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The Dynaco Tube Audio Forum

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


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    PAS 3 Balance Control Replacement Options?

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    breading

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    Join date : 2010-01-08

    PAS 3 Balance Control Replacement Options? Empty PAS 3 Balance Control Replacement Options?

    Post by breading Fri Oct 01, 2021 5:30 pm

    Is there a viable option for replacing existing balance control in my PAS 3???
    Bob Latino
    Bob Latino
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    PAS 3 Balance Control Replacement Options? Empty Re: PAS 3 Balance Control Replacement Options?

    Post by Bob Latino Fri Oct 01, 2021 6:37 pm

    breading wrote:Is there a viable option for replacing existing balance control in my PAS 3???

    These will be tough to find unless you can run across (on Ebay?) a non functioning PAS-3 at a low price with a good balance control. What you need is a 750K dual channel ganged potentiometer with a knurled shaft.

    Bob
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    breading

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    Join date : 2010-01-08

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    Post by breading Fri Oct 01, 2021 7:34 pm

    Bob,
    Am I correct that there are no current producers of a replacement pot for the PAS3?

    I see on eBay that "re-engineer" sells a kit with volume, balance, and blend. Any idea if what he offers is a viable solution?
    Bruce
    Bob Latino
    Bob Latino
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    Post by Bob Latino Fri Oct 01, 2021 7:56 pm

    breading wrote:Bob,
    Am I correct that there are no current producers of a replacement pot for the PAS3?  

    I see on eBay that "re-engineer" sells a kit with volume, balance, and blend.  Any idea if what he offers is a viable solution?
    Bruce

    You could Email "re-engineer" on Ebay and see if he would sell you the balance control separately ? I know of no other vendor that sells a direct replacement balance control for the PAS-3 preamp.

    Bob

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    jwb474

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    PAS 3 Balance Control Replacement Options? Empty Re: PAS 3 Balance Control Replacement Options?

    Post by jwb474 Sat Oct 02, 2021 3:06 pm

    If re-engineer ( I believe this is the guy - https://dynacodesigns.wordpress.com/dynaco-design-products/ ) can't supply a replacement you should be able to use this part, https://www.ebay.com/itm/282427375385?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649. I got the 500K version.

    The drawback is you will loose a little max level. With the original 750k pot and you set the volume to max and the balance to one side and apply 1v to the tape input, then you will get 0.7988v to the PC-5 assembly.
    With the 500K pot you will get 0.7800v. You may be able to live with this. If not then the 47K resistor that feeds the blend switch can be changed to 42.2k. The overall input resistance will still be a little lower, but should be OK.

    Now, maybe the folks here can help me out. The very special tone controls used on the Pas are just impossible to deal with if you have a problem. There was a guy that re-designed the tone network to use more conventional pots that you can get, but I have been unable at finding the info. Does anyone point me to the site with the info?
    tubes4hifi
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    PAS 3 Balance Control Replacement Options? Empty Re: PAS 3 Balance Control Replacement Options?

    Post by tubes4hifi Fri Oct 08, 2021 9:25 pm

    I used to sell tone replacement kits about ten years ago but quit selling anything having to do with the PAS3.
    There's likely some posts on the forum about it somewhere.
    OK, I found some old documentation buried in the depths of my computer archives.
    Only problem is I can't remember which pot is linear and which one is logarithmic.
    But 99% sure the 300K treble is linear and the 500K bass is log taper. (you could measure the existing ones and figure it out)
    (if it's linear, the halfway position will measure half of max, if log, about 15% of max)
    You can find both of these at tubesandmore.com in the potentiometer section.


    the Dynaco PAS2 and PAS3 are identical electronically and differ only by the front panel and knobs.
    the Dynaco PAS3-X is also identical but uses a special type of control,
    these parts can be substituted with no problems

    2 – 300K TREBLE controls – these replace the originals
    2 – 500K BASS controls – these replace the originals
    2 – 0.002 capacitors (222K) – these replace the originals
    2 – 0.02 capacitors (223K) – these replace the originals
    2 – 1.0uF capacitors (105J) – these replace the originals
    these were not used in the PAS2 but can be added between the CW lug of the bass control
    and eyelet # 5 on left channel and eyelet # 12 on right channel

    Replace each part and wire identical to the way it was.
    If you need instructions, refer to the PAS3 manual, pages 5 & 6, which can be downloaded from here:
    www.tubes4hifi.com/downloads.htm

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