Why did Mesa criss-cross leads of the 50/50 OTs?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Humble Texan Fan, Aug 23, 2018.

  1. Humble Texan Fan

    Humble Texan Fan Member

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    In an effort to revitalise my Mesa Fifty Fifty it's going to receive a new set of filter caps, bias-pot and OTs with more iron to them. As seen in the photo below the bundles of wires from each OT are cable-tied separately. Then for the 8 ohm outs the orange wires cross over to the yellow wire of the opposite OT.

    Any particular reason Mesa would do this, you think? Those 2 x 4 ohm outs below (mostly obscured by the yellow and orange) are a single green without any interference from the opposite transformer.
    [​IMG]
     
  2. Jeff Gehring

    Jeff Gehring Silver Supporting Member

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    Per the schematic of the 50/50, there is NO interconnection between channels. The OT secondary taps are wired to two 4 ohm jacks, an 8 ohm jack and then a negative feedback connection back to it's phase inverter cathode stack.
     
  3. Humble Texan Fan

    Humble Texan Fan Member

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    Cheers mate. Yes, I didn't find any evidence of such wiring on the schematic either. And it would appear as if all versions have this.

    That orange wire could be somehow connected to the feedback circuit then. There seems to be some red wires running from the presence controls towards the OTs, which I have yet to remove, and I suppose that these could somehow be interconnected.
     

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