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Precision Bass Has No Output

Discussion in 'Pickups & Electronics [BG]' started by DiabolusInMusic, Apr 14, 2014.

  1. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    I recently shielded two basses. I was trying out conductive paint for shielding (and loved it.) The first bass was a Fender Standard Precision and the second bass I did was a Peavey Fury Precision. I did the exact same job to both. I am not that good with electronics, I just know shielding. Because of this, I did not take apart the electronics I just pulled it out as a harness and put it back as a harness. The Peavey came back together just fine but the Fender has zero output.

    I did the same work to both instruments. I just added shielding and grounded it. I also shielded the pickup covers and added a strip of copper tape under the bridge. I had to re-attach a pickup on the Fender but it snapped one wire at a time, so they were both soldered back to their correct spots.

    The wiring in the Fender all appears to be correct and the solder points all seem to be well done. The pots measure resistance as do the pickups. The pickups measure very different numbers though, one measures over 220 ohms and one is just over 5. Is that correct? That seems like quite the difference

    I really do not know what to check but I cannot imagine it can be terribly complicated aside from a pickup having failed. I am worried I might have somehow nicked a wire on a pickup. Possibly the shielding is touching the pickup? I am hoping talkkbass can provide me some help.

  2. Probable reason for no output? Either an "open" or a short. The fact that you measured different resistance on the pickup halves is suspect. Are you using your multy meter properly? 5 ohms is far too little resistance, almost a dead short. But even if half the pickup was shorted out, you should get output from the other half passed to your amp, and you should hear "something". I would carefully recheck the wiring. Be careful when reading a component while within a circuit. Isolate each component to get the true value.
    To start, I would retest each pickup half again. Making sure they are independent of the circuit while doing so...BTW, do you find the shielding matters?

    Ket us know.
  3. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    Not with a P Pickup you will get no output because they are in series and if you short or open one coil the pickup is dead. 5 ohms is way too low for pickup resistance should be 5k or more. Also if the pickup is wired into the tone/Vol Circuit that changes everything. You need to lift one lead of the pickup to get anywhere near accurate measurement because otherwise you are measuring through pots ect.
  4. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    The pickups were not in the circuit when I tested them for resistance. I individually removed each one and checked them. I kind of figured something was up with them to have such a dramatic difference in output. I am most definitely using my "multy" meter properly and it is a quality Fluke unit. I have gone over the wiring multiple times, all connections are smooth and shiny. I do not get anything as far as output, not even when I tap directly on the magnets. I know shielding matters as I do not play basses that hum when you do not touch them.

    5K or more? The neck only had 220ish and the bridge was only 5 ohms. I am guessing I probably nicked a wire on the pickups when cutting out the glue to remove the cover.
  5. I believe you are half right. Yes the P pickups are in series and yes if one were open, the pair would measure infinite resistance and no output, but if one were shorted, it would effectively act like a piece of wire and only the other pickups resistance could be measured and I would expect some output from the non-shorted pickup.. I dont think he "nicked" a wire, because if he did the pair
    would measure like an "open" (infinite resistance).
  6. Try this: take your pickup pair and temporarily and directly connect it to the tip and sleeve of your guitar cord, there by eliminating all other possibilities. Use some duct tape or other tape to hold the PU leads to the line cord tip and sleeve (or use alligator clips which you should have out by now anyway). Plug the other end of the line cord into your amp. Excite the pickups with a tuning fork or vibrating bass string if you can. If you get no sound, either the pickup is hosed, or your line cord or amp is at fault. Should be easy to diagnose this way.
  7. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    Something like this happened to me when I did copper foil shielding on one of my basses. I found that one of the wires at the output jack was touching the foil and grounding the signal. All I had to do was bend the contact a little so it didn't touch the foil.

    Since you didn't disconnect anything, I wonder if you are having the same problem.
  8. Crater


    Oct 12, 2011
    Dallas, TX area
    What bassamatic said...make sure none of your 'hot' terminals on either the pots or the output jack are touching the shielding foil.
  9. ex-tension


    Jun 11, 2009
    Probably that shielding is somehow shorting your pickups. 5ohm or 220ohm resistance is way too low for standart pickups. As the others mentioned, you should read like 5kohm resistance.
    Try to measure the pickup resistance again without the covers.
  10. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    The shielding in the covers does not touch the pickups. The covers were also not on when I measured resistance. The covers were glued on and I had to cut them off. I used an x-acto instead of a blade screwdriver and I believe I nicked a wire on the wraps. I am going to double check the wiring but I have already ordered new Fender Standard pickups, they are cheap and common.

    Thanks for the help though.
  11. ex-tension


    Jun 11, 2009
    If you nicked a wire from pickup wraps you should be reading open circuit not 5 or 220ohm. 5ohm means something is shorting.

    The problem is on the pickups, no need to check the wiring for this problem.