Question about strange DCR reading on Fender CS 51 Nocaster neck p/up

Discussion in 'Just Pickups' started by theprofessor, Mar 25, 2020 at 12:10 PM.

  1. theprofessor

    theprofessor Friend of Leo's

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    Hi all -

    I have a Fender 51 Custom Shop Nocaster neck pickup, which I like very much. I recently took it out of a partscaster and measured it before packing it away. When I measure at the ends of the leads, I get a DCR starting off at about 11k and climbing all the way up to about 13.7k. The multimeter just keeps roaming.

    When I measure at the eyelets, I get a reading that is very close to the Fender spec sheet: about 7.2k.

    What does this mean?

    At some point, I tried to de-solder the ground strap running from one of the eyelets to the ground tab on the cover, so as to remove it completely. I wonder if somehow I messed something up when I was yanking on that thing, trying to get it out. I ended up just cutting it off, but I have thought that perhaps I damaged the coil wire to that eyelet or something else.

    But if I understand correctly, if the coil wire were broken anywhere, I would get a reading of "0."

    Anybody have any ideas? Can the leads lie, while the eyelets tell the truth?
     
  2. Teleterr

    Teleterr Friend of Leo's

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    Sounds like an intermittent short. It might be where you said or a break in the lead. Anything on the lead end, wax etc such that the ohm meter leads aren't making good contact ?
     
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  3. theprofessor

    theprofessor Friend of Leo's

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    The only thing on the lead-ends is solder. I am getting good contacts there without interference, and I just got an initial reading from the lead-ends of 10.5k. When I measure the eyelets with the multimeter, I still get 7.21k.

    I suppose I could try replacing the leads?
     
  4. chris m.

    chris m. Poster Extraordinaire

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    By deduction, if you have a good connection at the end of the lead then the only possible explanation for the delta is something going on with one of the leads. Maybe measure resistance between the end of the lead and where it connects to the pickup? It should be very close to zero but maybe if you wiggle the lead while measuring you will see resistance spike up. Then you'll know which of the two leads is messed up, since it's very unlikely to be both.

    One other possibility is it could be the way the lead is connected to the pickup. If that connection somehow got partially disconnected that would cause increased resistance. But it should either be a lead wire or the lead wire connection to the pickup.
     
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  5. theprofessor

    theprofessor Friend of Leo's

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    Great, thanks! I'll do that in just a bit and report back here.
     
  6. Danb541

    Danb541 Tele-Meister

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    how are the batteries in you ohm meter?
     
  7. theprofessor

    theprofessor Friend of Leo's

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    I think they're fine, since they measured every other pickup I have recently without any issue whatsoever.
     
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  8. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

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    Take a solder tool and fresh solder . . . touch the contacts where the leads are soldered to the pup.. add a touch of fresh solder, hold the solder tool there for about 5 seconds..

    now check those puppies..

    r
     
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  9. theprofessor

    theprofessor Friend of Leo's

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    Thanks so much, Ron. That worked! I was really flummoxed by this. Was there just a bad connection where the leads attach, and I drove some solder down there deeper into the connection?
     
  10. Rowdyman

    Rowdyman Tele-Meister

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    Are you sure you are not touching the leads, (with your fingers) when measuring at the ends of the wires?
    That could make you see funny 'readings'.

    Cheers, RM
     
  11. theprofessor

    theprofessor Friend of Leo's

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    Yes, I was using gator clips.
     
  12. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

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    yes. it has to do with the "technique" used when attaching the leads..

    The wire, at 42 AWG is simply too fine to strip the enamel from... so when the leads are soldered the heat is high enough to "burn" it away.... however, this being planet earth, known in the sentient universe as the place where Murphy's Law reigns supreme .. ( this is why we haven't been invaded by space aliens. they cannot factor in Murphy in the invasion strategy :p) anyway. sometimes the connection is not all that could be... and becomes intermittent over time.. or occasionally almost immediately out of the box... but reheating, applying new solder thus new flux, resolves it handily..

    rock on.. and don't worry about space aliens.. :D

    r
     
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  13. Tone Specific

    Tone Specific TDPRI Member Vendor Member

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    This is good advice to solve this type of issue. You can also use this technique on a pickup when the reading is zero. Before you assume a pickup is dead, it a good idea try to clean the gunk out of the solder joints with this technique. It’s also a good idea too hook up the pickup to a multimeter while performing this fix. That way you can watch the meter while applying new solder. This will prevent you from applying too much heat unnecessary heat to the pickup.
     
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  14. Rob DiStefano

    Rob DiStefano Doctor of Teleocity Vendor Member

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    sometimes the answer is too simple to see the forest for the trees. cold solder joints abound!
     
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  15. theprofessor

    theprofessor Friend of Leo's

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    Thanks very much, Ron! And as for space aliens not being able to factor in Murphy's law: isn't that one of the main plot twists of H.G. Wells's War of the Worlds? -- they did not account for human bacteria and virus? That's come to mind a lot lately.
     
  16. theprofessor

    theprofessor Friend of Leo's

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    Yes! And let it be known -- I have never, ever had this problem with one of your pickups (and I've had a lot of them)! Only with a Fender pickup.
     
  17. Tone Specific

    Tone Specific TDPRI Member Vendor Member

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    We always use some very fine sand paper to remove the coating from the wire at the point where the wire will touch the eyelets. This is more art than science unless you have x-ray vision. It’s easier to see on formvar vs enamel and becomes increasingly difficult with 43 awg vs 42 awg due to wire thickness.

    This use of sandpaper along with testing the pickup in various conditions before sending to the customer almost eliminates this issue of bad solder joints for us but very occasionally one gets past us. Sometimes it takes a year or more for it to occur.

    It’s doubtful that the large manufacturers do as much and the variety of testing that we do. The point is that if you are reading this & you have a drawer with dead pickups in it, you should try the fix ronkirn suggested. There is a very good chance a few of those pickups might actually be In working order with a little TLC.
     
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  18. theprofessor

    theprofessor Friend of Leo's

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    So while we're on the topic of wire... what accounts for the difference in color between the copper wire on this Cavalier Wolf neck pickup (42 AWG) and this Fender CS 51 Nocaster neck pickup (43 AWG). I'm assuming it's more that simply the gauge. Is the wire on the CS 51 Nocaster coated with something that could have contributed to the problems I was having?

    [By the way, another thing I've noticed that is also visible in the following photos is how thin the flatwork is on the Fender, in comparison to the flatwork on the Cavalier]

    Cavalier Wolf (marked "FL," but it's a Wolf)
    IMG_2157.JPG

    Fender CS 51 Nocaster (it's a really dark color, like burgundy wine or something)
    IMG_2158.JPG
     
    Last edited: Mar 26, 2020 at 10:18 AM
  19. Tone Specific

    Tone Specific TDPRI Member Vendor Member

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    The Fender is using Plain Enamel wire. The other pickup is using with Poly or Formvar, most likely poly if the wire is indeed 42awg. Poly coating melts away easier than Plain Enamel other than that Plain Enamel is just fine.
     
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  20. theprofessor

    theprofessor Friend of Leo's

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    Are those different types of wire supposed to encourage different "sonic properties," according to the aficionados?
     
    Last edited: Mar 26, 2020 at 10:40 AM
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