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NBD, but not a happy one!

Discussion in 'Basses [BG]' started by Mili, Feb 19, 2020.

  1. Mili


    Nov 14, 2015
    Hello Bass friends, this is my first NBD during 5 years activity here.
    I have a Yamaha BB424X which i love it so much. I want to put falts on my yammy for Funk and soul stuffs so i need a bright sounding bass for pick style and maybe slap, so I pulled the trigger on a used Squier VM 70's Jazz bass. Sorry for low quality pictures.
    It's in a very good condition, everything is working and no major dent or dings.
    But 2 things are annoying me and prevent the joy of New Bass.
    1-this bass is very dark sounding, I know new set of steel strings would help but to my ears it's very dark that i don't have much hope. when i open the tone pot max, it's like it's on 50%. My Yamaha in bridge position is much much brighter and Jazzier . I checked the wiring because I guessed the previous owner changed the pots to lower values like 100k but pots are original i think but i'm confused about wiring. I checked the seymour duncan jazz VVT schematic and it's different. Main confusion is about three black wires(one from bridge ground, one from bridge pu and one from neck pu which soldered to neck pu volume pot(1 in picture below). Also i'm confused about output jack. It's just a naked wire!!! (2 in picture below)

    2- previous owner put a piece of aluminum foil under the bridge!!! I know he did it for making a good electric contact with bridge but i think it's pretty unacceptable. Maybe just maybe the top end is dampening because of that!! You can see the edges of aluminum foil.
    What do you suggest? I appreciate any input. Thank you.
  2. fretlessbass

    fretlessbass Supporting Member

    Dec 3, 2010
    Tucson, AZ
    Try a set of Dunlop Marcus Miller super brights; I put them on a passive Reverend, and couldn't believe how much high end they added.
  3. eastcoasteddie

    eastcoasteddie Supporting Member

    !!! That bare wire is soldered to the Jack Tip !!!!!
    This is wrong and why you have audio problems.
    Compare that wiring with the Duncan Diagram.
    It looks like the cap is soldered to the center lug of the tone pot, compare to the diagram above.
    there should be a wire leading from the same connection as the red wire going to the Jack Tip where the bare wire is soldered.

    Also, there should be a ground wire from the Jack ground (the other lug on the jack) to the tone pot case.
    Correct these first and foremost!!!

    Those three black wires should be soldered one to each pot...
    Bridge ground to tone pot, bridge pickup to bridge pot, neck pickup to neck pot. It’s not technically wrong, but not really clean...

    each pot should be grounded to each other, also with soldered wire. I’m sure you can see it in the Duncan VVT diagram.

    you’d have to pull the bridge to see what the pervious owner did with the foil. It could be for trying to get a “better” connection, but it is not needed. I thought maybe he wanted to get the bridge up higher, too...maybe he was having string buzz issues and he didn’t know how to correct. How is the truss rod working? Is the neck straight? How is playability and strong height?
    Last edited: Feb 19, 2020
    gscroggin, tindrum, FenderB and 13 others like this.
  4. Hello Mili, I´m very "new" in his Forum, but I should suggest you as follows: the value of potentiometer for all Jazz Bass configuration are B250KOhm to the both Volumes and for the Tone Potentiometer is A250KOhm with a Capacitor o,47uF; the wiring must be isolated, not naked as is. I could see in the picture, that the connection on the Tone Volume is a little bit strange (!) - check the typical wiring diagram for JB @fender.com; the Aluminium foil, could be get out, because the surface os aluminium is, at most, a isolation media, it can not make a good contact to the bridge, better solution is to get out the bridge and check if the cooper wiring is there, if not, make it with 1,5cm without isolation, contact with the bridge surface.
  5. Mili


    Nov 14, 2015
    That's my confusion. In schematic there are only two wire from each pickup but in my case three. One white and two black.
    Yes, i did a complete setup and everything is fine now. The action is about 1/16" for A,D,G and 5/64" for E. If i go lower than 1/16, i will get fret buzz on last frets which I think is pretty normal for a low priced Bass.
    Last edited: Feb 19, 2020
    nbsipics likes this.
  6. JKos


    Oct 26, 2010
    Torrance, CA
    Biggest issue is the the tone pot to output is wired incorrectly. Fix that first. Move the bare wire that goes to the jack tip to where the red wire connects to the tone pot.

