dead pickup?

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by jlo, Aug 8, 2008.

  1. jlo

    jlo Member

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    Hi guys. Its my first post so be kind to me:)

    I got a JV strat brand new a little over a year ago. For the past few months the bridge pickup has not been working. When it is selected, I hear a very faint, weak, barely audible sound. The neck, middle and neck/middle combinations all work fine. The guitar has never been gigged or been in a smoky environment.

    I just opened the cavity today (I know I should have done it long time ago) and checked all the wires and solder joints. Nothing is loose or disconnected. WTF? Took it to the local music store where a tech checked it out. He cleaned the switch but the pickup is still not working. He said the pickup is dead and that everything else is fine.

    Has this ever happened to anyone? I know some people have had to get a vintage pickup rewound but a relatively new guitar? If the pickup is indeed dead, what caused it?

    Thanks in advance for your expertise.
     
  2. Rosewood

    Rosewood Member

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    If the pickup has a break in the first few turns or a cold solder joint at the base plate you can repair it without rewinding. Resolder the connections at the pickup first and if that doesn't do it start dewinding to see if you can find a break in the first few turns. Other wise it's rewind time, it happens all the time.
     
  3. jlo

    jlo Member

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    Thanks for your help. Couple of questions:

    Will reheating the joint be enough or do I need to remove the old solder? I tried reheating both joints but it didn't do anything.

    If I need to unwind the wire, from which lead do I start and how many turns should I go before giving up?
     
  4. Rosewood

    Rosewood Member

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    Do you have an ohm meter to test the coil at the solder joints top make sure the coil is open? As far as unwrapping to find a break it would obviously have to be on the outside wrap since you can't reach the inside wrap. You take as many wraps off as needed but I wouldn't go more than the first layer, after that it's a rewind. It would be a good idea before you unwind any to make sure the pickup is actually open.
     
  5. wavey63

    wavey63 Member

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    There is info on the web on how to repair a pickup like this. Do a Google search and if I can find it I will post the link. Good luck!!
     
  6. jlo

    jlo Member

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    Sorry for my ignorance but can I use a multimeter with the pickup still wired to the guitar? I'm assuming if the bridge pickup is not selected then the circuit will not be complete and I can therefore test if the coil is open?

    Let me get this straight. Assuming the coil is open, would I proceed to remove the solder and unwind one end or both ends of the wire? If I unwind both ends and find the break, then does it matter which end goes back to the hot lead and which one goes to the ground?
     
  7. Rosewood

    Rosewood Member

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    You can only unwrap the outer lead, it's impossible to unwrap the inner (start), only the outer (finish). If you touch the probes to both solder joints you should get a reading of 6k or a little less with volume control on 10 or switched to another pickup.
     
  8. jlo

    jlo Member

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    The coil appears intact. Got a reading of about '5k' across the solder joints. Checked all the connections in the wiring with the multimeter. Don't know what the actual values should be but there doesn't appear to be a break and I had already reheated all the solder joints before I posted the first time.


    Heres a link with a paragraph 'why do vintage fender pickups die?' http://www.provide.net/~cfh/pickups.html Interesting reading but it doesn't help me find a fix

    Any other suggestions?
     
  9. walterw

    walterw Gold Supporting Member

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    if you're getting about 5kohms across the two solder points of the pickup, while the selector switch is switched away from that pickup (this is important) then the pickup is good, and your trouble lies elsewhere.
     
  10. jlo

    jlo Member

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    Yes, it reads 5K with the pickup NOT selected. The pickup is fine I guess. Any other suggestions for troubleshooting? Am I missing something or not doing something correctly?
     
  11. Structo

    Structo Member

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    The JV strat has the bridge pickup wired to the second tone control correct???

    What do you get when you are switch position 2 ( bridge + middle)?

    With it plugged into a live amp, take a small screw driver, switch it to #2 and tap on the middle pup and bridge pup.
    You should hear the tapping through the amp if the pup is working.

    Without seeing it, it's hard to diagnose.
    Check all the wires going to and from the second tone pot and the switch.
    A wire may be broken at the solder joint.
    The switch may be defective.
    The tone cap may be shorting to a ground, etc.
    There has to be something wrong in the wiring if you are getting a 5K reading on the pickup.
     
  12. jlo

    jlo Member

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    I think I overlooked something important. I tested both the neck and middle pickups separately with the pickup being tested NOT selected. They both read 6.61K and I get very consistent and accurate readings. When I test the bridge pickup, the readings jump all over the place but tend to read around 5.XX M. Is this possible? I kind of assumed that it read K but it reads in the order of magnitude of M! Something is definitely not right. Any suggestions with this new information?
     
  13. Rosewood

    Rosewood Member

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    Your reading seems to indicate an open coil. Another clue is the weak thin signal produced. 5k is low but would produce a good signal, 5m or anything close sounds like an open coil if you are measuring correctly.
     
  14. walterw

    walterw Gold Supporting Member

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    yup. you can hold a test lead in each hand and get a reading less than 5M. a bad solder joint at the lead would just give you "open" and would produce no sound at all, so a 5M pickup coil is likely broken internally.

    oh darn, now it's time to put something cool in there, like a fralin steel-pole 43 or a dimarzio virtual solo. :D
     
  15. jlo

    jlo Member

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    Thanks for everyone's help. The guitar might actually be still covered under warranty so I'm going to try to get the bridge pickup repaired or replaced.

    That being said, I'm probably going to replace the set in the (not so distant?) future. Of course I'm going to tell my fiancee that I had to get a new set of pickups because they broke :)
     

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