which wire colours to where?) These have four-conductor cabling, and if they're connected wrongly then they will increase noise rather than cancel it.

Good shout.

Malmsteen currently endorses Duncan. In the past, he endorsed DiMarzio stacked coil replacement pickups for Stratocaster. The two designs follow the same basic principles and use the same four conductor coding colours BUT not in the same order.

If the tech has tried to wire Duncan pickups as if they used the same colour codes as DiMarzio, the pickups will not reject noise in any of the selector switch positions.

delorean

Thanks @Funkfingers ;

It's a US Standard Strat, nothing fancy going on that I'm aware of and no coil taps etc. 

The volume pot is the Seymour Duncan Yngwie Malmsteen speed pot : 500k, audio taper.

The treble bleed is this (in my tech's words as this is where I get lost!):  "The treble bleed mod is made up of a 0.001uf cap plus a 150k resistor.  I'll use a sprague orange drop cap."

I've just taken a load of photos - hopefully this means more to you than it does to me!

https://drive.google.com/folderview?id=1glh_9FG1UFU5kHHjZILE5dZD9qd1gtLD

delorean

wow thanks for all the suggestions guys! 

Hopefully the above photos will shed done light!

Funkfingers

Shoulda used the 250k version of the speed pot. 

In my opinion, the treble bypass is redundant.

If your lower tone control is a TBX, it may be contributing to the problem.

delorean

ICBM said:

Does the buzz change if you're touching the strings or not? If not the ground wire to the bridge or trem claw has come off. If it gets *louder* when you touch the strings either some other ground connection has come off or the jack wiring is reversed.

Just re-stringing now so I'll check and report back!

delorean

Funkfingers said:

Shoulda used the 250k version of the speed pot. 

In my opinion, the treble bypass is redundant.

If your lower tone control is a TBX, it may be contributing to the problem.

Ooh - I asked Seymour Duncan before buying the pot and they suggested the 500k pot (as these as are stacked coils). Do you reckon that's wrong?

No TBX on this guitar, just standard controls

ICBM

Funkfingers said:

If your lower tone control is a TBX, it may be contributing to the problem.

It's not, it's a standard tone pot. The tone pot casings are not grounded though - they're relying on the foil on the pickguard. This *usually* works, but I would still add a wire - there has been one before, judging by the solder on the backs of the pots.

The wiring I can see appears to be correct. What is the wiring at the jack like?

Why is the shielding foil under the pickups not connected to the ground screw? It needs to be to serve any purpose. The guitar probably has shielding paint under the colour coat which the screw is supposed to make contact with, but it doesn't always very well. If it's not, then the ungrounded foil could be acting as an aerial.

delorean

Thanks @ICBM - just uploading pics of the input jack wiring now - same link as above

That shielding foil wasn't there before - today is the first time I've seen it, so the tech must have added it when he did the pups

Funkfingers

delorean said:
I asked Seymour Duncan before buying the pot 

Who did you ask? Their useless UK distributor, their useless customer support staff or their useless Facebook site and User Group forum staff presence?

There are several wise and helpful registered members on the Seymour Duncan User Group forum. They consistently give better replies than anyone on the company payroll. (Zhang, ArtieToo and hermetico immediately spring to mind. LtKojak flips between being helpful and flying into Italian rages.)

delorean said:

they suggested the 500k pot (as these as are stacked coils). Do you reckon that's wrong?

Yes because it is a Stratocaster. 


Looking at your photographs, I am concerned about the metal sheets on the floor of the swimming pool pickup cavity.

• Are these fastened to anything? 
• Are they grounded to anything? If not, what possible contribution can they make to screening?
• With the pickup assembly in place, do the pickup height adjustment screws or the copper foil on the underside of each pickup touch the "screening" metal sheets?

sixstringsupplies

 He’s managed to reduce the buzzing a little by re-doing the grounding, but it still sets off if there are electronics close by.

 

Any ideas what the problem could be?

As pointed out by @ICBM and @Funkfingers I would ground the pots together as the foil underneath pickguards isn't reliable and the fact that going near electronics sets it off indicates a shielding problem.

delorean

Thanks for all of the advice and comments guys - my tech has said he'll take it today and look it at over the course of the next week for me. 

I really hope he can sort it as he has set it up soooo well and it feels wonderful to play, it's just the 'small 'matter of the amplified sound.

Also @Funkfingers - apologies, I just checked and the YJM pot in my strat IS the 250k version which was indeed what SD had advised me.

delorean

Good news - my tech called me last night to say it was all sorted.  He asked me to bring my amp with me to test it.  Got there, plugged in and all good!

With my limited understanding, here's the gist of what I could grasp - Apparently there was so little space in the cavity under the scratchplate that a wire had gotten caught (or something).  A bit of jigging about and everything is now seated in the cavity properly - and the noise is gone.

Turns out all I really needed was a nice chap to fill my cavity...