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    Got me a Dynaco SCA-35 again

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    peterh

    Posts : 1068
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Got me a Dynaco SCA-35 again

    Post by peterh on Mon Jun 11, 2018 10:15 am

    Just received a used SCA-35 from an auction site in sweden.
    Slightly damaged in transport, but noting that cannot be fixed, damaged fuze holder but
    apart from that no problems powering it up after cleaning.

    It is "user built" a long time ago, but most on the solderings are ok, cable dressing
    fully acceptable, and it seems to be in original condition. All tubes are "dynaco" marked !

    I am planning to install an EFB kit and an IEC well, then i will see if it has full power
    or if i need to switch power tubes. 7199 seems quiet, thus i keep then for time beeing.
    The (simple) power switch might be replaced as it was : 1/ single phase and 2/ slightly stuck. I think i have spares somewhere. Pots and selector works ok and needs no work.

    If any interest i can send pictures and work log .

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    Peter W.

    Posts : 1019
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Got me a Dynaco SCA-35 again

    Post by Peter W. on Mon Jun 11, 2018 10:28 am

    peterh wrote:Just received a used SCA-35 from an auction site in sweden.
    Slightly damaged in transport, but noting that cannot be fixed, damaged fuze holder but
    apart from that no problems powering it up after cleaning.

    It is "user built" a long time ago, but most on the solderings are ok, cable dressing
    fully acceptable, and it seems to be in original condition. All tubes are "dynaco" marked !

    I am planning to install an EFB kit and an IEC well, then i will see if it has full power
    or if i need to switch power tubes. 7199 seems quiet, thus i keep then for time beeing.
    The (simple) power switch might be replaced as it was : 1/ single phase and 2/ slightly stuck. I think i have spares somewhere. Pots and selector works ok and needs no work.

    If any interest i can send pictures and work log .


    Those are sweet little amps - for now, I suggest you keep in 100% original (but for the hardware, of course) until you are fully acquainted with its functions and behavior. You may decide that any modifications are unnecessary.

    I have a small boatload of 7199s, should the need arise. What with three amps that use them, I have gathered them in as I come across them.
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    corndog71

    Posts : 672
    Join date : 2013-03-19
    Location : It can get windy here

    Re: Got me a Dynaco SCA-35 again

    Post by corndog71 on Mon Jun 11, 2018 11:53 am

    I highly recommend the EFB upgrade as it lowers distortion and increases power slightly. It also keeps the B+ matched to the AC line unlike the stock bias circuit. It's an easy upgrade and reversible if needed.
    avatar
    peterh

    Posts : 1068
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Got me a Dynaco SCA-35 again

    Post by peterh on Tue Jun 12, 2018 4:34 am

    At a first examination : All tubes have Dynaco markings. Amazing that the EL84 have survived 40 years and still works.
    The amp works , no hum some scratches of pots and switches, nothing that some 5-56 cannot cure.
    Later i will trace some tubecurves of the oldies and also measure voltages comparing to the
    manual. In addition a full power test will reveal it's power. Stay tuned for some time.
    avatar
    Bob Latino
    Admin

    Posts : 2707
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Got me a Dynaco SCA-35 again

    Post by Bob Latino on Tue Jun 12, 2018 8:59 am

    peterh wrote:At a first examination : All tubes have Dynaco markings. Amazing that the EL84 have survived 40 years  and still works.
    The amp works , no hum some scratches of pots and switches, nothing that some 5-56 cannot cure.
    Later i will trace some tubecurves of the oldies and also measure voltages comparing to the
    manual. In addition a full power test will reveal it's power. Stay tuned for some time.

    The original Dynaco SCA-35 came out in 1964 so some of these units are now over 50 years old. These are nice amps ...  If used with efficient speakers (92 - 93 dB and above efficiency), they can provide room filling sound. If you intend to use the amp as a daily driver, I would rebuild the amp with new boards and clean all the controls.

    Below is the test data done by Stereo Review magazine 54 years ago ..

    Bob



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