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Bass signal decreases significantly after center detent on bass pot...?

Discussion in 'Pickups & Electronics [BG]' started by MattS, Sep 13, 2017.


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  1. MattS

    MattS

    Jan 17, 2011
    Cheshire, CT
    I have an Ibanez SR505 bass and the Bass pot is a B100k pot with a center detent/midpoint. For some reason, the whole signal, overall volume, lowers significantly after the detent/midpoint turning clockwise. Anyone know what could be causing that? It didn't always do that. Not sure if the pot needs to be replaced OR if it's something with the pre-amp. Any help would be greatly appreciated. Thank you!
     
  2. Torrente Cro

    Torrente Cro

    Sep 5, 2013
    Croatia
    Maybe pickups are out of fase. I had similar problem and when I switched wires on one pickup it was fine.
     
  3. matty1039

    matty1039

    Oct 26, 2015
    New Orleans
    I've got a Schecter that does that on the pickup blend knob. For some reason it usually means it is time to change the battery as it works fine with a fresh one.
     
  4. MattS

    MattS

    Jan 17, 2011
    Cheshire, CT
    This bass is eating batteries quicker than normal too, No it doesn't stay plugged in. I highly doubt that the pickups are out of phase, electronics have not been touched or modified as far as i know. Still looking for the culprit. What might cause the battery to die quicker?
    Thank you all!
     
  5. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    A constantly draining battery is a sign of improper wiring. The jack needs to be wired to turn the circuit on and off. If it is wired to "on" at all times, the battery never stops draining.
     
  6. 40Hz

    40Hz Supporting Member

    Go over to Ibanez's website and print out a copy of the wiring diagram for your bass. Ibanez publishes them for all their guiars and basses. Then carefully check every wire starting with the three on the output jack and make sure everything is the same as in the diagram. Odds are good the jack is just wired incorrectly. If it's not - and all your other connections are also wired correctly, then there's probably something wrong with either the jack (easy to replace) or the preamp itself.

    There might be a short somewhere and your battery is being grounded even though nothing is plugged in. If it is shorting, the battery and/or some part of the wiring should feel warm or even hot to the touch. A 9V puts out decent current for a battery. If it's shorting you'll be able to feel it.
     
    Last edited: Sep 14, 2017
  7. Your preamp ground is shorted to ring or if the pickups are active the ground on that is shorted to ring constantly powering it when it is unplugged.

    Use a continuity meter or continuity setting on an ohm meter and find your active electronics grounding from the pickups and the preamp, test from ground on preamp to ring on the input jack without the cable plugged in. Do the same for the pickups if they are active. If you hear the tone you need to do some rewiring and attach thay preamp/ pickup ground to shield.

    Also the pot could be bad, sometimes drop in level could be the pot having bad tracking capability.
     
  8. MattS

    MattS

    Jan 17, 2011
    Cheshire, CT
    So i used my multimeter, continuity setting so it makes a beep. No cable in input jack. I did hear a beep when I touched the black wires of the preamp circuit (ground) to the ring of input jack (longer lug on left of input jack shown in diagram)... Is that NOT supposed to beep at all when cable is NOT in the input? If Yes, could it be a bad input jack and that is causing the draining battery, therefore best to start with a new input jack?
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  9. According to the diagram, the ring is the center pin of the output jack.
     
  10. MattS

    MattS

    Jan 17, 2011
    Cheshire, CT
    It beeps in both spots; left and center lug of input jack
     
  11. You can use a trs cable plugged into the bass to figure out which is the ring versus shield and a continuity meter. Your preamp ground needs to move to the shield position that is why it is draining batteries all the time it is powered all the time
     

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