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Need to diagnose problem with my bass...

Discussion in 'Pickups & Electronics [BG]' started by mantekka, Sep 28, 2009.


  1. mantekka

    mantekka

    Nov 21, 2006
    Dublin, Ireland
    :confused:
    Right so I have a musicman stingray 5.
    All was fine with it until one day my strap detached and it dropped landing on the jack area. Bent the jack on the lead a bit.

    But since then (I'm pretty sure it didnt happen before that, but not 100%) its got this buzzing when plugged in.
    I've tried different amps and leads, and different environments and same problem each time. Sometimes it's worse than others.

    So, I turn on amp and there's a buzzing from it, kinda like interference. The buzzing gets louder when I touch the strings. So something to do with earthing? Also, the volume knob affects it so I can only really play with guitar volume up full, this is where the buzz is weakest.

    It's fine for gigs as the ambient noise masks the buzz. But when I'm trying to record it's a real pain.

    I brought to a guitar repair man, who's very popular, lots of people swear by him. But he couldn't find any problems and tried to tell me it was the amp or leads or interference from lights nearby or something. He checked the jack which appeared fine and said the pots were clean etc. Another guy did the same. So I'm kinda stumped now.

    Anybody experienced similar or have any ideas what the problem could be?
     
  2. XylemBassGuitar

    XylemBassGuitar Supporting Member Commercial User

    Aug 14, 2008
    Durango, CO
    Owner and Operator, Xylem Handmade Basses and Guitars
    Sounds like a tricky one...

    Assuming that the buzzing definitely started after the bass hit the floor on the jack, you might see if replacing the output jack itself fixes the problem...though I would be a little surprised if the other two repair guys didn't already do so.

    It does sound like a grounding/earthing issue to me, especially since you'd mentioned that the buzz occurs in several different environments and because the buzzing gets louder when you touch the strings (usually it is gets quieter as most guitar/bass manufacturers run a ground to the strings/bridge), but I can't be sure without seeing the instrument in person. Also keep in mind that most single coil pickups may buzz a little bit, even if the instrument is perfectly shielded.

    I would recommend taking a look at this article at StewMac on shielding:

    http://www.stewmac.com/freeinfo/Electronics/Shielding/i-3789.html

    You could try to do this yourself, or print it out and bring it to your repair guy and ask if they would be willing to try this out on your bass...if you follow all of the instructions, the StewMac guide does a pretty good job of at least reducing (if not eliminating) a lot of electronics buzz.
     
  3. Axtman

    Axtman Supporting Member

    Mar 3, 2008
    Seattle, Washington
    I agree about bending the output jack.
     
  4. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    I'm not sure what "Bent the jack on the lead a bit" means -- does that mean your cable bent too, or you took the jack out and saw that it was bent?

    So if the ground wire to the jack got disconnected, you'd lose output completely. And if you have to crank everything to get enough volume, that would (1) make all noise extra loud and annoying, and (2) might indicate that the ground wire to the output jack's lug is not fully connected any more. That could happen from a sharp jab at the jack while the cable is still in.

    Make sure you check your battery first -- weak battery will make the bass sound thin and noisy.

    If you're comfortable opening up the electronics, and can get some wire, we can talk you through a few ways to check for grounding problems (easiest if you can get a wire with alligator clips on both ends, but a simple wire will work too).

    Scary thing -- there's a preamp in there, so the jarring of the fall could have damaged the preamp.

    And then, of course, the techs could be right, the bass may be fine, and maybe it's just a "normal" issue you've had for a while that got a little worse for a day (maybe b/c the battery is losing juice).

    If you want to try to check out the grounding issue, post back with some of the other quick check up stuff and we'll go from there.

    Cheers!

    ltt
     
  5. That suggests the bridge grounding wire broke somehow. Maybe it was a tight run to the jack, and the fall moved the jack enough to break the wire.
    If you have a meter, insert a cable (with a metal sleeve) into the jack and test between the sleeve of the jack, and your bridge. There should be little or no resistance. If the meter shows 'open circuit,' you've found the problem.
    If you don't have a meter, I suggest you get one- they're handy and cheap these days.
     
  6. JonesKY

    JonesKY

    Sep 28, 2009
    1) I'd resolder the grounds, particularly along the string ground. I'd guess that after the 'drop' a hairline (or bigger) break occured that isn't necessarily visible. I found a ground wire that looked perfectly soldered yet slid easily out of joint. Resoldering/reheating the joint solved the problem.

    2) It could also be related to the lead connection on the pickup: small wires on minute connections.

    Hope these tips help. All the best!
     
  7. ReMmy

    ReMmy

    Jun 23, 2009
    Cd'A, ID
    man, sounds like there are a crapload of lousy "luthiers" around... maybe i should be a guitar tech.
     
  8. mantekka

    mantekka

    Nov 21, 2006
    Dublin, Ireland
    Hi guys, wow didn't realise there were replys until I checked today. Thanks for the help.
    Just to clarify a couple of things.
    • "Bent the jack on the lead a bit" meaning yes the cable bent. So no big deal there.
    • I have replaced batteries to make sure this wasn't the problem.
    I had a look at that link Xylem, wouldn't be confident tackling that myself, but I've saved the link & may bring a printout as you said.

    lethargytartare, you mentioned it may be a damaged preamp, this sounds like a possibility alright.

    I'm gonna try find somebody else with experience in this and maybe bring a printout of all the posts, would be a good checklist to work through.

    I opened her up and had a look inside. Although I don't have much of an idea whats going on and wouldn't be confident to try anything. All the solders look intact. The jack looks ok, not damaged or anything. Nothing obvious anyway. When I was taking off the metal plate around the jack input, I noticed there are a few little cracks on the surface of the bass. Like the enamel coating or whatever clear coating is slightly cracked. There's two close to the jack, and a slight but more under the jack plate cover. So it took a bit of impact around that area when dropped.

    Cheers for the help, its useful to have the opinions.
     

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