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Post by ssjazzrock on Aug 15, 2006 6:56:22 GMT -5
Hello forum people, I replaced the stock pickups in my Squier '51 with: Dimarzio HS-3 in the neck Dimarzio Tone Zone in the bridge Now these are both hum-cancelling pickups, but the Tone Zone has a hum, which becomes almost a buzz with an effects pedal. To me, it seems like a grounding problem, but everything is grounded, there are no cold joints, and nothing is touching. The pickup doesnt really have a guard around it, so if I were to shield the cavity, would that make any difference? I did read on the guitarnuts site about shielding the actual pickups, but since this is all one piece (no seperate cover) I dont think that would work/look to good. And there are no fluorescent lights that could be causing this. Any ideas would be well appreciated. Thanks, Will
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Post by ccoleman on Aug 15, 2006 8:13:30 GMT -5
I would troubleshoot this by removing the Tone Zone and wire it directly onto a quarter inch plug and plug that into your amp and then into your effects pedal. It should be dead silent. If it is not, then you got a bad pickup. Now strike a tuning fork near it and it should pick up that A 440 Hertz. Progressively wire it back into your guitar circuit, one piece at a time, each step testing it for dead silence and pickup of the tuning fork. Eventually you should find some kind of ground loop. Solve it by star grounding and you're good to go!
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Post by ssjazzrock on Aug 15, 2006 8:51:09 GMT -5
wonderful... the HS-3 was dead when I first got it... now this one could be trouble... ugh
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Post by ssjazzrock on Aug 15, 2006 9:28:50 GMT -5
well, i just disconnected the pickup from the guitar, left it physically still in the guitar, took a pair of alligator clips and hooked it to a 1/4" jack, and there was the d@mn noise. So what ur telling me is that the pickup itself has a grounding issue?
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Post by ccoleman on Aug 15, 2006 9:42:42 GMT -5
The alligator cables might be picking up hum. You must eliminate this possibility: is the pickup connected (to the 1/4 jack then into your known good amp or fx pedal) with a SHIELDED cable ?? If not, do so, then listen and check if you get a quiet signal off that tone zone humbucker, then hold a vibrating A440 tuning fork near it (or other vibrating iron-containing metal) and listen to see if the pickup picks that up.
Other possibility is you incorrectly wired the two wires that lead to a single coil of the humbucker... single coils do make a buzz. Which 2 of the 4 wires of the tone zone did you use ??
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Post by ssjazzrock on Aug 15, 2006 9:54:19 GMT -5
ok, i tried the shielded cable, same result
i used the green and red wires
with the black and white soldered together and seperated from the rest
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Post by ccoleman on Aug 15, 2006 10:47:19 GMT -5
i dont know the DM wiring color codes but I assume you got that off their documentation .. if not, double check that.
next can u take it out of the guitar just to rule out the possibility that it's picking up hum from being installed.
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Post by UnklMickey on Aug 15, 2006 11:03:51 GMT -5
hi Ccoleman,
on a diMarzio, black and white are the series link, they should be connected together (and to nothing else).
red is hot, green is cold.
so his colors are right.
do you think this might be a good time to have Ssjazzrock do some resistance measurements?
unk
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Post by ccoleman on Aug 15, 2006 11:26:52 GMT -5
good idea unk.... ssjazzrock, do u have an ohm meter ??
measure each coil, (green to white/black junction, then red to white/black junction) they should be between 1000 and 5000 ohms.
infinite ohms means there is a break in the coil, zero means there is a short, and in either case the pickup is bad and DM should replace it for you free under warranty.
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Post by ssjazzrock on Aug 15, 2006 11:46:17 GMT -5
i do have a meter, and ill check it out
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Post by ssjazzrock on Aug 15, 2006 11:58:57 GMT -5
red coil clocks in at 8K green coil 9K
so the coils are good
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Post by ccoleman on Aug 15, 2006 12:40:42 GMT -5
I am stumped... the coils measure good so it should be cancelling hum, unless it was accidentally wound wrong (one coil is supposed to be wound backward of the other one, or the magnet is supposed to be reversed compared to the other magent, so to provide the hum cancelling feature... if it was not wound properly or the magnets not setup properly, then the hum would not cancel).
