Convert to push-pull split coil leaving all original PCB and connectors

Discussion in 'Luthier's Corner' started by Marcello, Nov 30, 2019 at 5:00 PM.

  1. Marcello

    Marcello New Member

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    I would share my experience to convert a Gibson SG 2014 modifying the original PCB with installation of 2 brand new CTS 500K push-pull pots.
    In this way the original circuit board is mantained and all the components too. No need to cut/replace the pickup connectors, because not really needed.
    Many people say that pcb and connectors sucks but I think it's not the truth.
    Anyway, mantaining in place all original components we will ever have the choice to change them later.
    Note that in order to remove the pcb from the guitar we don't need to remove the toggle switch.
    After removing the pcb, the conversion is made by these steps:
    1. unsolder and remove the 2 tone pots from pcb (this could result difficult without a desoldering iron or a desolder pump);
    2. drill two small holes near pickup connectors;
    3. thru these new holes, solder two thin yellow wires in the pcb each connected to the 'square' terminals of pickup connector plug (for each pickup);
    4. bend upwards the 3 terminals of each pot and cut the eyelets leaving maximum lenght in order to allow enough soldering lenght (see picture);
    5. solder the switch terminals of any pot: 'C1' to ground and '1' to new installed yellow wire.;
    6. mount the 2 new CTS pots and solder them to pcb. Pay attention to neck/bridge position.
    I used 2 tricks: first - to solder I keep the new pot in place pcb helping by screw it temporarily with his nut, second - I used a bare wire to connect C1 terminal to ground.
    The sequence is shown in pictures.
    The choice of the 2 CTS lies in the same footprint of genuine ones. I preferred to shorten the 2 small tab-pins of the pot because they keep height in the low cavity of SG to avoid of raise up too much the pot and lift the back cover plate. In this way is perfect.
    Let me know what you think. 20191126_193947.jpg 20191126_194439.jpg 20191126_214630.jpg 20191127_182833.jpg 20191127_185256.jpg 20191127_193636.jpg 20191127_202249.jpg 20191127_213826.jpg 20191127_225022.jpg 20191127_225046.jpg
     
    Last edited: Nov 30, 2019 at 5:11 PM
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  2. Huntroll

    Huntroll Active Member

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    Marcello, that is some super-nice work !

    On mine I just installed a PCB from an SG HP-II and modified the control cover.

    cover-1.jpg

    Have you considered having each pull-up switch activating the common pair of pickup coils in each pickup by utilizing the unused switch contacts?

    For instance have one switch assembly shorting both white/red pairs when activated and the other switch assembly shorting the green/black pairs when the switch is lifted ?
     
    Last edited: Dec 2, 2019 at 12:48 AM
  3. Marcello

    Marcello New Member

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    Very fine and well done job too.
    Yes I think. But in this starting project I was approaching a simplest way. As my pcb is standard, the internal wiring don't has a separate coil circuit because the end/start are connected internally at the pcb. So the 'square' contact (end-coil1) is wired together the next one(start-coil2). To separate end-coil1 from start-coil2 a cut in the pcb is needed.
     
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  4. Huntroll

    Huntroll Active Member

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    * * * PICKUP CABLING WIRING COLORS * * *

    * * * NECK PICKUP * * *

    PIN - 1 = WHITE .

    PIN - 2 = GREEN .

    PIN - 3 = RED - PCB PRINT CONNECTS TO OUTPUT CKT .

    PIN - 4 = BLACK - PCB PRINT CONNECTS TO GROUND .

    PIN - 5 = SHIELD - PCB PRINT CONNECTS TO GROUND .


    * * * BRIDGE PICKUP * * *

    PIN - 1 = RED .

    PIN - 2 = BLACK .

    PIN - 3 = WHITE - PCB PRINT CONNECTS TO OUTPUT CKT .

    PIN - 4 = GREEN - PCB PRINT CONNECTS TO GROUND .

    PIN - 5 = SHIELD - PCB PRINT CONNECTS TO GROUND .
     
    Last edited: Dec 3, 2019 at 1:18 AM
  5. Marcello

    Marcello New Member

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    Of course not all SG wirings are equal. A very detailed picture in post "57 Classic Pickups Phase Issue" shows the current wiring in SG pcb from 2014.
    In these cases, the coils are wind in reverse phase, so the Neck has normal wiring, the Bridge has reverse-phase wiring.

    Assuming SQUARE pole = 1 the wiring is:

    PIN 1 = RED - BRIDGE / WHITE - NECK

    PIN 2 = BLACK - BRIDGE / GREEN - NECK

    PIN 3 = WHITE - BRIDGE / RED - NECK

    PIN 4 = GREEN - BRIDGE / BLACK - NECK

    PIN 5 = SHIELD

    PIN 1 & 2 TOGETHER; PIN 4 & 5 TOGETHER
    2014-2020_WIRING.png
     
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  6. Marcello

    Marcello New Member

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    BTW your wiring is really useful. Gibson makes always changes in wiring and maybe a library could be useful to collect all diagrams. THX!
     
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  7. Huntroll

    Huntroll Active Member

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    Notice in the drawing, the PICKUPS magnetic polarity order.

    Starting at the NECK, the drawing shows :

    NORTH
    SOUTH

    then -

    NORTH
    SOUTH

    * * * THAT IS FOR LES PAULS ! * * *

    * * * SG'S ARE DIFFERENT ! * * *

    * * * SG'S ARE AS FOLLOWS :

    Starting at the NECK, they are :

    NORTH
    SOUTH

    then -

    SOUTH
    NORTH

    IN MY EXPERIENCE, STOCK SG PICKUPS TOGETHER, IN A TOTALLY STOCK SG, SOUND SLIGHTLY LOWER IN VOLUME WHEN COMPARED TO A TOTALLY STOCK LES PAUL.

    NOT "OUT OF PHASE", JUST SLIGHTLY LOWER IN VOLUME, (WHEN COMBINED).
     
    Last edited: Dec 4, 2019 at 1:42 AM
  8. Marcello

    Marcello New Member

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    I haven"t said that pups are out of phase. Absolutely not. Indeed some 57 Classic, some Burstbucker and 4-wire Gibson genuine aftermarket ones, out of the box have connectors wired out of phase (see the diagram & the linked post), so if you don't have the right pcb the resulting sound will be out of phase.
    Some people cut connectors for this reason.
    My SG has the wiring of bridge with non standard colors but Gibson pcb compensates the inversion.
    Many people experienced this issue buying a couple of new 57 classic and attempting to install it into the guitar. The colors are swapped in factory so the sound results phase reversed. The issue is solved easily refering to the diagram above, cutting connectors and changing the position of wires, by a point-to-point new wiring. Finally, no matter if would be used connectors or not, the wires inversion causes the issue anyway and have to be fixed.
    The output volume is another problem and is not joined with phase issues
     
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