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Help - P Bass Pickup Died Over The Weekend

Discussion in 'Pickups & Electronics [BG]' started by Dminor7, Oct 12, 2017.


  1. Dminor7

    Dminor7

    Jun 17, 2016
    My bass stopped working, and I could use some help / advice.

    It's a late 90s "Crafted in Japan" P, with passive US Pickups.

    I get no signal out of the bass. All components test in spec, except the pickup. Pickup reads between 21kOhm and 22kOhm on the multimeter.

    1. What is wrong with the pickup?
    2. Can it be fixed?
    3. If it needs to be fixed, is it worth it?
    4. If I need a replacement, what do you suggest?

    (More details below)

    No obvious physical damage or anything like that. Bass spent the week at home. Played fine 7 days earlier. Had not plugged in during the week (quiet practice!), but when i plugged in at soundcheck - nothing. Stompbox tuner could not recognize a signal. Cranked amp all the way to no effect. Backup bass worked perfectly, so that narrowed things down.

    Under the 'guard, it's a .022 Cap. 250kOhm pots. cloth covered wiring.

    I have checked all other components in the bass with a multimeter. wiring is correct across everything. grounding is good.

    Help Please!
     
  2. Yep. Your p'up is kaput. If you liked the way it sounded, you could have it rewound. The only person that I know of that does rewinds is Lindy Fralin, but surely there must be others.

    As far as aftermarket replacements are concerned, you've got a ton of research and reading to do as there are a lot of good solid choices available.
     
    Rattman likes this.
  3. catalin gramada

    catalin gramada

    Dec 25, 2014
    Did you measured you pickup disconected ? You need to disconect the wires to pot to measure properly. So, disconect at least one wire from pot (white one, supposed black is allready conected to the shield) and do a measurement between white wire and shield. 2. check the return path continuity (meant "negative" path) between the point where pickup is soldered to shield and jack ground. Sometimes seen the signal return was made through the shield and not with separate dedicated wire. In this case you need to check the continuity of this path with all components properly fixed, specialy mechanical contacts to the ground, like jack for instance and/or even pots which can be related to the ground via the case. Everything depends how was mounted inside. You cannot burn a winding coil I.m sure you pickups are allright
     
    Last edited: Oct 12, 2017
    Rattman likes this.
  4. Dminor7

    Dminor7

    Jun 17, 2016
    c.g. - pickup was checked when disconnected from the pots. black wire was unsoldered, and both path continuity and resistance were checked. coil failure was my last guess, but that's what i'm left with right now.

    the extremely high resistance is a mystery. any idea what can cause it?

    and if the coil is OK as you suggest, and the pots are OK, wiring is OK, what else could be causing complete signal failure? losing the capacitor shouldn't kill the circuit entirely, right?
     
  5. catalin gramada

    catalin gramada

    Dec 25, 2014
    You recorded 20K with both, seried connected ? did you measured separate each coil to see if shows equal DC resistance? At least I.ll run two separate wire from pickups to jack with nothing connected in between. I bet you have a short somewhere but not in the coil. If you have a broke in a coil you don.t get DC reading. Anyhow 20k picked directly to the coil is uncommon. I can read 10.9 K on mine with both coils series connected and also 8.1K from a Squire P-pickups
     
    Last edited: Oct 12, 2017
  6. It's caused by having a break in the coil.
     
  7. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    @Dminor7 ....If you get 20K with the coils in series and isolated from the controls I suspect a high resistance solder joint at an eyelet on one of the bobbins where the coil wire is soldered to the pickup leads. Fixed many of those over the years.

    If the PU is not potted in epoxy and you can see the eyelets, first determine which pickup half is at fault by reading the resistance. The bad half will have much higher resistance than the one that works. Have a small tip, 15/20 watt soldering iron fully up to temperature with the tip clean and well tinned for quick heat transfer. Touch up the solder joints at both eyelets by adding just a taste of fresh solder. Have everything ready and take as little time as possible doing the touch up to avoid melting the plastic or over heating the small coil wire but make sure the old solder reflows. Too much heat will make the small coil wire brittle and may cause it to break at a later date. As previously mentioned, rosin core solder only.

    If the PU is potted in epoxy it's toast and can't be rewound.
    1.
     
    Last edited: Oct 13, 2017
    Snaxster likes this.
  8. dagrev

    dagrev Supporting Member

    Jun 21, 2006
    Kentucky
    If you need pickups I highly recommend Klein Pickups. Snaxster recommeded them when I was fixing up a ‘64 P. Some of the best advice I’ve received.
     
