Sd Hot Rail Pickup Testing- Need Help Please

Discussion in 'Project Depot' started by bc rich, Sep 8, 2019.

  1. bc rich

    bc rich Well-Known Member Supporting Member

    Joined:
    Jun 4, 2012
    Messages:
    2,232
    Likes Received:
    1,847
    Trophy Points:
    113
    Scratching my head here, bought a used Seymour Duncan hotrails and and tested it on arrival.
    Open circuit on both coils , seperated the red & white wires and retest , nothing , only the ground wire which was connected to the rails .
    I have another SD hot rails and it tests out just fine. I get the same results with another meter.
    The seller then asks me to test it in a guitar so i hook it up to an amp , tap on rails and walla it works . Hold it close to guitar strings and both coils are sounding good .
    Test for continuity at the cable jack after getting sound - still nothing .
    Tried the 200k range as i have been fooled by pickups that were above 20k ohms - still nothing
    I am doing something dumb and need help understanding what the dumb is.

    The top one is a new SD rail , the bottom one is the problem child. I am not sure if it a real SD.

    Thank you in advance
    DSCN0412.JPG
    This is what i am seeing.
    DSCN0386.JPG
     
  2. mozz

    mozz Well-Known Member Supporting Member

    Joined:
    Jun 10, 2015
    Messages:
    2,359
    Likes Received:
    3,234
    Trophy Points:
    113
    Location:
    NEPA USA
    Pickups do work sometimes with a open wire, it acts as a capacitor. I would think it would sound like shit though. You are best off to post on the SD forum, they would know for sure if it's fake.
     
    bc rich likes this.
  3. Sinster

    Sinster Well-Known Member

    Joined:
    Aug 17, 2008
    Messages:
    2,090
    Likes Received:
    1,342
    Trophy Points:
    113
    Location:
    Massholechusetts
    By the looks of it you have a north/south in each probe. You want to test it with red/white connected and check from black to green.
     
    bc rich likes this.

  4. Mickey

    Mickey Gandalf the Intonationer

    Joined:
    Jun 8, 2007
    Messages:
    33,632
    Likes Received:
    21,483
    Trophy Points:
    113
    Location:
    Wausau, Florida
    One wire open gives you a 20dB loss, so depending on the circuit gain, you could still get some signal. Sorta. :)
     
    bc rich likes this.
  5. mozz

    mozz Well-Known Member Supporting Member

    Joined:
    Jun 10, 2015
    Messages:
    2,359
    Likes Received:
    3,234
    Trophy Points:
    113
    Location:
    NEPA USA
    Yeah, there was a story on Roy Buchanan's tele guitar. They tested it and there was no resistance , it was open but still worked.

    Only other thing i could think of would be to test each and every combination of wires, manufacturers do change things over time. It looks totally different, i'm guessing fake.
     
    dabbler and bc rich like this.
  6. bc rich

    bc rich Well-Known Member Supporting Member

    Joined:
    Jun 4, 2012
    Messages:
    2,232
    Likes Received:
    1,847
    Trophy Points:
    113
    You are right , i tried another test with a nine volt battery .
    Red & white to one terminal.
    Meter lead to the other terminal
    With the other meter lead i got 9 volts on green and then black. Basically reading the battery voltage via the windings . As the is no current flow there is no voltage drop from the windings .
    With the problem pickup i read .004volts , most likely from capacitance coupling as you suggested .
     
  7. bc rich

    bc rich Well-Known Member Supporting Member

    Joined:
    Jun 4, 2012
    Messages:
    2,232
    Likes Received:
    1,847
    Trophy Points:
    113
    The flash makes shadows of the wires in the pic .
    I have tested it every possble way . I even separated the white & red and tested again.

    Red & white to green would give one coil
    red & white to black would give the other coil, and to green and black would give you both coils in parallel .
     

Share This Page