Lame humbucker from my 85 Explorer 425

Discussion in 'Pickups' started by 1Way, Dec 25, 2004.

  1. 1Way

    1Way Active Member

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    Here is the front side.

    [​IMG]
     
  2. 1Way

    1Way Active Member

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    Here's an overview of the control panel.
    [​IMG]
     
  3. 1Way

    1Way Active Member

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    Here's a close up of the volume pot top and the location where the pickups wires come from. Also notice that straggling wire coming out of the difficult located connection tab at the bottom near where the black wire enters the cavity.

    [​IMG]
     
  4. 1Way

    1Way Active Member

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    And here's a closeup angled shot trying to see the mess at the solder connections at the base of the volume control pot. Note the very straight and stretched out wire between the tone and volume pots.

    [​IMG]
     
  5. 1Way

    1Way Active Member

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    Heres another of the same kind of shot. I had to push the wires out of the way to try to get a shot down by the lower part of the volume pot.

    [​IMG]
     
  6. ess

    ess Guest

    might just need a good fettle, check the hum for continuity. run through all the connections. if its bad,, junk it and get a replacement pup.
     
  7. 1Way

    1Way Active Member

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    Well this is better than suggesting that I buy a Kay SG copy. :shock: :?

    So, I don't know what fettle means. And how do I go about checking continuity. I have the multimeter, it has ohms, DC and AC Volts. and a thing called hFE. I think that might have something to do with testing certain diodes or PC chips, not sure though.

    It's a 20A max, and the ohms go from 200 to 2k, 20k to all the way up to 20m. It also has a little music note symbol, I think that is to show something like maybe continuity. It works, tested it on my pen.
     
  8. 1Way

    1Way Active Member

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    My volume pot looks like it's a prime candidate for troubleshooting, doing that alone might rectify things since there seems to be a short between two wires that I assume should not be connected.

    Volume pot mess
    Sorry the pics were not better, but there are three posts sticking out of the volume pot. There are also some connections on top of the pot that go through a black plastic upper housing. Same with the tone pot, only without the plastic housing. But on the volume pot, the first (nearest) post clearly has only one wire connected and it is going to the three separate on/off switches. The middle post and the far one is where the problem seems to be. All the pickup wires come with a braided outer lead and a separate shielded internal stranded wire lead. There is a wire that tightly stretches from the tone pot over to the volume pot and it is doubled over very sharply for about a 1/4" apparently to allow the outer lead to be soldered to the one post, and the internal lead to be soldered to the other post. However, it does not at all look clean, in fact, it looks like the far post may have both leads on it, perhaps both are soldered to it, not sure.

    control central mess
    It's a very poor job by whoever connected up the controls. The internal leads have only like 6 or so strands of wire per wire, and on the middle pickup switch, there are only 3 strands connecting it, now there are only 2 after taking the photos. Plus with several of the solders the strands are not neatly twisted together, instead they are frayed apart. There is some solder burn marks on the protective plastic for the wire going to the input/output jack, and the wire jumper between the volume and the tone control is way too short, its tight and has zero margin for error correction. Plus there's that lone cutoff strand of wire just sticking out of the far post on the volume control.

    Pickup wiring options
    So, perhaps there are more than one problem with the setup. The volume pot seems like a wreck, and maybe the pickup is wired in parallel instead of series and/or wired out of phase instead of in phase. My experience tell me that it's wired like the last entry, parallel and out of phase, both the tone and volume is diminished.

    I'm still waiting to know what to do to check out the pickup wiring. I don't see the colored wires coming out of the pickup, instead I see a wire braided wire with an additional inner lead hidden inside. But I haven't taken the pickup apart yet, only lifted it for an external viewing.

    CharlieB? Anyone?
     
  9. CharlieB

    CharlieB Active Member

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    SHow me a picture of the front of the guitar so I know what the layout and parts are.
     
  10. 1Way

    1Way Active Member

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    I did, it's the first pic...
     