Can you call DM tech support at 800-221-6468. They should be open now (they run 9am-5PM NYC time). They should be able to diagnose it for you and suggest a fix. Post it here.
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Post by UnklMickey on Aug 15, 2006 12:50:43 GMT -5
hi Ssjazzrock,
i'm not totally convinced yet.
first, over 10% difference between coil resistances is more than one would expect.
but then, you only indicated to 1 significant digit.
you also need to check from the baseplate (or bare wire, if there is one) to any of the coil wires (red, black, white, or green).
the resistance should be infinite.
so should the resistance measurment from any coil wire to the pole-pieces.
any resistance will indicate a problem.
unk
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Post by ssjazzrock on Aug 15, 2006 15:15:08 GMT -5
ok, i rechecked the coils, one reads 7.97k the other reads 8.96k, in series they read out to 16.93k There was no measurement from the bare wire to any of the coil wires, nor from any of the coil wires to the pole pieces. Im starting to think that maybe im hearing things...
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Post by UnklMickey on Aug 15, 2006 15:44:50 GMT -5
i'm starting to think that your ToneZone has some of it's windings shorted together, or was wound with the wrong number of turns on one of it's coils.
if the coils have the same wire on them, you only have 89% of the turns on the red/black that you have on the white/green.
i doubt there would be that big of a difference in the resistance of the wire. (my guess is 98% to 102% would be reasonable).
so i believe the number of turns, is the issue here.
the closer the number of turns is to equal, the less hum.
DEFINITELY e-mail diMarzio, and get their opinion.
unk
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Post by ssjazzrock on Aug 15, 2006 15:57:54 GMT -5
ok, ill tell them about the difference in resistance between the two coils, then?
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Post by UnklMickey on Aug 15, 2006 16:09:09 GMT -5
sure.
either that, or just ask them how big of a difference in resistance between coils is "acceptable".
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Post by ssjazzrock on Aug 15, 2006 16:47:32 GMT -5
heres the reply I got: No. The readings are correct, and I don’t think there is any internal shorting. The TZ has a slightly higher hum level than vintage humbuckers because it has more wire than they do, which increases its sensitivity to external noise. If you feel the noise is excessive, please return the pickup to us to be checked out.
To me, any noise is excessive... if i had known this I wouldnt have bought the thing...
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Post by UnklMickey on Aug 15, 2006 17:54:16 GMT -5
well that certainly clears things up........................NOT.
i wonder if we might be able to get Wolf or someone else with a diMarzio X2N (supposed to be a HOT pickup) to give us resistance measurements from the 2 coils.
my gut is telling me they are gonna be a LOT closer.
then again, just sending it back with the statement you just closed your last post with, might lead to them offering other possiblities.
unk
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Post by ssjazzrock on Aug 15, 2006 18:24:46 GMT -5
well, unk I took the last piece of advice you gave there and told them how i felt. We'll see what they say... I have a feeling theyll say to add a capacitor or something like that. thanks for all ur help guys, this "hum" was something that was buggin me for a while now.
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Post by ccoleman on Aug 16, 2006 8:02:13 GMT -5
ssjazzrock, to achieve decent hum rejection... you want a 1% difference in the resistance values of the pickup coils, which will provide a maximum error of 1/100, or 40dB common mode (the induced hum) rejection.
For example 8020 ohms and 8100 ohms would be the max difference you would want to tolerate...
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Post by ssjazzrock on Aug 16, 2006 8:20:19 GMT -5
well ccoleman, I dont think DiMarzio knows that.
Or at least the guy who answered my email doesn't.
I should send it in anyway, not bother with this email crap, worst they do is either: a.) not send me anything back b.) send back the pickup with a note saying "We're sorry you are dissatisfied, but this pickup is the pinnacle of our perfection"
In either of those cases, Ill just use another humbucker...
