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Jaco Bass has no output!

Discussion in 'Pickups & Electronics [BG]' started by DiabolusInMusic, Mar 14, 2013.


  1. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    So I have let this Jaco (Artist not CS) bass get neglected for the last month or so (I know it is a tragedy... don't ask). I popped it out to take some pictures for another TBer to see a shielded Jaco and when I plugged it in to rock it out I had no output. So I needed to open it anyways now to see what is going on.

    Everything appears to be wired correctly still and it doesn't appear as though any of the wires have lost their connection so I don't know where to start. I have an electrician that can help me but it might take him a few days to get some free time... I'd rather not wait, now that I look at this bass again I am dying to play it!

    I suppose a pot or pickup could have failed but I have never seen that in my day, I thought it took decades for them to fail. I have a good multi meter handy if I can check this out easy enough.

    This is the closest thing I could find to schematics, if anybody has any better schematics I would appreciate them but I think this is as good as it gets.

    Thanks in advance!
     
  2. Stone Soup

    Stone Soup

    Dec 3, 2012
    My best guess is the tip connection on the jack (long bent metal that touches the tip of the guitar cable) isn't making a connection. Are any of your pots loose?
     
  3. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    No, nothing lose at all. I tugged on all the wires and such as well. I'll go check the tip right now.

    EDIT: Tip fits perfectly into the jack, makes a great connection.
     
  4. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    I should add that I had it in it's case, back down, with my Carvin case generally on top. If that might have caused something to shift I don't know, but I don't think that had any negative effects.
     
  5. temmrich

    temmrich

    Jan 29, 2012
    Dayton, Ohio
    Have you tried testing it with the plate off and the wiring hanging out? I'm thinking that maybe something is touching the shielding when you put the plate back and that its causing a short.
     
  6. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Yeah, I was testing it with the plate off, no strings and the pickups are not even screwed down. The linked post has some pics of the shielding job but they are not the greatest.

    I was just tapping on the pickups to see if they put out noise and didn't get anything.
     
  7. talknbass bro

    talknbass bro

    Dec 4, 2011
    One of your solder joints may have gone bad, or you may have build up on your output jack. You clean the jack's connecting parts off with a pencil eraser, that will help to eliminate a bad connection at the output jack.
     
  8. Bass2daMix

    Bass2daMix

    Dec 11, 2009
    California
    You've tried with different cable?
     
  9. It could be sulking due to neglect?

    Davo
     
  10. Sounds like the jack is touching the shielding.
     
  11. Stone Soup

    Stone Soup

    Dec 3, 2012
    That was my next guess. :)
     
  12. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Ok, so I now have output. I had the control plate off and was just spinning the knobs and touching stuff to see what kind of reaction I got. The tone knob gave me a cracking sound and the bass came to life, like a piece of debris had come loose. I sprayed some deoxit in the pot but the pot still has more friction to it than the volume knobs. Although from the sounds of it, I am pretty sure the tone knob is working fine.

    The bridge pickup volume seems to work fine but the neck pickup/pot doesn't seem to do much. The bridge pickup is only audible with the amp absolutely cranked. Before anybody says it, I know that pickup should be off anyways and it usually is but I want it to respond properly.
     
  13. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Nobody? I am sure the neck pickup should have more juice to it, regardless of it being a Jaco signature.
     
  14. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I've burned out cheap pots by heating them up too much when soldering. It can be done.
     
  15. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Good to know Jimmy, although I should add I didn't actually add anything to the pots or wiring, just added shielding and wires to ground them. The control circuit is factory fresh (to my knowledge, I did buy used)

    I looked into how to test a pot, it involves me removing it from the circuit.

    Is this a symptom of a failing pot? I just want to know before I go through the hassle of removing a pot.

    I took the bass out last night to vocal practice and found when I turn up the amp I get a hum, like an interference hum, that doesn't go away when I touch the bridge/metal. It also does not get louder. It also makes a static electricity pop, which I know comes back to shielding as I have removed that from basses before.
     
  16. PlaysAJunker

    PlaysAJunker

    Feb 21, 2013
    I thought you meant it had no output plug and I had to check if it was April already. .
     
  17. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Ha, no it has the actual jack. Which is working.

    I still have minimal output from my neck pickup and a constant, quiet, hum. Hopefully I can get this looked at today with my electrician.

    Nobody? I am thinking I need a new thread for more answers.
     

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