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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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    My ST120 build so far

    Rbertalotto
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    Rbertalotto


    Posts : 98
    Join date : 2021-02-25
    • Post n°1

    My ST120 build so far Empty My ST120 build so far

    Post by Rbertalotto Sat Mar 06, 2021 11:11 am

    Started on my ST120 yesterday......Main circuit board is done, built the time delay relay board (TDR), painted the transformers and started the chassis wiring. Pretty easy so far. The instructions are fantastic. The boards are beautifully manufactured. Clearly labeled and quality solder lands. Trying to keep all the point to point wiring neat is a real challenge. I'm not half done and its already starting to get "
    Rat's Nesty"

    My ST120 build so far IMG_20210305_174300047-vi

    My ST120 build so far IMG_20210305_174315347-vi

    My ST120 build so far IMG_20210306_092310965-vi

    My ST120 build so far IMG_20210306_092257431-vi

    My ST120 build so far IMG_20210305_0908073062-vi
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    Rbertalotto
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    Rbertalotto


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    • Post n°2

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Rbertalotto Sat Mar 06, 2021 4:03 pm

    I wonder if the LEDs can be relocated to a place where you can see them? Strange that they are on the board and then buried inside the chassis.
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    Bob Latino
    Bob Latino
    Bob Latino
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    • Post n°3

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Bob Latino Sun Mar 07, 2021 1:51 pm

    Rbertalotto wrote:I wonder if the LEDs can be relocated to a place where you can see them? Strange that they are on the board and then buried inside the chassis.

    Hi Roy ... A real nice job on your amp ... Thanks for the photos ..

    The TWO LED's on the board are just there to let you know ..

    RED LED > The board is properly powered with 6.3 volts AC
    GREEN LED > The relay is working to switch on the two high voltage lines from the power transformer.

    You should test the TDR before the first startup procedure of the amp as listed in the short assembly manual for the TDR as below.

    "After the amp is completed you should test the VTA-TDR board before attempting to play the amp. Remove all the tubes and turn the amp ON. The RED LED should come on immediately (the GREEN LED may light up very dimly also) and after about 17 - 20 seconds you should hear the relay "click" and the GREEN LED should come on brightly and the RED LED should go OFF"

    If this is what happens, then the TDR is working fine. Note > You can hear the "click" of the relay after the amp is assembled and the bottom cover is back on. IMHO > You don't really need to see the LED's from the top of the amp .. The CLICK will tell you that the TDR has done its job.

    Bob
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    Rbertalotto
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    Rbertalotto


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    • Post n°4

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Rbertalotto Sun Mar 07, 2021 4:21 pm

    Thanks Bob....I'll do the test as advised. Do I remove the solid state rectifier also?

    Just for "bling". can those LEDs be relocated without any audio degradation?
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    Rbertalotto
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    Rbertalotto


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    • Post n°5

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Rbertalotto Sun Mar 07, 2021 4:23 pm

    A little more done....

    My ST120 build so far IMG_20210307_072001484-vi

    My ST120 build so far IMG_20210307_071951532-vi

    My ST120 build so far IMG_20210307_071935374-vi
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    Bob Latino
    Bob Latino
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    • Post n°6

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Bob Latino Sun Mar 07, 2021 5:53 pm

    Rbertalotto wrote:Thanks Bob....I'll do the test as advised. Do I remove the solid state rectifier also?

    Just for "bling". can those LEDs be relocated without any audio degradation?

    1. Do the test WITHOUT the solid state rectifier in the amp. Then test to see that you get about 400 - 420 volts AC from pin 4 and pin 6 on the rectifier tube socket to chassis ground.

    2. You could relocate the LED's elsewhere as long as you know what you are doing ?

    Bob

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    Rbertalotto
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    Rbertalotto


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    • Post n°7

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Rbertalotto Mon Mar 08, 2021 8:00 pm

    IT'S DONE!   I'll do circuit  trace testing and relay board testing  tomorrow before I fire it up. Total build time 9 hours. Didn't have any issues so far., The instructions are fantastic. Along with the pictures its a pretty easy build.....We'll see how it goes when I turn it on!

    My ST120 build so far DSC_6869-vi

    My ST120 build so far IMG_20210308_1837397622-vi

    My ST120 build so far IMG_20210308_183756828-vi

    My ST120 build so far IMG_20210308_183823807-vi

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    cci1492
    cci1492
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    Post by cci1492 Tue Mar 09, 2021 2:48 pm

    Absolutely gorgeous job, well done!
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    Section1
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    Section1


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    • Post n°9

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    Post by Section1 Tue Mar 09, 2021 10:03 pm

    Looks really good. Nice job!
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    Rbertalotto
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    Rbertalotto


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    • Post n°10

    My ST120 build so far Empty Re: My ST120 build so far

    Post by Rbertalotto Tue Mar 09, 2021 10:26 pm

    I posted a few videos of the testing and final music playing here:

    https://public.fotki.com/Rbertalotto/hifi-stereo-stuff/vta-dynaco-st-120/
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