Troubleshooting humming after pickup install

Discussion in 'Tele-Technical' started by AmnesiacBear, Sep 6, 2019.

  1. AmnesiacBear

    AmnesiacBear TDPRI Member

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    Hey all,

    I've got a ~2010 MIM Tele. I came back to playing electric after years of hardly touching it, and decided to try installing some fresh pups, despite my lack of electronics experience. The stock ones were noisy and didn't sound great to my (admittedly inexperienced) ears, and I wanted a project to tinker with. So I grabbed a Fender Vintage Noiseless tele set and went to work.

    Since I've installed them, I'm loving the tone except for one critical issue: there's a pretty loud hum on the bridge pickup only, even clean without distortion/OD. The humming gets louder when I touch any string or the bridge plate, and the humming basically stops completely when I touch any of the control knobs or the control plate itself.

    I'm a complete beginner when it comes to electronics, so I'm not sure how to figure out where I went wrong here. Is it possible the potentiometer is bad? Maybe I didn't solder something cleanly enough? I wanted to see if maybe these symptoms sounded familiar to anyone here before I went in and started ripping things out, resoldering, or replacing anything.

    Anyone have any ideas?

    Thanks
     
  2. Matthias

    Matthias Tele-Afflicted

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    General point first... Noiseless pickups still have some hum... And they don’t remove the hum from the rest of the wiring.

    To get the most from noiseless pickups, shield all your cavities with conductive aluminium or copper tape (with a conductive adhesive), and ensure those cavities are all grounded. If you already have shielding paint in there, which not all MiM models have but some do, check it’s all grounded and doing the tape doesn’t hurt if you want to try it. It can have a minimal effect on tone due to capacitance, but I’ve shielded several and not noticed anything. You can even put shielding on the pickguard and make sure that connects to the rest.

    That aside, it sounds like your bridge plate might not be grounded. When you touch the strings, you’re acting like an aerial, boosting what the strings are picking up. If things are grounded properly, hum should go away when you touch any metal. Which model do you have?
     
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  3. beninma

    beninma Friend of Leo's Silver Supporter

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    You've got a broken/miswired/badly soldered ground somewhere.

    I can't say exactly what it is.. It's the kind of thing you have to look through the wiring to figure out.

    Touching anything and having the hum get louder is a pretty good signal of a bad connection somewhere.

    It's very possible something broke while you were installing the pickups, it could be one of the original factory wires broke free.. I would be looking at wires soldered to the back of the volume pot. I had that happen.. I opened up the control plate and one of the solder joints was bad and me opening the guitar and then closing it back up was all it took for it to break.

    If the cavities are painted flat black & have wire leads screwed into them that connect to the harness you already have shielding and shouldn't need to worry about that in combination with noiseless pickups. I don't know what year they started doing that in MIM Teles, mine is a 2016 and has the shielding.

    There is a lot of room to reduce wiring harness induced hum just by doing a really nice job wiring it. I redid mine and used < 1/2 the wire of the stock harness and the hum level went down a lot.
     
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  4. Telecentric

    Telecentric Tele-Meister

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    First thing I would do is a continuity check from the bridge to control plate. If greater than 2-3 ohms, you have a problem with the bridge ground wire. It sounds to me like this was an issue before you changed the pickups.
     
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  5. kbold

    kbold Tele-Holic Silver Supporter

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    ^^ That.
     
  6. eallen

    eallen Tele-Afflicted

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    That +2

    Eric
     
  7. AmnesiacBear

    AmnesiacBear TDPRI Member

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    Hey thanks for the input everyone, I checked under the bridge. Although continuity check passed between the ground solder point on the bridge pickup and the output jack, there's no continuity between the bridge itself and the output jack. I'm in over my head here, so I don't know if that's supposed to be that way.

    There is a floating solder tag that originally connected a screw in the body to the stock bridge pickup, which I desoldered at the tag and soldered the new bridge pickup ground wire:


    IMG_20190911_134715950.jpg
    [​IMG]

    I did a pretty sloppy job, but continuity seems to be there. Should I maybe try cutting out the floating solder tag and instead solder directly to the tag under the screw? I'm pretty green with the multimeter too so I'm not sure what other tests I can be doing other than simple continuity.
     
  8. IronSchef

    IronSchef Tele-Holic Platinum Supporter

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    there should be a ground wire under the bridgeplate - this wire is typically routed through to the control cavity, where it is grounded to either the back of the pots or to the cavity shielding. I am guessing that wire either got lost during the bridge pickup swap, or its just not making good contact w/ the plate (the end of the wire is stripped off, and the bare wire sits pressed between the bridgeplate and the body)
     
  9. AmnesiacBear

    AmnesiacBear TDPRI Member

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    There's a wire that's supposed to be connected to the actual bridgeplate, and also a separate ground wire that comes from the pickup? Or am I misunderstanding?
     
  10. EsquireBoy

    EsquireBoy Tele-Meister

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    Yes that’s it: your pickup is grounded from one of its two wires, and the bridge have to be grounded: it can be through a separate wire (under the bridge that contacts the latter and is soldered to the back of one pot); it can also be grounded through the pickup baseplate if you have a jumper between the pickup ground wire and the pickup baseplate itself.
     
  11. Telecentric

    Telecentric Tele-Meister

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    From another thread here

    images.jpg

    Solder the other end of the wire to a ground point on a pot.
     
  12. AmnesiacBear

    AmnesiacBear TDPRI Member

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    This might be a dumb question, but how do I attach a wire to the bridge to ground it? I don't see any screws that I could attach a solder tag to. The pickup is screwed into the bridge, so maybe I could attach it to those screw somehow? Those are only small nubs sticking out on the underside of the bridge, though
     
  13. Telecentric

    Telecentric Tele-Meister

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    Just screw the bridge down on top of the wire (without insulation). The wood will compress, and the bridge will hold it in place. That's all there is to it.

    You could use the pickup mounting screws with a ring terminal, but it needs to be compressed between the spring or tubing and the bottom of the bridge plate. Most are just sandwiched between the body and bridge though.
     
  14. AmnesiacBear

    AmnesiacBear TDPRI Member

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    So it turns out that floating solder ring that I wired the pickup to was probably originally for grounding the bridge, and I didn't notice when I took the old pickups out. I screwed the bridge through the ring so it sandwiches between the underside of the bridge and the rubber pickup tube. Boom, bridge is grounded, hum is gone.

    Thanks everyone for the input, I'm very happy to be able to use both my pickups without causing me and everyone else a headache!
     
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