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Post by ccoleman on Aug 16, 2006 8:26:21 GMT -5
I cant see why they would have such a problem making them closer... they have a coil winding machine which COUNTS the number of times it winds each coil... all they have to do is make each coil close to or the same number of windings, and it's all good. I bet you just got a bum pickup that got past the quality control guy or girl, definitely get another humbucker..
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Post by ssjazzrock on Aug 16, 2006 8:30:02 GMT -5
so, are you advocating me sending it in, or just getting another one entirely?
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Post by ccoleman on Aug 16, 2006 8:36:48 GMT -5
depends.. if you really like the tone but hate the hum, send it in and tell them you want one that has matching resistance on the coils down to 1%, and wait 2 weeks to get it back! if you want a working pickup sooner than that, I would bring it back to the music store where you got it, with your digital ohm meter, and try measuring another tone zone or other pickup, until you get matching coils to within 1% !
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Post by ssjazzrock on Aug 16, 2006 8:43:48 GMT -5
Uh, I guess Ill have to send it in to DiMarzio, I got this pickup online. The online store doesnt take returns on pickups. Ill wait for whatever it is DiMarzio sends me, Im in no hurry.
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Post by ssjazzrock on Aug 16, 2006 9:50:43 GMT -5
Ok, hows this for a message to send with the pickup:
I found this humbucker to be defective. It suffers from a 60 cycle hum. Please verify that the replacement pickup has matching coil resistances within 1% so that hum will not be a problem. Thank you.
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Post by UnklMickey on Aug 16, 2006 10:29:03 GMT -5
hi Ssjazzrock, that sounds reasonable to me. they might balk at the 1%, (i'll explain below) but i have no doubt, they can get way closer to that, than the 11% error you have now. I cant see why they would have such a problem making them closer... they have a coil winding machine which COUNTS the number of times it winds each coil... all they have to do is make each coil close to or the same number of windings, and it's all good. I bet you just got a bum pickup that got past the quality control guy or girl, definitely get another humbucker.. Ccoleman, even if the number of turns is exactly the same, there can be some difference in resistance. a looser wind, will mean more length in the wire used. that means more resistance. a difference in the purity of the copper in the wire will affect the resistance. a 1% increase in the diameter of the wire will mean a ~2% decrease in the resistance. (resistance is inversely proportional to the square of the diameter.) these increases in resistance with the same number of windings will have much less affect on the hum-canceling than would changing the number of turns by the same percentage. since these coils were almost certainly wound on different days, and/or different machines, with different spools of wire, i would not expect the resistance for the 2 coils with exactly the same number of turns to have exactly the same resistance. of course a 10% difference is a totally different story! here's ONE possibility on how that could occur with exactly the same number of turns being applied to each coil: the insulation on this wire is an enamel (essential paint) coating. as the wire is guided through the machine and onto the coil, there are many places where the coating can be scraped, or otherwise compromised. if 2 or more of these damaged areas touch, this will effectively bypass the windings between them. this could account for many lost windings. to further complicate matters, some damaged areas almost make contact with each other immediately after the winding process. it would be possible with age, for the last remaining bits of enamel dust that are separating them to shift. then they finally make contact. so you can now see how counting the windings is only part of the story. insuring that the resistances are the same (within reason) will also help. and even if the coils are "perfectly matched" when they go out the door, they might not stay that way. hope this helps, unk
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Post by ccoleman on Aug 16, 2006 10:53:35 GMT -5
unk, sounds cool.
some guys could care less about hum because they have super-shielded guitars and even single coils end up sounding dead silent.
in this case... ssjazzrock requires a humbucker that is a tight match... and DM should oblige his needs for 1% tolerance.
heck.... I bet they find one that is 1% after measuring the resistance on just a few pickups..
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Post by UnklMickey on Aug 16, 2006 11:22:32 GMT -5
...heck.... I bet they find one that is 1% after measuring the resistance on just a few pickups.. i hope you're right. human nature being what it is, i think they'll just grab 3~5 pickups and measure them. then send the best one of those, regardless of whether or not they meet the 1%. i really doubt they will put any more time than that into it. so keep your fingers crossed.
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