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Electronics oddity

Discussion in 'Pickups & Electronics [BG]' started by hibeam, Jan 4, 2003.

  1. hibeam


    Oct 16, 2002
    For the entire time I've had my beat up Yamaha, the electronics have always been a problem. Its a 9 volt active EMG situation, but the problem is actually the jack- it cuts out. I took out the jack (which was jammed, so I destroyed it on the way out) With the intention of replacing it, but I soon realized that the only spare jack I had was a stereo one. I figured I could probably use it as a mono anyway, so after trial and error I found the right contacts to solder. The strange part is, I have to ground one of the contacts to the sleave of the jack, and I can only do this when it is going through my finger. If I solder a wire attaching it to the sleave, no dice. I figure it needs some resistance or something, which is why it works through my finger, but why should this happen in the first place? Does it have to do with the fact that the jack is stereo and cannot be used as mono?

    The other odd thing was that I pulled a jack out of guitar and hooked it up and it didn't work. Somebody help me!
  2. I think you need a stereo jack for EMG pups... At least that's what I have in mine.
    There are EMG wiring diagrams Here

  3. hibeam


    Oct 16, 2002
    Hows is the wiring to the jack?
  4. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Bettendorf, IA USA
    When you plug a mono cable into a stereo jack, the single sleeve of the mono plug creates a short across the stereo plug from the shorter contact arm (what would normally contact the ring on a stereo plug) to the ground.

    So, by wiring the ground from the battery to the regular ground and wiring the ring spade to the PU ground, you get a switch.

    Plugging in the cable closes the circuit by providing ground and thus you get juice to the PUs. Removing the cable breaks the circuit and keeps the battery from draining when not in use.

    Most all active basses work like this.

    The above diagrams represent this well, but look these photos that compare a mono and stereo jack.


    Left is a mono jack. The contact arm locks into the tip of a mono cable plug and the sleeve on the outside grounds against the body of the jack.

    Right is a stereo. In stereo use, the longer arm locks in the tip (left channel), the shorter touches intermediate ring (right channel) and the sleeve of the jack grounds as normal. As you can see, if a mono jack is plugged in, both the ring arm and and jack body will be in contact with the mono plug's sleeve. This is what creates the switch.

    Ground from the PU's goes on the shorter arm spade and ground from the battery goes on what would be the regular ground spade.

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