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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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    Mark 3 Transformers

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    jwb474


    Posts : 89
    Join date : 2014-07-13
    Age : 71
    Location : Wolfforth, Tx

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    Post by jwb474 Tue May 22, 2018 4:32 am

    I am getting ready for some future Mark 3 work. Going thru the manual folder I notice I had 2 different manuals.

    The output transformer from one manual identifies the transformer "Z-216" and the other manual has "A-431" Does anyone know what the difference is?
    DynakitParts lists the transformer as A-431.

    Moving on to the input transformer: The schematic of one manual has 117VAC input and the DC voltage on the 2nd cap is 480VDC. The transformer is labeled "P-782".
    The other schematic has 120VAC input and voltage on the 2nd cap is also 480VDC. The transformer is also labeled "P-782" Now with the same DC voltage and 2 different AC inputs,
    the transformer has to be different, but is labeled the same. Does anyone have any info on the difference?
    WLT
    WLT


    Posts : 189
    Join date : 2013-07-13
    Location : Rochester NY

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    Post by WLT Tue May 22, 2018 8:34 am

    More info but no real answer for you. I have four manuals from different vintages. Here is the info from them

    North 43 Street, Serial number 3743002, 117 V AC, 480 V DC, A431
    Powelton ave, Serial number 3052064, 117 V AC, 480 V DC, A431
    Jefferson Street, Serial number 3409086, 120 V AC, 480 V DC, Z216
    Jefferson Street, Serial number 3409101, 120 V AC, 480 V DC, Z216

    I purchased the last two amps as new kits in the spring of 1974. From date codes I have seen on many Z216 I believe they are the later version with PVC wiring. My two Mark II manuals list 117 VAC and A431/430 but 465 VDC as the rectifier and choke are different.

    The question about the P 782 power transformer is a little difficult to track down. Hopefully others have some good info.
    Roy Mottram
    Roy Mottram
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    Post by Roy Mottram Wed May 23, 2018 4:30 pm

    Dynaco transformers starting with a Z were made in Japan rather than USA, otherwise identical (at least that's what I remember from 25 years ago . . . )
    j beede
    j beede


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    Join date : 2011-02-07
    Location : California

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    Post by j beede Wed May 23, 2018 9:58 pm

    tubes4hifi wrote:Dynaco transformers starting with a Z were made in Japan rather than USA, otherwise identical (at least that's what I remember from 25 years ago . . . )

    Maybe you meant to say electrically identical. I know that with the Mark VI the Japanese transformers certainly look much different than their domestic counterparts. This may not be the case with the Mk III. I have owned and worked on many Mk III and have not seen one personally with a transformer marked with a Z.
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    Guest
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    Post by Guest Thu May 24, 2018 10:45 pm

    .


    Last edited by PeterCapo on Mon Nov 30, 2020 6:06 pm; edited 1 time in total
    WLT
    WLT


    Posts : 189
    Join date : 2013-07-13
    Location : Rochester NY

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    Post by WLT Sat May 26, 2018 8:47 am

    To follow up on J Beede comment. From what I have seen. The A430 and A431 transformers all seem to have their number stamped into the end bell. The Z series does not have the Z216 label anywhere on the end bells. What I do see is a ZTOXXX designation that is stenciled on. Just below that is the date code. Not stamped. Attached is one of my MK III with ZTO195.

    Have others found different results?
    Mark 3 Transformers Img_2811
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    jwb474


    Posts : 89
    Join date : 2014-07-13
    Age : 71
    Location : Wolfforth, Tx

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    Post by jwb474 Sun May 27, 2018 1:40 pm

    WLT wrote:To follow up on J Beede comment. From what I have seen. The A430 and A431 transformers all seem to have their number stamped into the end bell. The Z series does not have the Z216 label anywhere on the end bells. What I do see is a ZTOXXX designation that is stenciled on. Just below that is the date code. Not stamped. Attached is one of my MK III with ZTO195.

    Have others found different results?
    Mark 3 Transformers Img_2811

    I have verified I have the same markings on the gray bell transformers along with the same silk screening on the chassis showing 117VAC. These also have the brown cages. I do have a couple of MK3s with black cages and the silkscreen does not show any of the input ratings, but the color of the bells are gray. When I get industrious, I will open them up and see what markings there are.

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