These electronics are a nightmare.

Discussion in 'Pickups & Electronics [BG]' started by K-Funk, Apr 18, 2012.

  1. K-Funk


    Sep 24, 2007
    Auburn Hills, MI
    About seven years ago, I picked up a Vester four-string fretless that was made sometime in the late 80's or early 90's. It worked for a few weeks before giving up the ghost completely. I took it to a music shop for repairs, but they only managed to make the problem worse in addition to losing my input jack plate.

    I don't really know where to begin. It's an active bass with P/J pickups and a 9v preamp. It has four knobs, but they've never worked correctly and I can't determine what does what. Both pickups work, and I'm fairly certain one of the pots is a blend control, which would possibly mean the other controls are volume, bass, and treble. The last time I tried putting a battery in it and testing things out, smoke started trickling out of the preamp cavity. I also heard a rumor that this bass kicks puppies and steals kids' lunch money.

    I'm pretty handy with a soldering tool, but I have no clue where to start when it comes to making this bass useable. Furthermore, I can't really afford to take it to another shop to get it restored to a playable state. I kind of feel like I'm asking how babies are made, but if anyone can point me in the right direction to diagnose and repair the problems myself, it'd be muchly appreciated.
  2. mmbongo

    mmbongo I have too many basses. Supporting Member

    Time to drop back and punt. Replace the preamp and possibly the pickups. Especially now that you've let the smoke out of the preamp.
  3. MopHarris


    Apr 15, 2012
    Personally I'd go and google up some wiring diagrams for it if you can find it, try going off that first. If not use something similar to it.
  4. K-Funk


    Sep 24, 2007
    Auburn Hills, MI
    Yeah, I'm quite sure I didn't leave enough smoke for future operations. I might just convert the whole shebang into a passive arrangement if I can. The problem is that it's a super obscure bass made by a Korean company that only lasted three years, so finding diagrams and schematics will be nigh impossible.
  5. DavC


    May 17, 2005
    Tallmadge , Ohio
    go passive ... with 4 knobs , i went went Vol/Tone/Vol/Tone .. no smoke from that ..!

    use an external preamp ... if needed ...
  6. Crater


    Oct 12, 2011
    Dallas, TX area
    Any chance of posting a clear, in focus picture of the bass' innards? Especially the preamp?

    Hey, with a P/J pickups you can always go back to passive setup and replace all the electronics. There's only a couple of ways to wire up a P/J pickup bass. And there's really no magic or voodoo in the preamps either, they are more alike than they are different. In addition to a "soldering tool" (LOL), you should buy or borrow a digital multi-meter, a.k.a. a volt-ohm meter; they are ESSENTIAL for any kind of electronic troubleshooting. They're not expensive, you can probably buy one at your local auto parts store for $10.
  7. K-Funk


    Sep 24, 2007
    Auburn Hills, MI
    Tool, iron, whatever. Also, I've already got a multimeter, so I'm set to go. I'll try to post a photo of the electronics cavity this afternoon.
  8. bassbenj


    Aug 11, 2009
    Start now. Begin by figuring out what knobs do if bass is actually working (after smoke that may not be the case!). If bass is working get a paper clip or small screwdriver to tap on pickups. Finding the volume control should be easy as it controls the volume! Usually there are two configurations one is vol/vol where there is a volume control for each pickup and the other (more common in active basses) is a volume and a blend. To find the blend control start with all knobs in center and volume up. tap on pickups both should make a sound. Now turn the knob you think is blend all the way one way and then all the way the other way while tapping on both pickups. In the extreme positions first one pickup should work and the other be silent and then in the other rotation the opposite pickup should work with the other silent.

    Another way to find a "blend control" is to look in the cavity. The "volume" pot will be a single pot while the "blend" will be a stacked dual pot running from a single shaft. There should be a wire going from the blend control to the preamp. At this point you can test the bass without a battery by running the input wire that was going to the preamp to the output jack (after taking off the output wire from the preamp. If that works as expected, (should give you a passive bass with volume and blend that work) then the next step will be to troubleshoot the battery wires and the preamp. Since there was smoke and new cheap preamp might be in order as a fix.