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    Tubes4hifi VTA70 v12-ccs driver board HELP!

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    charlief64

    Posts : 13
    Join date : 2012-12-21

    Tubes4hifi VTA70 v12-ccs driver board HELP!

    Post by charlief64 on Sat Feb 02, 2013 6:28 pm

    Bewitched Bothered and Bewildered. Have I forgotten how to read a schematic? Did someone forget to send an important page in my kit? I received a pre assembled board so I'm assuming it's wired correctly. The NFB leads have me baffeled. In the instructions and the schematic and the wiring diagram on the website show one lead from each channel going to the output strip. My board came with a twisted pair from each channel. I've wracked my poor old brain and can not figgure out how to wire them. HELP

    Bob Latino
    Admin

    Posts : 2374
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Tubes4hifi VTA70 v12-ccs driver board HELP!

    Post by Bob Latino on Sat Feb 02, 2013 8:29 pm

    Charlie,

    On a stock ST-70 amp conversion to the VTA driver board > On both channels the 16 ohm tap on the terminal stip has a yellow wire from the transformer connected to that 16 ohm tap. There should also be another wire going from the 16 ohm tap to each of the two "NFB" eyelets on the STOCK ST-70 driver board which are eyelets 12 (left channel) and 13 (right channel). You just extend these two wires that once connected to eyelets 12 and 13 on the stock board to the two NFB eyelets on the VTA driver board.

    Bob

    charlief64

    Posts : 13
    Join date : 2012-12-21

    Thank You

    Post by charlief64 on Sat Feb 02, 2013 9:20 pm

    Thank you. Each pair that came soldered to the board has a green and a white wire. It looks like the white wire is a ground. Is that correct?
    Thanx again
    charlie

    Bob Latino
    Admin

    Posts : 2374
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Tubes4hifi VTA70 v12-ccs driver board HELP!

    Post by Bob Latino on Sun Feb 03, 2013 1:28 pm

    Charlie,

    Post a photo of the board with the wires - BUT - It is pretty simple for the NFB eyelets > A wire goes from each NFB eyelet to the 16 ohm tap on the two speaker terminal strips.

    Bob

    charlief64

    Posts : 13
    Join date : 2012-12-21

    Driver board photo

    Post by charlief64 on Sun Feb 03, 2013 6:12 pm

    The green wire in the pair go to the NFB eyelet. The white wire goes to the boards ground. So with the green wire to the 16 ohm post I think I'm good. Cant get the picture to be larger sorry

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Tubes4hifi VTA70 v12-ccs driver board HELP!

    Post by tubes4hifi on Tue Feb 05, 2013 9:53 pm

    Hi Charlie,
    yes, the green wire is NFB and the white wire is ground.
    BTW, do you have the ground wire of the speaker outputs grounded to chassis?
    It won't work correctly if you don't.
    You don't really need to connect the other end of the white wires, as it's already grounded on the PCB, it's just their as a "shield".
    Connecting them would actually form a couple of ground loops . . .


    charlief64

    Posts : 13
    Join date : 2012-12-21

    Driverboard

    Post by charlief64 on Thu Feb 07, 2013 1:29 am

    Yes. the speaker ground is grounded to the chassis. I thought the white wire might act as a shield. It is not connected to any thing. Thank you for your help
    Charlie

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