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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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    Triode/Pentode Toggle Switch Source?

    heyraz
    heyraz
    heyraz


    Posts : 59
    Join date : 2011-10-26
    • Post n°1

    Triode/Pentode Toggle Switch Source? Empty Triode/Pentode Toggle Switch Source?

    Post by heyraz Wed Dec 28, 2011 11:48 am

    The bias pot holes on my ST70 measure 3/8" diam but I cannot find a DPDT toggle that fits. Every time I think I've got one it's either too large or too small.
    Must I use a smaller diameter switch with a bushing or does someone have a source and part number for one that will fit? I feel so stupid...
    Thanks. Rich
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    Bob Latino
    Bob Latino
    Bob Latino
    Admin


    Posts : 3277
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    Triode/Pentode Toggle Switch Source? Empty Re: Triode/Pentode Toggle Switch Source?

    Post by Bob Latino Wed Dec 28, 2011 12:20 pm

    Hi Rich,

    There are no 3/8 inch diameter DPDT switches ... At least none that I know of .. You have to use a 1/4 (smaller) switch and place a washer around the switch on the top. Most 1/4 switches will have ONE washer that is larger than 3/8 on the outside. Place that one on the bottom and get two washers at your local hardware store that will slide over the top. The best washer to use is a 3/16" "USS" washer. Yes - I know that 3/16 is smaller than 1/4 inch but a 3/16 USS washer fits the best over a 1/4 inch switch. Most 1/4 switches are about .225 diameter to fit into a .250 hole. A 3/16 USS washer has a internal hole of almost exactly 1/4 inch (.250 inch)

    Bob
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    heyraz
    heyraz
    heyraz


    Posts : 59
    Join date : 2011-10-26
    • Post n°3

    Triode/Pentode Toggle Switch Source? Empty Re: Triode/Pentode Toggle Switch Source?

    Post by heyraz Wed Dec 28, 2011 9:35 pm

    Thanks, that explains a lot. I ended up making 2 thin bushings to fill out the holes from a 3/8" to 1/4" steel spacer I picked up at Lowes. I clamped the stock in a vice and used a Dremel to slice off 2 bushings thick enough to keep the 1/4" switch from moving around in the 3/8" hole. A stainless steel 3/16" washer on the top and bottom with lockwasher and nut finished up the job.
    Rich
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    • Post n°4

    Triode/Pentode Toggle Switch Source? Empty Re: Triode/Pentode Toggle Switch Source?

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