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    ST 70 Restoration Time Lapse/Condensed Video

    jrubin
    jrubin

    Posts : 85
    Join date : 2015-08-28

    ST 70 Restoration Time Lapse/Condensed Video Empty ST 70 Restoration Time Lapse/Condensed Video

    Post by jrubin on Sun Mar 22, 2020 10:45 am

    Here is the non-technical artistic version of the ST-70 amplifier restoration video for all to enjoy edited from the several full length videos that made up the original restoration. I make several of such videos a year for larger projects.


    DavidR
    DavidR

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    Join date : 2017-08-10
    Location : MetroWest, MA

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    Post by DavidR on Sun Mar 22, 2020 1:13 pm

    Neat !
    Loved the music, too.
    solderblob
    solderblob

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    Age : 74
    Location : Placerville, California

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    Post by solderblob on Sun Mar 22, 2020 3:38 pm

    Great entertaining video.  Thanks for posting it.

    dave
    jrubin
    jrubin

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    Join date : 2015-08-28

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    Post by jrubin on Mon Mar 23, 2020 8:47 am

    solderblob wrote:Great entertaining video.  Thanks for posting it.

    dave

    You're welcome. I should have pointed out that this was condensed from the project found here on this forum

    http://dynacotubeaudio.forumotion.com/t3996-the-st70-resurrection-continues-with-the-st70-resurrection-restoration-project
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    boeingpilot

    Posts : 22
    Join date : 2015-06-20
    Location : Central PA

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    Post by boeingpilot on Mon Mar 23, 2020 10:46 pm

    Nice workmanship! Can I ask why you chose to keep the selenium rectifier. I was of the impression that old selenium rectifiers could fail unpredictably.

    Same for the driver board? My first ST-70 had the old board like that, ended up having to replace as lands had lifted. That one has a tubes4hifi replacement, while my 2nd ST-70 just has a re-pop 7199 board made of better materials. Any concerns with the original board?
    jrubin
    jrubin

    Posts : 85
    Join date : 2015-08-28

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    Post by jrubin on Tue Mar 24, 2020 11:38 pm

    boeingpilot wrote:Nice workmanship!   Can I ask why you chose to keep the selenium rectifier.  I was of the impression that old selenium rectifiers could fail unpredictably.  

    Same for the driver board?  My first ST-70 had the old board like that, ended up having to replace as lands had lifted.  That one has a tubes4hifi replacement, while my 2nd ST-70 just has a re-pop 7199 board made of better materials.  Any concerns with the original board?

    It's a valid question. I'd promised myself that if in any of my equipment [in the entire collection] I was to have any occurrence of a selenium rectifier failure, especially something in a bias role and not delivering any considerable power, I would make it my business to replace all of them in my collection with whatever isn't exploding or failing in tube amplifiers today and worry about the next weakest link. That said, I've yet to have any issues, and never heard of any first hand accounts of them failing, especially in a bias role.

    I would think, that the increasing internal resistance over decades would eventually make it difficult to correctly bias tubes in this platform, long before catastrophic failure. IMHO. Should it ever reach that point for me, that would also be a reason for replacement as it would be useless in the amp.

    As for the original board, I cleaned it up and repaired it just because it was the original, and everyone tosses them. That's whats cool about it. It is repairable as you see and it works just fine.


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