The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    PAS3 power supply

    Share

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    PAS3 power supply

    Post by tubes4hifi on Thu Jul 11, 2013 4:45 pm

    I thought I posted this somewhere about 6 months ago but now I can't find it, and it's useful info I use almost every week trying to help someone,
    so I'm posting this info here as a sticky so it's easy to find
    If you do ANY mods to a PAS3 it's likely you'll need to make changes to the power supply

    PAS3 power supply

    Pillo69

    Posts : 105
    Join date : 2012-04-11
    Location : Granada (España)

    Re: PAS3 power supply

    Post by Pillo69 on Tue Oct 22, 2013 6:59 am

    Thanks for the article, very interesting.

    As in ST70 there is a modification of the filter capacitor, placing one new 80-40-30 20uF, I would like to know whether PAS exists the possibility to replace the 20-20-10-30uF.

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    Re: PAS3 power supply

    Post by tubes4hifi on Tue Oct 22, 2013 10:42 am

    someone could easily replace the PAS3 quad cap, but for about $10 more you can replace it and the entire power supply with better parts!

    GP49

    Posts : 733
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: PAS3 power supply

    Post by GP49 on Tue Oct 22, 2013 11:21 am

    Upgrading the PAS power supply is really pretty easy. The selenium rectifier and the old filament smoothing capacitors take up a lot more space than modern parts.

    If you need more room, you can do as Frank Van Alstine does: mount the power transformer OUTSIDE the back panel where it will also have the benefit of open air to cool it. This also gets any potential hum fields from the transformer out where the steel chassis will shield them from the circuitry inside the unit...particularly important if you are using a different transformer that isn't totally encased in steel as is the original Dynaco. It doesn't look good, but who looks at the backside of your preamp, besides you? It does require clearance to the back of whatever cabinet you may want to use (if any) but if you are already intending to use super-size firehose-like interconnects, you'll need even more space than that!

    Pillo69

    Posts : 105
    Join date : 2012-04-11
    Location : Granada (España)

    Re: PAS3 power supply

    Post by Pillo69 on Tue Oct 22, 2013 5:53 pm

    tubes4hifi wrote:someone could easily replace the PAS3 quad cap, but for about $10 more you can replace it and the entire power supply with better parts!
    I do not want to place a capacitor bottle, simply place a printed circuit board with 4 independent capacitors.
    So wondering if it is possible to expand the capacity of said capacitors for better filtering.

    GP49

    Posts : 733
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: PAS3 power supply

    Post by GP49 on Tue Oct 22, 2013 6:13 pm

    Pillo69 wrote:
    tubes4hifi wrote:someone could easily replace the PAS3 quad cap, but for about $10 more you can replace it and the entire power supply with better parts!
    I do not want to place a capacitor bottle, simply place a printed circuit board with 4 independent capacitors.
    So wondering if it is possible to expand the capacity of said capacitors for better filtering.
    =============================================================

    Yes.  Easily and frequently done with virtually all of the add-on power supply capacitor boards.

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    Re: PAS3 power supply

    Post by tubes4hifi on Tue Oct 22, 2013 8:46 pm

    my standard power supply for the PAS3 has 266uF of B+ capacitance and 6600uF of filament capacitance,
    compared to the original of 90uF and 4400uF
    www.tubes4hifi.com/PAS3-CAT.htm

    Pillo69

    Posts : 105
    Join date : 2012-04-11
    Location : Granada (España)

    Re: PAS3 power supply

    Post by Pillo69 on Sun Oct 27, 2013 2:48 pm

    I got the information I wanted about the capacitors in SDS page Audio Labs
    If anyone needs information click here.

    http://www.quadesl.com/pdf/pas_capboard.pdf

    Sponsored content

    Re: PAS3 power supply

    Post by Sponsored content Today at 10:30 pm


      Current date/time is Sun Dec 04, 2016 10:30 pm