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    Fuse blows when I put ST 70 on its side

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    kens770

    Posts : 7
    Join date : 2012-08-01

    Fuse blows when I put ST 70 on its side

    Post by kens770 on Mon Aug 06, 2012 9:21 pm

    I have a problem with my ST-70. I am rebuilding it and have it finished and want to test the voltages. However with the GZ34 plugged in when I tilt the amp on its side the amp make the sound of a transformer with a large in-rush current and then the fuse blows. I figure the GZ34 must have a loose plate, cathode, etc. I had the tube tested and of course it tested good.

    My question, is it possible for this to happen, tilting the amp and a fuse blows. I can turn the amp upside down without the GZ34 and nothing happens.

    Thanks again for your response.

    Ken

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: Fuse blows when I put ST 70 on its side

    Post by hawaii.ken on Tue Aug 07, 2012 1:15 am

    Check your HV wiring after the GZ34.

    Sal

    Posts : 223
    Join date : 2009-02-05
    Location : Central New Jersey Dynaco-ST70.com

    Re: Fuse blows when I put ST 70 on its side

    Post by Sal on Tue Aug 07, 2012 4:35 pm

    It can also be a bad output tube shorting when you tilt it, its a long shot but do not disregard it. Without the 5ar4 tube you are not feeding any B+ to the tubes.

    Sal

    DynakitParts
    Admin

    Posts : 181
    Join date : 2008-11-30

    Re: Fuse blows when I put ST 70 on its side

    Post by DynakitParts on Tue Aug 07, 2012 7:35 pm


    Ken,
    Could be a bad tube socket having loose contact with the pins when the amp turned sideways. A good method to support the ST-70 upside down to check the voltages is to remove the bottom cover and then install the top vented cover. Rest the amp on the top cover... Of course...having a top cover would work best.

    Kevin

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