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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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    weird observation with my A470 output transformers

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    Sichum


    Posts : 5
    Join date : 2021-01-16

    weird observation with my A470 output transformers Empty weird observation with my A470 output transformers

    Post by Sichum Mon Jan 02, 2023 8:37 pm

    Greeting,

    While checking my st-70 for possible shortage, I noticed there is continuity between the chassis and every speaker posts. Thinking those speaker terminals were shortage somehow, I removed all wires and redo them all and tested without the output transformer wires connected. No continuity. I thought that was great and went ahead solder those wires back into place. I tested them again after soldered them and the continuity was there again. Is that behavior expected? if not, what's going on there? Any help is much appreciated. Thank you
    peterh
    peterh


    Posts : 1718
    Join date : 2012-12-25
    Location : gothenburg, sweden

    weird observation with my A470 output transformers Empty Re: weird observation with my A470 output transformers

    Post by peterh Mon Jan 02, 2023 9:07 pm

    Sichum wrote:Greeting,

    While checking my st-70 for possible shortage, I noticed there is continuity between the chassis and every speaker posts. Thinking those speaker terminals were shortage somehow, I removed all wires and redo them all and tested without the output transformer wires connected. No continuity. I thought that was great and went ahead solder those wires back into place. I tested them again after soldered them and the continuity was there again. Is that behavior expected? if not, what's going on there? Any help is much appreciated. Thank you
    The common output is grounded in the amp, this serves as reference as the 16ohm
    is used for NFB

    Have a look in the schematics !

    Sichum likes this post

    avatar
    Sichum


    Posts : 5
    Join date : 2021-01-16

    weird observation with my A470 output transformers Empty Re: weird observation with my A470 output transformers

    Post by Sichum Thu Jan 05, 2023 3:31 pm

    peterh wrote:
    Sichum wrote:Greeting,

    While checking my st-70 for possible shortage, I noticed there is continuity between the chassis and every speaker posts. Thinking those speaker terminals were shortage somehow, I removed all wires and redo them all and tested without the output transformer wires connected. No continuity. I thought that was great and went ahead solder those wires back into place. I tested them again after soldered them and the continuity was there again. Is that behavior expected? if not, what's going on there? Any help is much appreciated. Thank you
    The common output is grounded in the amp, this serves as reference as the 16ohm
    is used for NFB

    Have a look in the schematics !

    much appreciated for your time. I read more about the NFB and starting to understand a bit more.

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    weird observation with my A470 output transformers Empty Re: weird observation with my A470 output transformers

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