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Polytone V (early) schematic

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  • Polytone V (early) schematic

    I know that Polytone schematics are notorious to find - the same ones always seem to pop up
    I have an early (1970's) Polytone V (2 x 10) that needs work - I think the reverb driver circuit is bad
    It looks like it is basically 2 channels and that it is both model preamps listed as "Brute" series preamp 1-3. and 2-4 together
    The problem is that the component numbering doesn't match up.
    It has a long circuit board with both channels on it.
    Is there a specific #V schematic and a board layout diagram
    Just knowing which IC is what would help.
    Thanks
    Michael

  • #2
    Here is a schematic for a V1B preamp. ICs are not labeled. Can you post photos of the board? Component side and foil side.

    Polytone V1B Reverb Preamp Schematic.pdf

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    • #3
      Sorry about the delay in responding but we moved
      I've attached pictures of the board - top & bottom
      You can see that there is a lot of unpopulated real estate. One end looks like a typical Mini-Brute while the other is More like the ones with distortion and reverb.
      The ICs are replacement RC4739 upgrades/adapted chips - 8-pin chips on a 14-pin adapter
      The V1B schematic is different in that it doesn't have the distortion circuit and it does have tremolo, which the V apparently didn't
      I replaced some capacitors
      Right now something isn't right with the preamp as it is making odd noises, it might be the reverb drivers as the original transistors are no longer around and the subs have a different pin-out
      There seems to be a fair number of Polytone V's out there, but I can't find a dedicated schematic anywhere
      Thanks
      Michael

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      • #4
        I can draw the schematic if you can take a few more photos with the pcb out of the chassis. I need to see all parts of the board.
        I might need to know where some of the wires from the Molex connectors go, though probably it will be obvious from pcb side,

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        • #5
          I'll try to get better shots with the back off, the under board photos show pretty much everything
          This is an early Polytone V with 2 x 10" speakers and the "velvet" covering.
          I wonder if, given the "universal" look of the board if this was originally used in an earlier model that had tremolo/harmonic/etc. mounted in the center of the board.
          Michael

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