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Help with RobRob’s Classic 5E3 Schematic

Discussion in 'Amp Tech Center' started by Lancer X, Jan 23, 2021.

  1. Lancer X

    Lancer X TDPRI Member

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    Hi all. I’m building a Weber 5E3 kit and am using @robrob ’s Classic 5E3 schematic. There’s something I don’t understand on the diagram:

    There is a gray line between pins 8 and 3 of Valve 1. Does that mean there should be a jumper wire between those pins?

    V2 doesn’t show the gray line, and the jumper wire for pins 4 and 5 on both was shown in green. The only other gray lines are traces/grounds. Just double checking so I don’t blow anything up. :D
     
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  2. Jon Snell

    Jon Snell Tele-Holic

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    Yes, that means the two cathodes are connected to a common bias point. Screenshot 2021-01-23 at 18.30.07.png
     
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  3. dan40

    dan40 Friend of Leo's

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    Yep...as Jon mentioned above, v1 is a "shared cathode" arrangement and both halves of the triode are biased from the same 820r resistor.
     
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  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    This is the way the lovely ladies at Fender prepped the sockets back in the day. V1 has pin3 and pin8 bent across the middle to reduce wire. Pins 4&5 are twisted together so an additional bit of wire is not needed.
    LLC 5E3 tube socket.jpg
     
  5. Lancer X

    Lancer X TDPRI Member

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    Ooo, great tip. Received it too late for this build, but will do this for my next one!

    (Hmm, I wonder if Fender did something similar between the input jack sets too? I created a jumper with a piece of solid wire.)
     
  6. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    Well here is a pix of an original 5E3 courtesy tdpri member keithb7.

    Keithb7_5E3_Deluxe_Input_Jacks.jpg

    I notice they positioned them so it is easy to clean the jack switches.;)
     
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