Texas Special Bridge reading 240k

Discussion in 'Pickup Forum' started by newfrontier, Feb 28, 2021.

  1. newfrontier

    newfrontier New Member!

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    The bridge PU sounded terrible these past few months. Both the neck & mid PU sound great and read in the 6.2-6.5k range. The Bridge is reading around 240k. Very similar to the issue from this video.

    The PU has been pulled and I have to consider steps for a repair before a replacement.

    Does anyone have any idea what would cause a pickup to do this? Connections? Coils? Poles? Magnetic charge?
     
  2. PCollen

    PCollen Senior Stratmaster Silver Member

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    Did you measure the pickup before or after you removed it ? Assuming you are measuring correctly and your meter is functioning correctly, its either an external or internal wiring issue. If external you can touch up the external wire solder connections on the pickup, and verify that the internal wiring that connects to those solder connections is good. Other than that remove the cover and try and see any damage, and report back.
     
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  3. archetype

    archetype Senior Stratmaster

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    Likely it's an internal break and there's enough capacitance that's it's still measuring as if it has continuity through the coil.

    Try @PCollen's post, first.

    If that stuff doesn't work, you can try to resurrect the pickup, or sell it as non-working and get some cash for it.

    Resurrecting it is potentially destuctive. You can desolder the outermost end of the coil wire and start unwinding the coil. If there's a break near the outside of the coil, just discard the extra wire and solder the end of the coil wire back to the grommet. If the end is near the outside, and you don't need to remove too much wire, then success. At worst, the break is so far in that you end up with too few winds to sound good.

    In any case, there's not much to lose by trying. It sounds like crap, now, and won't get better on its own.
     
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  4. newfrontier

    newfrontier New Member!

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    @PCollen All 3 pickups were measured 3 ways prior to removal from the pickguard, beginning at the the pots-to-switch and moving my way to the pickup lugs themselves. Neck and mid measurements at PU lugs were exactly were the needed to be. Bridge registered ".239 ohms" after switching to Megaohms setting, but prior to that only registered "O.L".

    Upon closer inspection, I noticed the coil is frayed upwards near the lug and a potential break in the winding.

    Images were taken after "lightly" re-heating the solder to see if any of those electrons would fall into submission. No luck. This is strangest thing I've had to troubleshoot. ts_bridge1.jpg

    ts_bridge2.jpg
     
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  5. newfrontier

    newfrontier New Member!

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    @archetype True. Fixing it is a mute issue. I want to find the cause of this failure so I can sleep at night, lol.
     
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  6. PCollen

    PCollen Senior Stratmaster Silver Member

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    It's not recommended to measure an electrical component (in this case a pickup) in-circuit...at least one "leg" of the component should be isolated to avoid the possibility of the influence of other components. Even a bad or marginal solder joint, switch contact, or frayed wire can throw the measurement off. Regarding your meter readings, if you set the range too low the multimeter display will typically show 1 , OL, or some other indication that it is overloaded or out of range. This won't hurt the multimeter, but you need to set the meter to a higher range, which you did by selecting Megohms.
     
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  7. archetype

    archetype Senior Stratmaster

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    Perhaps it's moot? If it were a mute issue, you wouldn't hear it. :D

    You definitely need to unsolder and lift either the positive or negative lead of the pickup to measure anything like the true resistance of the pickup.
     
  8. CB91710

    CB91710 No GAS shortage here Double Platinum Supporting Member

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    The "red" concerns me more than the "blue"

    It looks like something has snagged the winding itself at some point.
    The apparent break at the eyelet is not good, but doesn't necessarily indicate failure at that point.
    The coil is wrapped through that eyelet a couple of times to secure it before the leads are soldered in, as long as the leads are connected to the wire exiting the eyelet, it'll still work fine.

    I'd suspect that whatever broke the wraps through the eyelet is also what caused the apparent damage to the coil.

    What caused it? It's possible it was a factory defect that made contact will enough to work... broken ends of the wire held in place by the wax, resulting in a high capacitance connection, allowed sound to flow but not DC.
    As the bare ends of the broken wire oxidized, the capacitance changed and the low frequency cutoff increased to the point that it became a noticeable problem.
    The DCR would have been the same as the volume pot the whole time.

    ts_bridge1.jpg
     
  9. Mr. Lumbergh

    Mr. Lumbergh needs you to go ahead and come in on Sunday, too.

