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    Removing DC voltage from pas 3x output

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    Westy56

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

    Removing DC voltage from pas 3x output

    Post by Westy56 on Wed Sep 26, 2012 1:44 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
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Removing DC voltage from pas 3x output

    Post by tubes4hifi on Wed Sep 26, 2012 2:35 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




    Westy56

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

    Re: Removing DC voltage from pas 3x output

    Post by Westy56 on Wed Sep 26, 2012 3:13 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.



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

    Thanks,


    Steve

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Removing DC voltage from pas 3x output

    Post by tubes4hifi on Wed Sep 26, 2012 7:50 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

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

    Re: Removing DC voltage from pas 3x output

    Post by Westy56 on Thu Sep 27, 2012 7:55 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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