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Passive wiring, volume will not go to zero

Discussion in 'Pickups & Electronics [BG]' started by Sean Baumann, Jul 6, 2003.


  1. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    I thought I was almost finished with my warmoth project, but it turns out that I have something wrong with the wiring. I'm using the following wiring diagram

    http://www.seymourduncan.com/website/support/schematics/p-j_bass.html

    However, I'm using sadowsky p/j pickups and a dual 500k concentric pot for the volumes. This is my first electronics project (basically), so I'm not wise on how to trouble shoot with a multimeter (although I do have one). I did a pretty messy job, but it doesn't look like anything is cross connected, and it is wired as show in the diagram. I've been soldering all of the ground connections to the back of the concentric pot.

    Anybody have any ideas of what to check or what would cause this? The volume does turn down correctly, it just never goes completely off. The bass is not strung yet, I'm testing by tapping on the pole pieces with a hex key. You help is much appreciated! thanks.
     
  2. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    you are missing a ground wire to the output jack. I can't remember which one, but look around for it.

    I had the same problem with my bass when Installed my EMG pickups.
     
  3. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    I have the connect to the ground, but it may be a cold solder joint. I did have a very hard time soldering the wires to the back of the volume pot. Any tricks for this?

    Could it be doing this because it is not yet strung, and it needs the strings for a proper ground?
     
  4. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    I also lack the skill/patience to solder onto the back on pots, so that's one of the reasons why I bought EMG, they have the pots already soldered and included with the pickups.

    What kind of solder are you using? that could make a big difference Is it a rosin base?

    THat doesn't help you however. I sounds like you have done most of the work, is there a local music store you can go to and have them give it a look?

    Mark
     
  5. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    I think that I am using rosin core. Is that ok to use?

    I'd rather leech off of the talkbass community for knowledge than go to the local shop. They charge way too much for this type of stuff.

    I was able to pull the ground connection off of the pot with my hands, so the connection was not good. I'll have to get some more solder today and try again. I'll make sure to file all of the crap off the back of the pot before I try and solder to it again. There are just so many connections I need to make to the pot that it is a major pain. When I get one connected, the heat pops off another. I have 2 pickups, 1 volume (the other volume is daisy chained to the other), 1 tone, 1 control cavity, and 1 bridge connection to solder to the pot.
     
  6. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    Rosin core should be fine, that's what I've had some luck with.
    At least you see why the local music store charges so much, this stuff can can be a pain.

    It sounds like if you just keep at it, you'll get the problem solved. if you have to make two connections to the same pots, you might try making them on opposite sides of the pot, like the 3 o'clock and the 9 o'clock position. might help that popping off problem.

    you might try the Luthier's corner for repair related question, you might get more experienced people answering than me.

    this thread is mildly helpful click here

    Mark
     
  7. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    thanks for your help!

    Actually I have 5 connections to make to the bottom of the pot, that's what is making it difficult. I'll try again tonight. So, the strings shouldn't make a difference w/ the volume problem, right? The bridge is a good enough ground by itself?
     
  8. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    The bridge should be fine. I think even without the bridge disconnected the volume knob should go down to zero. we are talking about two different issues here.

    wow! 5 connections! that's a wreck waiting to happen. can you merge some of those wires before you solder them to the pot?
     
  9. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    Now I'm confused. Yeah, actually it is 7, I must have miscounted before, connections that need to somehow get to ground (it is actually six, but I merged the two volumes to one ground connection). So, the connections are as follows: P, J, Tone, Volumes, Output, Shielding, and Bridge.

    I figured I should be soldering all of these to the common ground point, which in my case was supposed to be the back of the volume pot. What should I do with all of these connections?

    I was assuming before that the volume not going off problem was due to back grounding of the output jack. That ground connection is run from the output jack to the back of the volume pot at the moment. I'm guessing that the connection was bad because I was able to pull the ground connection for the volumes off the back of the pot with my fingers and not much effort. Am I making any sense?
     
  10. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    there's something I am missing. you should never have 7 connections to the same pot. I don't think I have ever seen more than 2.
    Can you take a picture and post it? Grounds can be daisy chained together, like christmas tree lights. you don't have to connect them all into one pot.

    Mark
     
  11. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    Sure, I'll do the picture tonight (hopefully). It's pretty messy in there, so I'll have to clean some stuff up so it is apparent what is actually connected to what.

    Well, where should I connect all the grounds to?
     
  12. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    I'll open up the back of my PJ fretless and try to draw a simple diagram showing how it is all routed back there.

    Mark
     
  13. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    That would be awesome! thanks.

    Regards,
    Sean
     
  14. tuBass

    tuBass

    Dec 14, 2002
    Mesquite, Texas
    well, I tried to take a picture of the cavity, and it turned out terrible. Basically, it's like I said. There is one or two grounds per pot, with the grounds linked together by means of the little legs that of each pot.
    You know who you should PM? there is a guy named Notduane who is known as the wiring Czar around here. He is a lot better about explaining these thing than I am, and even has a website set up with some wiring diagrams already on it. Look him up, he's a great guy. It's not that I don't want to help yuo, it's just I don't think I could do a good job explaining so you would understand it.

    Mark
    here is a plan off the EMG site. This is real close, but emg does not ground the bridge. there are instuctions on this page on what to do if you want to ground the bridge.
    EMG site
    [​IMG]
     
  15. Killdar

    Killdar

    Dec 16, 2002
    Portland Maine
    that would be funny if the pot was just stuck and just didn't turn all the way. ;)
     
  16. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    I think I fixed it. Thanks for the help! It was the ground connections to the back of the pot. I moved alot of the connections, filed the back of the pots, and tinned everything before I soldered. I think it is working just fine now.
     
  17. tip fo soldering onto pots:- get a sticky label, hole punch a hole in it and stick it on the back of the pup with the hole in the centre of the pot, sowhen solderin the conection the solder will stick to the pot and not the paper.

    also using flux will help the solder to flow, and a solder sucker useful to remove old solder
     
  18. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    I'd suggest soldering all five wires to one wire, then solder the single wire to the pot. The key to soldering to the casing is to get the casing hot enough to flow solder. First tin the case by getting a small spot of solder to flow. Once you've done that, then solder the wire to the spot. Be careful, though ... if you get the case too hot, it could damage the pot.

    Also, rosin core is the correct solder to use in electronics. Never use acid core.
     
  19. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    Thanks guys, that's great advice!!
     
  20. Sean Baumann

    Sean Baumann Supporting Member

    Apr 6, 2000
    Livin' in the USA
    Doh. Troubles return. Now I get some buzzing unless I touch a knob. I'm not sure that the tone knob is working 100% either. Ideas?