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    The good thing about seeing the break on the surface like this is that you should be able to unwind one or two wraps and resolder it to the eyelet to repair the pickup.
     
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  10. newfrontier

    newfrontier New Member!

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    lol
     
  11. newfrontier

    newfrontier New Member!

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    You are correct regarding the DCR. All pickups have consistent readings, whether it's through the switch/tone pot or directly on the pickup.

    Removing that much wire down the location of potential issue will def cause the pickups to lose inductance. Giving it a shot though.

    "broken ends of the wire held in place by the wax, resulting in a high capacitance connection, allowed sound to flow but not DC."

    I believe this is what they call a "Zombie pickup". There's current flowing, which means there's a connection, so I wonder if it has something to do with the magnets themselves.
     
  12. CB91710

    CB91710 No GAS shortage here Double Platinum Supporting Member

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    High frequency will flow through the gap.
    Refer to Jvin's comment in the Josefina thread about adding a capacitor in series with a pickup to get the "vintage" tone... the capacitor in series with the pickup effectively cancels the parallel capacitance caused by adjacent windings on machine-wound pickups.
    Not that I agree with his idea of doing that to get a "vintage" tone, but he is correct in the effect it will have on the circuit.

    On the comment on removing the wire....
    IF that white connection is to the outer wrap, then you can de-solder the lead from the eyelet, suck out the solder, and by unwrapping only a single turn get enough wire to feed and loop back through the eyelet and reconnect to the lead.
    Loss of a single wrap out of thousands will not impact the inductance or DCR enough to make an audible difference... nor even a measurable difference.

    However, if the white is connected to the coil start and that wire dives under the coil, then the pickup is toast and in need of a rewind.

    The magnets MAY have something to do with the weak tone, but they have nothing to do with the DCR.
    You are measuring ~250k, which is the volume pot.
    Switch the pickup selector to the neck position, and again measure the bridge pickup, and it will read open.

    The magnets are a long shot... if someone left those pickups in a box, the magnets would naturally align, and they'd be fine. If someone forced two of the pickups together against the magnetic force and then secured them with tape, that is magnetically "shorting" them and they will weaken... but your problem is with only one of the three, and the probability of that happening is so remote.... it would be more likely that the magnets would be damaged (particularly the neck pickup) by someone using a trigger-style soldering gun on the selector switch and pots.
    Soldering guns make very effective degaussing coils.
     
  13. hamerfan

    hamerfan Strat-Talker

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    If the measuring is done right and you see the value of the volume pot, you should have a short in the pickup or pickup hookup wires. The least would be my guess.
     
  14. CB91710

    CB91710 No GAS shortage here Double Platinum Supporting Member

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    Open.

    The pickup is in parallel with the volume pot, so a shorted coil will drop to "0", open coil will show the volume pot in position 1, or the middle pickup in position 2.
    Positions 2 and 4 should be similar, likewise, positions 1, 3, and 5 should be similar.
     
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  15. jvin248

    jvin248 Senior Stratmaster

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    Remove the solder at the white wire eyelet.
    Unwrap the outer layers of the coil wire until you are well past the 'loose'/'frayed' bit you notice on the coil, cut, scrape the coating off the end of the bobbin wire to expose the copper, thread the eyelet several times, resolder.
    Check continuity of the pickup itself (outside of the circuit).

    There is a mile of wire on a pickup bobbin. Unwinding a hundred feet of it is no problem.
    I had one 70s pickup I had to unwind 20% to get beyond the coil break -- and it sounded better than its twin because it had less internal capacitance with only slightly less output. Don't get worried about how much you remove.

    Just be careful and not break off the start end of the coil or you are rewinding the whole thing.

    .
     
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  16. fenderkev

    fenderkev Most Honored Senior Member

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    A simple and easy fix that everyone here seems to have ignored. [​IMG]
     
  17. CB91710

    CB91710 No GAS shortage here Double Platinum Supporting Member

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    ;)
    vvvvvvvvvv