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Input jack, jacked?

Discussion in 'Pickups & Electronics [BG]' started by Downunderwonder, Jan 26, 2014.

  1. Active bass, cutting in and out when the lead plug gets wiggled. It's not the lead.

    I opened the control cavity and the 3 way jack seems all well connected and getting a good grip on the plug, yet the plug is easy enough to micro wriggle as most jacks do, while appearing not to lose contact. What's really happening?
  2. Crater


    Oct 12, 2011
    Dallas, TX area
    If it's a 'barrel style' output jack...


    ...then it's worn out. No way to repair it, just have it replaced.
  3. john m

    john m Supporting Member

    Jan 15, 2006
    The 2 poles short together internally.

    Replace the jack.
  4. pfox14


    Dec 22, 2013
    Have you tried different cords? Maybe it's not the jack at all.
  5. john m

    john m Supporting Member

    Jan 15, 2006
    I think
  6. Groovin61


    Feb 25, 2013
    Detroit, MI
    Just had the same exact thing happen on an active P I have from the late 80's. Couldn't figure it out. Took it to a tech who replaced the jack and all is well.
  7. F#maj7 = chord

    Wire that transmits signal = cord
  8. ahc


    Jul 31, 2009
    No. Virginia
    And... It's an OUTPUT jack. :bag:
  9. john m

    john m Supporting Member

    Jan 15, 2006
    Spellin was my worstest subject in skool.

    I'm much better at cypherin-- be-in an injuneer.
  10. It's TRS, for activating the power on the electronics. Can you expand on how it can short?

    Come to think of it, the cutting out is sometimes accompanied by gank noise like a short, but then it's silent, would it not hum if it was shorted?
  11. Thanks for other replies, well, some of them.

    Yes, I swapped leads first.
  12. Not that kind, it's just a simple faceplate mounting one.
  13. pfox14


    Dec 22, 2013
    LMAO - good way to start a day
  14. Crater


    Oct 12, 2011
    Dallas, TX area
    In that case, you might be able to clean it. You can use some fine grit sandpaper or even a pencil eraser. Gently clean the jack's contacts where they contact the plug. Roll the sandpaper into a small cylinder to clean the inside (ground/earth) portion of jack. Also check that the tip contact is making firm contact with the plug; if it isn't, you can try bending the contact in a bit to increase the pressure.

    If all that fails, it's a straightforward job to replace the jack.
  15. So, opposite of shorting? I'm still struggling with identifying the mode of failure.

    The way it's dead silent after it goes out is a bit spooky. I originally thought it was a dead battery.
  16. JTE


    Mar 12, 2008
    Central Illinois, USA
    The T/R/S jack for active electronics works as a switch when you plug in a standard mono (T/S) plug. The tip of the plug connects to the tip connector of the jack, sending the signal to the amp. The barrel of the plug shorts the ring connector of the jack to the sleeve connector, which is ground. That's the switch that turns the battery on and off.

    So, if the jack ins't making good electrical connections at either the tip or the ring, it's either not going to send signal to the amp, or it will shut off the battery. Either way, you're likely to get no signal.

    BTW, the difference between calling the jack on your bass an "input" or and "output" is important for more than simply semantics. Understanding signal flow is critical to troubleshooting. So, knowing that the signal comes OUT of the bass and goes to the input helps you figure out what could be going wrong. Connections always need to be from an output to an input.

  17. john m

    john m Supporting Member

    Jan 15, 2006
    Internal failure could yield a short-- tip to ground.
    The input to the amp would then be shorted---
    that's how one of my old cords worked. You could unplug it from your instrument to switch axes without turning down you amplifier. A little button popped out when unplugged.
    Try it--- plug in your lead to the amp and short the tip to the sleeve--- you should get silence.
  18. if it's a simple faceplate mounted one, then you can access the contact pads and push them towards the centerline a bit... that will ensure better contact...

    barring that, replace the jack
  19. halfjackson


    Feb 19, 2010
    Boston, MA

    I just replaced a 20 year old barrel jack last week. It cost about $10, and was very easy to replace.
  20. It looks like all the contacts are well made. The prongs both get a significant stretch out when the plug goes in. I'll give them a little rough up and push them in some more to eliminate bad contact.

    Shorting tip to barrel on a guitar lead generally is to be avoided like the plague. That's the godawful pop you get pulling a lead out of an active channel, no way I'm doing that deliberately.

    The sound is either silent or a minor glitch when it goes out.

    Is it possible for the barrel to lose contact without corrosion? I haven't considered that at all.