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HELP ME fix my wiring!

Discussion in 'Pickups & Electronics [BG]' started by BarkerBass, Oct 4, 2008.


  1. ok so yesterday i thought i'd try and rewire a project bass of mine from having a tone pot per pickup then a blend and master volume to having a volume and tone pot per pickup... sounds simple doesn't it? :eyebrow:

    well so far i've failed despite searching TB and google alot. the problem is that atm it's wired to have each pickup going into a tone pot then a volume and then onto the jack however both the volumes seem to be acting as master volumes, turning it down meerley changes the volume until silent rather than allowing blending like a jazz bass control system. What have I done wrong? please help me make this bass work properly again! :help: diagrams would be a huge help. some background info if it helps. the bass has a passive Pbass pickup in the middle and an EMG MMTW musicman at the bridge which runs into a coil switch before it's tone pot atm, the cavity is coated with copper foil... not sure if any of this is useful just thought i'd paint the whole picture for u guys. HELP! :help::crying:
     
  2. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    On your volumes, one pot lug is for ground. Leave that one alone, but reverse the other two connections, so each of your pickups is connected to its pot's center tap.

    Hope I haven't misunderstood the problem.
     
  3. Thanks that's worked great but my pbass pickup now hums like a single coil jazz does when it is not at equal volume with the musicman pickup, when this bass used to have a blend pot the pbass pickup was silent when solo'd but now it buzzes. This buzzing stops when I touch the coil tap switch or jack socket so I assume its earth hum, i just find it strange that the hum isnt there when the musicman pickup is dialed in. is there now something i may have wired wrong to create this hum? what can i do to stop it? :help:
     
  4. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    Well, I can't see the bass from here ;-) and so rather than keep guessing at what the problem might be, you might want to give this a look:

    http://www.stewmac.com/freeinfo/i-4000/

    My advice would be to make sure, at the outset, that your shielding is rock-solid, with no gaps, missing connections, pickguard and cavity connected when the pickguard is installed, pot bodies shielded, etc., all running to the jack body. I prefer running separate wires (braid, actually) but that's just because I've always been a little overkill on shielding.

    The diagrams in that article might make a light bulb come on at your end. Like I said, I can't see what you're doing. But anyway, I hope this helps solve your problem. I'll check back in a day or so.
     
  5. Thanks guys for the diagrams, i'm gonna go for a complete overhaul of the wiring, i think i may have melted a few wired with the soldering iron by accident since the cavity is quite crowded so i'm going to buy new wire today and rewire it all when i get home tonight, hopefully that should solve this hum issue :rolleyes:
     
  6. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    See if you can find some with Teflon insulation. Expensive, but tough as hell.

    Sometimes I've had to use thin, braid-shielded wire for the really tough ones. Shield goes to ground of course.

    Keep all wires as short as possible.

    Use hefty wire for grounds. Not automotive battery cable diameter of course, but something with a much larger diameter than your pickup wires for example. Even if you have to buy a $2 extension cord at Wal-Mart, cut the ends off, and pull the pair apart as a wire source. (Just make sure the solder penetrates the strands.)
     
  7. RyreInc

    RyreInc

    May 11, 2006
    Kalamazoo, MI
    I've never heard of this before; what is the advantage?
     
  8. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    It is good for the marginal cases. You can even use the pair. Or strip the insulation off several 1' lengths, enclose them in shrink wrap, cut to size. The instrument pickups and cavity are basically a slew of high-impedance junk just begging to behave like a radio antenna, or an antenna for man-made noise, that you are trying your best to convince not to behave as a radio antenna. That means good, solid, low-impedance grounds.

    Many basses are quiet with incredibly thin-wired ground runs inside the cavity. If it works, fine. (Save some money, who am I to argue.) But when battling noise, it helps to get extreme in your grounding methods. Or maybe I should say it doesn't hurt.

    Much of this has to do with peace of mind. If you're anal in your grounding and you still have noise, you can be confident the problem lies elsewhere because you've already knocked down the main culprit.

    Some background. I designed and built medical instrumentation in the early 1980s, where grounding was paramount. Built the first EKG front end that reflected true heart-valve action. All analog, dead flat to to 0.2 Hz, and carotid murmurs would shout their presence rather than hide unseen in the high-pass waveforms of the typical junk back then made by the famous names I won't mention here but are still in business. You had to have good grounds for it to work right -- tiny fractions of an ohm. We went broke buying thick braid but it paid off and I learned the hard way that grounding ≠ "running a wire." We tried that and it failed miserably. That's the reason I relate the story and probably why I am now a stickler for grounding.

    I would expect thick grounds to pay off less in a perfectly shielded cavity than they would in one that is incompletely shielded. Maybe no payoff at all. (If it can't get past the walls, it can't get into anything that's inside them so it shouldn't matter.) But... I can't see this guy's bass. I don't know what's in there, foil or paint or nothing or who knows what.

    Wait. Did I mention wide flexible copper strip?

    Never mind.
     

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