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    Removing DC voltage from pas 3x output

    Westy56
    Westy56

    Posts : 58
    Join date : 2011-05-09
    Location : Albuquerque

    Removing DC voltage from pas 3x output Empty Removing DC voltage from pas 3x output

    Post by Westy56 on Wed Sep 26, 2012 12:44 pm

    This http://curcioaudio.com/PAS%202-3-X%20Tone%20Control%20Removal.pdf is the by-pass I followed

    Can I put the 1 uF cap in after the PC5 board in series with the wire that leads to the main output?

    Using the left channel as example, apparently someone used the cap between #6-#7 on the board. I guess that works.
    Just hoping to not solder on the board again.

    Any guidance will be appreciated.


    Steve

    tubes4hifi
    tubes4hifi
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    Removing DC voltage from pas 3x output Empty Re: Removing DC voltage from pas 3x output

    Post by tubes4hifi on Wed Sep 26, 2012 1:35 pm

    you shouldn't need the extra cap if you jumpered eyelet 6 to eyelet 5 or 7, see attached schematic, as there is also the .22uF cap on the board



    Removing DC voltage from pas 3x output PAS3schematic5
    Westy56
    Westy56

    Posts : 58
    Join date : 2011-05-09
    Location : Albuquerque

    Removing DC voltage from pas 3x output Empty Re: Removing DC voltage from pas 3x output

    Post by Westy56 on Wed Sep 26, 2012 2:13 pm

    I think you are a member at AK, so this picture should show.
    The yellow lines represent the jumpers. I did the mod per the sites instructions.

    Removing DC voltage from pas 3x output Pc5

    I'm getting about .7 DCV at the output
    Maybe leaky capacitors, it is stock.

    Thanks,


    Steve
    tubes4hifi
    tubes4hifi
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    Removing DC voltage from pas 3x output Empty Re: Removing DC voltage from pas 3x output

    Post by tubes4hifi on Wed Sep 26, 2012 6:50 pm

    If you've got voltage there I would add a cap from eyelet 7 to the output jack, 0.22uF is big enough.
    The small amount of voltage is probably coming from the first stage cathode thru the 47K at eyelet 4 (part of the feedback loop),
    which has now been jumped to eyelet 6.
    Westy56
    Westy56

    Posts : 58
    Join date : 2011-05-09
    Location : Albuquerque

    Removing DC voltage from pas 3x output Empty Re: Removing DC voltage from pas 3x output

    Post by Westy56 on Thu Sep 27, 2012 6:55 am

    tubes4hifi wrote:If you've got voltage there I would add a cap from eyelet 7 to the output jack, 0.22uF is big enough.
    The small amount of voltage is probably coming from the first stage cathode thru the 47K at eyelet 4 (part of the feedback loop),
    which has now been jumped to eyelet 6.

    Thanks very much. I'm actually impressed with this little preamp, dead quiet on idle.
    The tone by-pass and replacement of the 2000 uF caps made the biggest difference so far.


    Steve

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