    SpiceMan68 likes this.
  9. Dminor7

    Dminor7

    Jun 17, 2016
    mech - i think you've nailed it. no epoxy, yes dots. when i gently slid the cloth back on one of the leads on the E/A half, the wire detached from the pickup. something was very wrong with that solder join. i'm going to take your soldering advice and see if i can't put it back together. thanks for the helpful picture.

    at that point, if that does not work, then i'm right with you, lineoman - physical break in the coil. completely a mystery as to why or how....

    dagrev - thanks for the tip. i will check those out. i thought pedals were bad... pickups are a whole new wormhole
     
    mech likes this.
  10. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    The coil wire is most likely intact.

    Be sure to have the lead well tinned before soldering. Put a small amount of solder on the eyelet and immediately solder the wire back. Have everything prepared and the lead in your hand as it needs to be for soldering. Quick as a bunny. :)
     
  11. Dminor7

    Dminor7

    Jun 17, 2016
    @mech - thanks again for the advice. looking forward to trying this repair. first time's a charm, right?
     
    mech and ctmullins like this.
  12. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    Another piece of advice I should have included....Do not try to clean any of the broken lead out of the eyelet. The lead does not have to go through the eyelet. Doing either is dangerous as the small coil wire could be broken. Solder the lead onto the top of the eyelet and do not let the lead move until the solder joint has solidified. If the lead moves it will crystallize the solder joint and you'll have to do it again.
     
  13. catalin gramada

    catalin gramada

    Dec 25, 2014
    yeah, sloppy soldering from technicians which really should know what they do it, Cold solder joints-that.s pain in the ass specialy in signal ground path where tiny amount of fraction of ohms residual resistance bring a lot of noise in circuit.But tens kilo..Geez..I wonder if enamel was properly removed from the wire end. All over remarks I have to add to use good quality StPb alloy, not crappy-eco lead free.
     
    Last edited: Oct 14, 2017
  14. Dminor7

    Dminor7

    Jun 17, 2016
    @mech , @catalin gramada - thanks for the advice. really helped out. good news: soldering went perfect. reattached with the lightest of touches. bad news: not a bit of difference in bass output.

    multimeter's in the office. one more check on monday to see if i can pinpoint the failure, but i think i am now in the market for a new pickup.

    current options: fender '62 CS, lollar overwound, geezers, and klein '62 epic series.
    open to advice, etc.
     
  15. Rattman

    Rattman Supporting Member

    Your enameled coil wire has broken. Time to replace that poor old thing. Sure, get it rewound if you like it that much, but that will take time. Order something nice that you've always secretly wanted to drop in that cavity.

    . .
     
    mech likes this.
  16. catalin gramada

    catalin gramada

    Dec 25, 2014
    This is something running over my understanding as I recognize I have not experience with electric guitar pickups. How the heck a pickup coil can be broked ? You need to run continuous 100V arround 10k winding coil to get over thermal dissipation supposed 42AWG is rated for 10mA arround. Also it have very good mechanical stability into a rigid shell and wax or laquer potted. So how is possible to broke a wire into the coil in this circumstances, please ?
     
    Last edited: Oct 14, 2017
  17. jallenbass

    jallenbass Supporting Member Commercial User

    May 17, 2005
    Bend, Oregon
    I've heard the Lollar standard wind, EMG GZR and Kleins. All excellent. Fender is too scooped for my tastes but I can understand how others may like it.
     
  18. Dminor7

    Dminor7

    Jun 17, 2016
    wish i knew. the bass is from the late 90s, but has only been mine for about a month. my best guess is that the damage happened before it arrived. what i know is that it was a P-only at birth, and someone changed it to a P/J set up. the previous owner put it back to the original state. damage might have happened when the extra pickup was added, or when it was removed.

    i can't say i was impressed with the electrical restoration - it arrived with a crossed-up connection between the volume and tone pots. but that was an easy fix.

    when i pull it out for the replacement, i could dissect the coil and see if there's any obvious, visible damage and then post some pictures.
     
  19. Dminor7

    Dminor7

    Jun 17, 2016
    @jallenbass - thanks for the tip. my amp has a pronounced mid-scoop already, so i think the fender is going to be out of the running. out of the remaining three, do you have any preferences? I'm looking for a tone that sits well in a live rock band setting through a 4x10. warm, punchy, with a growl when asked