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    Replacing the caps in my ST70

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    kimla

    Posts : 4
    Join date : 2009-12-11

    Replacing the caps in my ST70

    Post by kimla on Sun Jan 10, 2010 4:34 pm

    I loaned my ST 70 to my son, when he went to college, and it came back dead, so I'm in
    process of reserecting it... replacing the pc board, the quad cap, and the bias caps.
    I want to know about the 2X.02 uF dual disk cap. Can I replace it with two .02's, should I?
    I haven't found a replacement 2X. Thanks for your help!
    k

    Bob Latino
    Admin

    Posts : 2414
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Replacing the caps in my ST70

    Post by Bob Latino on Sun Jan 10, 2010 5:28 pm

    kimla wrote:I loaned my ST 70 to my son, when he went to college, and it came back dead, so I'm in
    process of reserecting it... replacing the pc board, the quad cap, and the bias caps.
    I want to know about the 2X.02 uF dual disk cap. Can I replace it with two .02's, should I?
    I haven't found a replacement 2X. Thanks for your help!
    k

    Hi,

    Yes - You can replace that dual .02 uF cap on lugs 5, 6 and 7 of the 7 lug terminal strip with two single .02 uF caps. Anything 100 volt or higher rating would work fine. All these caps do is ground the center taps of the two 6.3 volt AC windings. They don't look at much voltage ..

    Bob

    kimla

    Posts : 4
    Join date : 2009-12-11

    Re: Replacing the caps in my ST70

    Post by kimla on Mon Jan 11, 2010 11:03 pm

    Thanks Bob. That is what I thought, but good to make sure.
    I work with a bunch of electrical engineers, but they are power engineers, to the man, so they've forgotten a lot of their electronics training. Although one guy was brave enough to say, "yeah, I think that would work"...

    Luddite

    Posts : 235
    Join date : 2009-02-04
    Age : 66
    Location : Texas

    Re: Replacing the caps in my ST70

    Post by Luddite on Tue Jan 12, 2010 2:54 pm

    Just an anecdote: I built a "ST-70" in 1991 by ordering the chassis, cage, transformers, and a few other parts from Sound Valves and the driver board from Frank Van Alstine. One of the items I ordered from Sond Valves was the dual .02mf cap. The cap I received was actually made up from two .02mf caps which had one each of their leads twisted and soldered together.

    Charlie

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