    That will make a HUGE difference.

    - John
    gscroggin, tindrum, MDBass and 3 others like this.
  7. Mili


    Nov 14, 2015
    Yes it's a mess. Is it cause of the dark sounding problem?
  8. Crater


    Oct 12, 2011
    Dallas, TX area

    Cut the bare wire off the output jack, and solder a new wire (as marked with a PURPLE line) to the other terminal. That will get your bass working normally.

    Do not worry about the other ground wires at this time. As long as your controls and output jack are tightened down to the control plate, they will get their grounding connection through the metal plate. J-basses have been wired like this at the Fender factory for decades.
    gscroggin, mikecd1, SirMjac28 and 8 others like this.
  9. Mili


    Nov 14, 2015
    I'm still wondering about those 3 excess black wires...
  10. JKos


    Oct 26, 2010
    Torrance, CA
    They are not excess. They are ground wires for the pickups and bridge. Some pickups have two "ground" wires. One for the coil and one for shielding (usually connected to the pole pieces, too).

    - John
    Last edited: Feb 19, 2020
    gscroggin, bdplaid, MDBass and 2 others like this.
  11. Mili


    Nov 14, 2015
    Two grounds for each pickup?!
  12. Mili


    Nov 14, 2015
    Should i replace it?
  13. JKos


    Oct 26, 2010
    Torrance, CA
    See above. I added why.

    Not for now. A tone pot will work in either configuration. Move that wire going to the output jack.

    - John
    Crater and Mili like this.
  14. Mili


    Nov 14, 2015
    Thank you very much.:thumbsup:
    Killed_by_Death likes this.
  15. joeeg33

    joeeg33 Supporting Member

    Sep 11, 2002
    Central New Jersey
    The extra ground wires are usually from the pickup cavities being painted with graphite paint. Then they put a screw with a wire and run it to ground. Which is usually a joke because the shielding job is very incomplete.
    Mili, Maxdusty and JKos like this.
  16. Replace those 250k Ohm pots with 500k Ohm, & put some Stainless strings on it, Voila! new-sounding bass
    Squittolo, boggus, Goatrope and 6 others like this.
  17. I would buy a new wiring harness. Tone Monster make a nice one with 500k pots and a Vol Blend Tone set up.
    I put 500k pots in my Jazz bass and it really opens up the top end. It's not to drastic but I feel it makes a difference and you can always dial out some treble if need be.
    That bass should be way brighter. Probably one of the brightest made.
  18. Maxdusty


    Mar 9, 2012
    Michigan USA

    I had a jazz bass that was "rewired" by the previous owner...and rewired incorrectly and haphazardly. It had grounding issues and the tone was terrible. Not only that, the pots used weren't what I wanted on it, the capacitor looked cheap. I ended up just replacing the entire wiring harness even though I'm comfortable with soldering and doing the work myself. It wasn't at all expensive and improved the quality of the bass dramatically.
    Mili likes this.
  19. 9Thumbs


    Jul 3, 2013
    Near Boston
    You can buy a wiring kit from Amazon(and others)that has the good CTS pots, a Switchcraft jack, and the right capacitor. Might as well start with the good stuff. I buy those kits for every bass I buy (always used)
  20. James Collins

    James Collins

    Mar 25, 2017
    Augusta, GA
    I second this answer.

    The tone pot is currently wired so that when it is in the 0 position, the signal goes to ground across the capacitor with a parallel connection across a 250k resistor to the output. In the 10 position, the connection goes across a 250k resistor and then parallel connections to the output and across the capacitor to ground.

    When you rewire that one connection in the 0 position, the signal will be parallel connections to output and across the capacitor to ground. When in the 10 position, it will be a parallel connection to output with a connection to ground across 250k resistance and the capacitor.

    I think the sound in the 0 position will be louder and maybe as a result brighter because it won't have to cross 250k of resistance to the output. The 10 position will definitely be brighter and louder.

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