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Thread: Blackfacing a Fender Dual Showman reverb

  1. #1
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    Blackfacing a Fender Dual Showman reverb

    HI Guys.
    Decided to blackface a SF dual showman reverb for a customer.
    Now I have done a couple of similar conversions, but never one with a Trem circuit such as this.
    My question. Where does the 2,2M for the trem "jump start" need to go?
    Does it go to the diode side to the 3k3 or to the pot side as in the original SF circuit diagram?
    I have attached the original SF circuit.
    Thank you!
    Attached Files Attached Files

  2. #2
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    Here is a photo. The white wire in question is connected to the point where the 3k3 and pot pin meet.
    Attached Thumbnails Attached Thumbnails img_6874.jpg  

  3. #3
    Senior Member potatofarmer's Avatar
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    Is it working? Leave it alone. Is it not working? Wire it up like the schematic.

    It's just a voltage reference to shut down the oscillator tube when the tremolo isn't wanted; doesn't have any effect on tone or "blackfaceness."
    Justin Thomas and Chuck H like this.

  4. #4
    g1
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    My understanding is that it is a 'jump start' to avoid delayed trem engagement rather than just a shut off.
    But I don't understand the question. If you are sticking with the stock trem & bias circuits, then it should be already wired correctly as per schematic. If you are changing things, you need to show them. You are keeping the 3K3 ?
    potatofarmer likes this.
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  5. #5
    g1
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    Comparing to the AA270, I would say go with whichever end is closer to -52V.
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  6. #6
    Supporting Member Randall's Avatar
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    I doubt it would make any real world difference one way or the other, but if it did I think the CBS "improvement" was for a reason.
    Justin Thomas likes this.
    It's weird, because it WAS working fine.....

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