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    PAS 3, need help with replacement caps

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    lobby

    Posts : 18
    Join date : 2011-02-15

    PAS 3, need help with replacement caps

    Post by lobby on Thu Apr 14, 2011 3:21 pm

    I am replacing some of the old caps in my PC-5 to see if I can solve my inoperable right channel issue.

    I have the values for these caps, but i was wondering what voltage I should get?



    the caps are

    6800pF
    1500pF
    33pF

    Any particular brand I should look at? Im not really going for high budget...

    (the green caps have already been replaced with sprauges)

    Bob Latino
    Admin

    Posts : 2373
    Join date : 2008-11-26
    Location : Massachusetts

    Re: PAS 3, need help with replacement caps

    Post by Bob Latino on Thu Apr 14, 2011 3:52 pm

    Two of those arrows (upper left and lower right) are pointing to what looks like 500 volt silver mica caps. It appears to me that those caps are already "replacement caps" because the original Dynaco PAS preamp boards did not come with silver mica capacitors. Silver mica capacitors are nearly always dead stable.

    You should replace those "black cat" capacitors. These are the original caps that the board came with and are probably 40 + years old.

    Bob

    lobby

    Posts : 18
    Join date : 2011-02-15

    Re: PAS 3, need help with replacement caps

    Post by lobby on Thu Apr 14, 2011 4:02 pm

    Do I need to replace the black cats even if i plan on bypassing the tone controls?

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: PAS 3, need help with replacement caps

    Post by tubes4hifi on Sun Apr 17, 2011 8:23 pm

    looking at the schematic answers your questions, the 7500pf caps (6800pf replacements work fine) are part of the bass controls,
    so aren't needed if the tone controls are bypassed, all of the caps in the photo are marked as 400vdc

    j4570

    Posts : 141
    Join date : 2010-08-30

    Re: PAS 3, need help with replacement caps

    Post by j4570 on Thu Apr 21, 2011 6:23 pm

    Those puke green caps are old too. I replaced some similiar to those in my Bogen tube amp as one was bad (it had 4).

    So I'd get rid of those too. Mine were from 1964.......

    Jason

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