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    Optimum Resistor specs for ST-70?

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    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Optimum Resistor specs for ST-70?

    Post by Doctor Hugocat on Sun Sep 27, 2015 1:27 am

    Hey All -

    Apologies if this is a foolish question, but I'm about to order the resistors for my ST-70 project and I just realized that I don't know the specs I should be buying....1w or 1/2w? and the tolerance: 1%? 2%?

    I checked the parts list in the assembly manual, but since the parts were included in the it, they don't mention these specs: and I'm not sure where else to look.

    Thanks for any advice! Very Happy

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: Optimum Resistor specs for ST-70?

    Post by PeterCapo on Sun Sep 27, 2015 1:13 pm

    Are you talking the original design or one of the replacement circuits?

    If you are referring to the original, the smaller ones are 1/2W and the larger ones are 1W.  Bob has a sticky that should do the trick: http://dynacotubeaudio.forumotion.com/t191-dynaco-st-70-pc-3-driver-board-parts-layout-photo

    If you look at the original schematic, look for the resistors on the PCB that have asterisks next to them - these need to be 1%.  At different places throughout the amp, the rest of them vary from 5% to as much as 20% in some cases, I think.  But, these days, it's pretty easy to find 5% or better tolerance resistors.

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: Optimum Resistor specs for ST-70?

    Post by Doctor Hugocat on Sun Sep 27, 2015 3:24 pm

    Thanks Peter - Much appreciated.

    I should have said (but of course I forgot) - I'm going to buy a VTA driver board for the amp, so I'm only looking for resistors for the rest of the project. I'll go to the schematic and have a look to see if the non-PCB resistors are marked.

    study

    Tubes4ever

    Posts : 59
    Join date : 2015-07-14
    Location : Star, Idaho

    Re: Optimum Resistor specs for ST-70?

    Post by Tubes4ever on Sun Sep 27, 2015 8:37 pm

    Just buy 2 watt 5% resistors. They are cheap and you'll be sure to not be undersized.

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: Optimum Resistor specs for ST-70?

    Post by Doctor Hugocat on Sun Sep 27, 2015 11:49 pm

    Tubes4ever wrote:Just buy 2 watt 5% resistors.  They are cheap and you'll be sure to not be undersized.

    Awesome, thanks Tubes4ever! I'll do exactly that. Very Happy

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