New 5f8a build

Discussion in 'Shock Brother's DIY Amps' started by mgrossm, Sep 19, 2020.

  1. mgrossm

    mgrossm TDPRI Member

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    2 questions

    1) Im gonna sound like im in over my head here and maybe i am, but if someone can give give me directions regarding how to wire the power switch and fuse (i thought this would be the easiest part). Need help knowing where to place black common and 120 volt white pt wire ...same with white and black from power cord. Not using grounding switch.

    2. Regarding grounding scheme for preampi was thinking of running an 18 vauge bus wire on the eyelet board. If i did that, i would need to connect one end to the ground tip of only one of the jacks? Normal (hi) jack 1? Also could the same bus wire just be soldered on the belly of the pots?



     
  2. jmp81sc

    jmp81sc Tele-Meister

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    Hi mgrossm
    Welcome to Shockbros,

    Just follow this wiring of the 120 volt power supply shown below from Rob Robinette, this is for the 5F6a, which is similar to the 5f8a.

    It is accepted practice now to run a ground bus wire to the input jack, if you do this then you don't need to solder the wire at the back of the pots. This is also shown on the layout below.

    Good luck with your build
    john

    [​IMG]
     
  3. mgrossm

    mgrossm TDPRI Member

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    Still confused regarding this diagram...my PT has a white and black wire..black is com and white is 120v. In diagram the white neutral from power cord is wired to a black wire on the PT....which PT wire sould i connect my white neutral power cord wire to?
     
  4. tweedy_woodpecker

    tweedy_woodpecker Tele-Meister

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    The important thing is that you connect the hot wire from your power chord to the fuse and not the neutral.
    If your transformer (maybe you can post which transformer you have or the data sheet) only has one primary winding it does not really matter which side you connect to the power switch and which side you connect to the neutral of the power chord. This is why both wires in robrobs layout from the PT are black...
     
  5. mgrossm

    mgrossm TDPRI Member

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  6. tweedy_woodpecker

    tweedy_woodpecker Tele-Meister

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    The picture is a bit dark.

    Connect your hot power wire (usually black) to the fuse, connect the other side of the fuse to one side of the power switch with a short cable, the other side is connected to the black PT wire. Then connect the two white wires (neutral and PT wire for local wall voltage).

    So in case something goes wrong and the fuse hopefully blows, there is no voltage potential after the fuse...
     
  7. mgrossm

    mgrossm TDPRI Member

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    Ok...will update. Thank you
     
  8. mgrossm

    mgrossm TDPRI Member

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    Oops
     
    Last edited: Sep 20, 2020
  9. mgrossm

    mgrossm TDPRI Member

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    Whats the function of connecting the PT common wire (black to power switch) in this plan?
     
  10. mgrossm

    mgrossm TDPRI Member

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  11. dan40

    dan40 Tele-Afflicted

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    When the switch is energized it completes the circuit. Black wire from cord to fuse, from fuse to one side of switch. One of the PT wires will connect directly to the other lug on the switch. The other PT wire will connect directly to the white wire from your power cord.

    You may see different wiring schemes because different kits come with different types of switches. Some switches will switch both the hot and neutral wires and other switches will only switch the hot line.

    One last thing, don't think of the PT as having a common and hot wire. The primary coil of the PT is simply one long wire coiled up inside of the PT with a lead at each end. It does not matter which one you connect to the switch as either end of the primary coil is the same. Most PT's just use black wire for both.
     
  12. mgrossm

    mgrossm TDPRI Member

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    That makes sense now.
     
  13. mgrossm

    mgrossm TDPRI Member

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    today did pt, heaters , switches...drilled holes for eyelet board in chassis...next up finish what i can of sockets...add choke, move to jacks and pots then eyelet board
     
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