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1947 RCA radio help

Discussion in 'Electronic Repair' started by Golf, Jul 25, 2007.

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  1. Golf

    Golf Guest

    A friend has this in a cabinet with phono player. The chassis # is
    RK-117. The amp/power supply seems to be missing. He said he found a
    number for the amp - CS-123 (or 125). The radio has AM, short wave,
    and FM. He wanted to try to get this going, so I told him I would ask
    this group for info on the power supply/amp parts availability and any
    other general knowledge about this particular radio. I would think we
    could install a modern PS and amp if we knew the requirements. Of
    course he also told me the radio has tubes in it, which I have no clue
    if replacements could be found in this old thing? If anyone here has
    some info, please feel free. I told my buddy I guarantee someone in
    this group will know something about this. Thanks as always.
     
  2. Don Bowey

    Don Bowey Guest

    The chassis probably has the radio, PS and amp, and he just doesn't
    recognize the parts. 1947 stuff wasn't terribly sophisticated by modern
    standards.

    See if you can get the tube lineup.
     
  3. Ken Weitzel

    Ken Weitzel Guest

    Hi...

    With all due respect, it would seem a shame to not restore it as
    close as possible to original...

    If nothing else comes up, he can buy the info here...

    http://www.olditemsale.com/rca/rca.htm

    Take care.

    Ken
     
  4. DaveM

    DaveM Guest

    Tubes are still widely available for these oldies, but some are a bit expensive.
    If the unit hasn't suffered terribly in damp storage, it might still be
    restorable.
    By all means, the first thing that should be done is to replace *ALL*
    electrolytic capacitors in the unit. Then, replace all the paper and paper-oil
    capacitors. The resistors can be checked with a good meter and left in place if
    not too far out of tolerance (usually 10%, but in some cases 20%).
    If you can't find a power supply chassis for this unit, you might have to build
    one. The schematic looks quite complete, and should contain sufficient detail
    for a construction project.

    Then, apply power and listen for radio noises. Keep in mind that they won't
    sound like the broadcasts of 1947, but should put out pretty good sound.
    If there's trouble, then I suggest that you post your questions and requests for
    guidance to the rec.antiques.radio+phono group... Terribly nice bunch of guys
    there (well, most of them are) and all are quite willing to help and give
    advice.
    --
    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
    address)

    "In theory, there isn't any difference between theory and practice. In
    practice, there is." - Yogi Berra
     
  5. Golf

    Golf Guest

    Thanks for reply. My buddy thinks an amp is missing since there is a
    round plug (more than 2 pins) hanging off the back of the receiver
    with no place to plug in and he saw a number for an amp. I haven't
    seen this thing yet, but we will give it our best to get going. He
    originally bought this simply because he liked the cabinet!
     
  6. Golf

    Golf Guest

    Thankyou to all that responded. I knew you guys wouldn't let me down.
    We are going to try to restore with original parts if needed, and will
    post follow up questions as needed to the group suggested. Thanks guys.
     
  7. R!

    R! Guest

    You may want to try this newsgroup:

    rec.antiques.radio+phono

    but a lot of us hang out here as well...

    R!
     
  8. PeterD

    PeterD Guest

    Consider that round plug went to the speaker, which had a 'dynamic'
    magnet (which served as the choke in the power supply).
     
  9. Golf

    Golf Guest

    I did ask him if it may be a speaker connection, he said no because
    the speaker was positioned in a location that I guess is away from
    this plug, and the speaker was already connected via? Thankyou for
    replying by the way.
     
  10. Golf

    Golf Guest

    Thank you. I will check it out!
     
  11. Guest

    It sounds like your friend would be best taking it to someone that
    knows the subject. Meanwhile the next best move would be to tell us
    what the valve/tube numbers in it are.

    Do ignore any advice to wholesale replace parts. Really you need to
    understand whats going on properly before working on it.


    NT
     
  12. DaveM

    DaveM Guest

    By all means, a good understanding of circuit operation and troubleshooting
    technique is highly desirable before starting to work on a complicated piece of
    equipment.
    I do, however, continue to recommend replacement of all electrolytic capacitors
    in the unit before applying power to the unit. The reason being that, since the
    unit has likely been out of service for many years, the electrolytics are likely
    dried out, and are likely to exhibit extreme leakage when powered up. This can
    destroy a quite expensive power transformer in short order. It's much cheaper
    to replace these capacitors than risk damaging or destroying the single most
    expensive component in the set.
    Paper capacitors easily absorb moisture and become leaky. They might not take
    out the power transformer, but can lead to hours of troubleshooting frustration.
    There's a high probability that the paper capacitors will soon fail, even if
    they don't exhibit any immediate problems.
    Resistors are a bit different, but they do change value. Moisture absorption is
    a culprit there as well. Again, it's easy to check resistors in a tube set, and
    they should be replaced as necessary.

    Cheers!!!!
    --
    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
    address)

    "In theory, there isn't any difference between theory and practice. In
    practice, there is." - Yogi Berra
     
  13. Bill Jeffrey

    Bill Jeffrey Guest

    You would do well to repost this query in rec.antiques.radio+phono.

    Bill Jeffrey
     
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