  11. 1Way

    1Way Active Member

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    The second pic shows the rear of the guitar by the outer plastic shroud around the cable jack, which is to the left. The main dysfunction I see is that
    • The solders and connections are very poorly done
    • One connection (the middle tab) on the volume pot looks like it may have accidentally two leads connected instead of just one. The wire is bent to allow the farther outer tab to be connected to the outer shielding of the wire lead, and the inner wire is apparently supposed to connect to the middle tab, BUT, it looks like some of the outer shielding may be stuck on there as well, perhaps by accident, very sloppy, very hard to see even with the naked eye.
    • The jumper wire between the tone and volume is stretched "tight", thus that may be why the middle solder connection to the volume pot is messed up, because he didn't leave room to do it right.[/list:u] Secondly, I didn't find out much about the pickup yet, I would need to uncover the tape around the pickup to see the color of the wires that are otherwise covered up.

      I believe I will let a guitar repair shop deal with the wiring rework, I would do it but I don't have experience with such wires and solder. Unless you can talk me through that, I'm game to buying a soldering iron and some extra wire, but need pointers for which wire to get, etc.

      So what about the pickup, should I remove it and open it up? I don't have any replacement tape, do I need that?
     
  12. CharlieB

    CharlieB Active Member

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    Missed it.

    Go to

    www.gibson.com

    find their customer service email addy and give them a try for an original schematic/layout... what you have is non-traditional
     
  13. 1Way

    1Way Active Member

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    Been there, tried that...
     
  14. 1Way

    1Way Active Member

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    Do we need a wiring schematic? I could make one, it's all there. I'll make a diagram ASAP.

    The main difference with this nonstandard setup, other than being a single tone and volume control, is the three separate on off switches, and they are all separate and so it's somewhat easier to understand the logic for them, very straight forward arrangement overall.

    The issue seems to be only with one of the three volume pot posts, the middle one. Seems like you would simply reconnect them and just see if keeping things separate would help thing or not. It shouldn't ruin anything if it's not wired right, should it? I heavily suspect that it's not probably wired and it still works, just doesn't sound so great. Also, if you get a replacement pot, wouldn't that pot tell you what each terminal tab is for, or no?

    Gigson practically seemed surprised to learn that they made my guitar... They have no shcems, no ads, no specs, no nothing.
     
  15. 1Way

    1Way Active Member

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    Ok, here it is. The three protrusions on the pots are located at the bottom of the units. The top of the tone control is metal and thus common. The top of the volume pot is black plastic and likely the two spots are not common.

    First the wireless layout.

    [​IMG]

    This is without the pickup wire leads, only local stuff plus the two black plastic shielded wires, one from the 1/4" jack and the other, well I don't yet know exactly where it comes from.

    [​IMG]

    Now it's just the pickup wires included. The wheat colored blobs by the connectors represent solder locations so as to better clarify where connections are made.

    Some silver wires stop and black wires continue, that is the outer braided wires and the inner wires continue as a separate lead.

    [​IMG]

    And now it is all the wires together. This complexity is why I posted the two prior posts with less wires per illustration.

    Of special concern is the volume control middle position. It might have some of the outer shroud lead onto that connection, not sure, but I don't think it should be together like that as all the other outer leads group together and are always kept separate from the internal leads.

    [​IMG]

    I hope this helps...
    :wink:
     
  16. 1Way

    1Way Active Member

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    Oh, I forgot to mention that the mysterious single wire cut off soon after the volume pot's furthest tab, seems to be the end of the wire that goes from the top of the volume pot too that very tab. So that issue need not be suspect as a problem.
     
  17. 1Way

    1Way Active Member

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    I'm posting on Gibson's website, although I'm not sure I will find help there. Here's the link. Click here

    I had called up Gibson's customer service and they simply had no info on the guitar, other than letting me know that they used to make that guitar, and in what year they made it. Although the year did not match the website's claim of it being made over 2 years, and the fact that my serial number proved that it was made in a different year than the one he gave me. (chuckles) He did not know what pickups it had, no wiring diagrams, owner's manuals, nothing. I guess the early 80's were truly hard times for Gibson.

    Maybe an internet forum will provide better info. (???)
     
  18. ess

    ess Guest

    took me a while to figure out the problem 1way,. after many trial runs, i managed to come up with the solution.

    [​IMG]
     
  19. CharlieB

    CharlieB Active Member

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    Looks good to me.
     
  20. Sgmaniac

    Sgmaniac Guest

    43 different pickup combinations, cool! 8)
     

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