Pickup wiring schematic and date of manufacture

Discussion in 'PTC - PRS Tech Center' started by Vertigo, Aug 24, 2016.

  1. Vertigo

    Vertigo New Member

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    I recently picked up a '92 Custom 24. It's beautiful but the neck pickup sounds terrible. I've already messed around with the height and don't believe that's the issue. If I tap the magnets, it's good and loud but I'm wondering if perhaps these weren't stock on this guitar and were maybe wired incorrectly.

    I pulled them yesterday and they're both Dragon pickups installed in the correct positions in the body. According to the wiring schematic for the 1991-1994 5-way switch, the wires are soldered to the correct terminals on the switch. The schematic only calls out wire colors, not "hot", "split" and "ground". I don't see any obvious shorts.

    First question: The the Dragons come on the 1992 C24? I ask because the soldering job is pretty sloppy.

    2nd question: I know that PRS didn't have identical wire colors for the bridge and neck pickups for the hot, split, ground wires. If these pickups weren't stock, my guess is that someone followed the schematic but in doing so didn't actually wire it correctly. Was PRS consistent in the bridge/neck/split wiring color inconsistency throughout the years?

    Thanks,

    Sean

    edit: I tested resistance across the wires

    B/W - 7.84
    B/R - 3.94
    B/Sheath - 0
    W/R - 3.93
    W/Sheath - 7.84
    R/Sheath - 3.94

    I assume that Black and the braided sheath are essentially ground, white is hot and red is the split.

    The hot wire had a few broken strands at the switch so I just pulled, trimmed and reattached it. Had to borrow my wife's reading glasses for that little job. Hopefully that was the problem.
     
    #1 Vertigo, Aug 24, 2016
    Last edited: Aug 24, 2016
  2. Vertigo

    Vertigo New Member

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    that wasn't it. still sounds like crap
     
  3. Johan Allard

    Johan Allard New Member

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    I have a custom 22 that came with Dragon II's and I wasn't a fan at all so decided to change them.

    I believe to get the position 2, 3, 4 wiring to work correctly, one of the pickups needs to have reverse polarity (that the stock pickups should have). Basically you need a north and a south coil together and normally on a two humbucker guitar you'll have south-north north-south (i.e the screw coil is south and slug coil north, or wise versa). You can easily check this with a compass by holding it on either side of the pickup.

    With position 2, 3 and 4 they use inner coils in series, outer parallel and outer series from memory. It's all just the screw coil or just the slug coil anyway. With normal humbuckers you end up with either just north coils or just south coils so it doesn't work properly. So on with a rotary selector you need pickups that are north-south north-south.

    I ended up ordering a set of Bareknuckle VHII and got them to make the neck pickup with reverse polarity so that it would work in this setup.

    But I since decided to scrap the rotary and added a normal 3 way switch instead. Much easier to use and you can use any pickups you want.
     
  4. Vertigo

    Vertigo New Member

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    The issue is that the neck pickup has reduced output and sounds like garbage. I recall from the '93 I owned that the middle positions have their own idiosyncrasies and I'm OK with that but I expect the neck to sound decent and it hums, has a low output and generally sounds terrible.

    My kids lost my compass so I'll have to get a new one to check but I did the screwdriver pull-off test and found that both coils of the bridge pickup send the needle to the right, as does the slug side of the neck pickup, but the screws send the needle in the opposite direction. Is that normal? Doesn't that mean that the pickup itself is wired wrong? Is it possible that someone flipped the magnet or that the windings on one coil are in the wrong direction? I'm out of my depth at this point.
     
  5. jeffgoobs

    jeffgoobs New Member

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    Those are not the stock pickups. Custom 24s came with the HFS/Vintage Bass combo. The Dragon pickups are voiced for a 22-fret guitar, especially the neck pickup. Dragon pickups (Is and IIs at different points) came stock in Custom 22s... not 24s.

    Where did you get it, and was it stated that the pickups were swapped out?
     
  6. Vertigo

    Vertigo New Member

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    Thanks Jeff. So they've been swapped. I can work with that but I'm still wondering why the induction test on the neck pickup sends the needle travelling in opposite directions from each coil.
     
  7. jeffgoobs

    jeffgoobs New Member

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    That's odd... I wonder if the wire was wound around the bobbin in the opposite direction than it's supposed to be (either intentionally or by accident), in-turn flipping the polarity.

    I can tell you that the reason the level is so much lower in your neck pickup is because in 22-fret guitars, the pickup is placed directly above the 24th-fret harmonic overtone location, which makes a much thicker, beefier tone. Ergo, they are wound a bit less to compensate for this phenomenon so as to reduce any boominess that might result from placement in this location.
     
  8. Vertigo

    Vertigo New Member

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    I fixed it.

    I called PRS this morning and the customer support person was unfortunately unable to help. Apparently they don't have detailed schematics from 1992 and he wasn't sure if the pickup was supposed to be out of phase or not (I suspect not) but asked me to call him back with whatever I found out.

    Figuring that I couldn't make it any worse, I pulled it out, split the coils and swapped the leads on the offending coil. I didn't think through it all and my hot/ground are now reversed (I soldered them back into the switch after testing induction) and anyhow, it sounds like it's supposed to now. All the hum is gone in the four positions that aren't just the bridge, it's got a great sound now and the neck pickup is sounding pretty smooth.

    BTW, I don't doubt that these were made for 22 fret guitars, but if there's a volume drop when switching to the neck, I can't hear it.

    Thanks for the info you provided. It helped me get going in the right direction.
     
    wardog likes this.

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