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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


    Random shock turning off ST-70

    polarflux
    polarflux

    Posts : 50
    Join date : 2010-02-12
    Location : Alaska

    Random shock turning off ST-70 Empty Random shock turning off ST-70

    Post by polarflux on Mon Oct 12, 2020 11:15 pm

    Hey all,

    Just wondering why after all these years my Tubes for Hifi ST-70 a family member (my daughter) turning off the amp. I was outside at the time so I wasn't there to see it, but when she touched the switch the amp shocked her burning her hand a bit. She is fine, but the amp definitely juiced her a bit. She did have her phone in her other hand. I didn't test the amp when I came, I simply unplugged it, but the rectifier tube didn't appear to have blown, nor was the fuse blown. I've never had the amp shock me and I have not done anything to it recently to cause any damage to it. Ideas? By the way, I've had the amp now for about 11 years.

    Thanks

    Phil
    peterh
    peterh

    Posts : 1434
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Random shock turning off ST-70 Empty Re: Random shock turning off ST-70

    Post by peterh on Tue Oct 13, 2020 12:09 am

    polarflux wrote:Hey all,

    Just wondering why after all these years my Tubes for Hifi ST-70 a family member (my daughter) turning off the amp. I was outside at the time so I wasn't there to see it, but when she touched the switch the amp shocked her burning her hand a bit. She is fine, but the amp definitely juiced her a bit. She did have her phone in her other hand. I didn't test the amp when I came, I simply unplugged it, but the rectifier tube didn't appear to have blown, nor was the fuse blown. I've never had the amp shock me and I have not done anything to it recently to cause any damage to it. Ideas? By the way, I've had the amp now for about 11 years.

    Thanks

    Phil
    Make a full examination of power side. Then install a grounded outlet and change the
    power cord to a full grounded 3 prong cable.
    Bob Latino
    Bob Latino
    Admin

    Posts : 2959
    Join date : 2008-11-26
    Location : Massachusetts

    Random shock turning off ST-70 Empty Re: Random shock turning off ST-70

    Post by Bob Latino on Tue Oct 13, 2020 8:25 am

    polarflux wrote:Hey all,

    Just wondering why after all these years my Tubes for Hifi ST-70 a family member (my daughter) turning off the amp. I was outside at the time so I wasn't there to see it, but when she touched the switch the amp shocked her burning her hand a bit. She is fine, but the amp definitely juiced her a bit. She did have her phone in her other hand. I didn't test the amp when I came, I simply unplugged it, but the rectifier tube didn't appear to have blown, nor was the fuse blown. I've never had the amp shock me and I have not done anything to it recently to cause any damage to it. Ideas? By the way, I've had the amp now for about 11 years.

    Thanks

    Phil

    I am thinking that after 11 years the power switch shorted and/or is somehow now defective. Try just replacing the power switch .. Dynakitparts sells a replacement power switch. Link below .. You would want the SPST power switch ....

    Dynakitparts slide switches

    Bob
    PeterCapo
    PeterCapo

    Posts : 921
    Join date : 2008-12-05

    Random shock turning off ST-70 Empty Re: Random shock turning off ST-70

    Post by PeterCapo on Tue Oct 13, 2020 8:32 am

    Good grief, don't take any chances with that.  Can't say what it might be, but until you get it figured out you could add a layer of possible protection by employing a GFCI.  

    Here is one example: https://www.amazon.com/TRC-14650006-6-Shockshield-Protection-Unmonitored/dp/B000XVG72G/ref=sr_1_35?crid=2AGWZ5LBL9V22&dchild=1&keywords=gfci+power+strip&qid=1602592117&sprefix=GFCI+power%2Caps%2C161&sr=8-35

    Here's another: https://www.grainger.com/product/SOUTHWIRE-GFCI-Power-Strip-8RG12

    Sponsored content

    Random shock turning off ST-70 Empty Re: Random shock turning off ST-70

    Post by Sponsored content


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