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My Dad's old valve radio

Discussion in 'Electronic Repair' started by Macthesage, Feb 2, 2005.

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  1. Macthesage

    Macthesage Guest

    Dear Radio Experts,

    This is a bit of a shot in the dark for me. I would like to fix the
    old valve radio which has knocked around in my family for decades and I
    left it in to the local electronics repair shop about 18 months ago.
    Good news is they still have it. Bad news is that nothing has been
    attempted to get it going again.

    Some questions for you all:

    Given its age at about 50 years what is most likely wrong (it last
    worked in 1990)?
    Where can you get repair parts?

    In fairness to the repair guy, he did mention that replacement valves
    are difficult to source but how difficult is difficult?
    Thanks for any help.
     
  2. Lou

    Lou Guest

    Not saying you won't get some good answers here, there is much to be had....
    but some other groups you may want to visit are the news groups of -
    rec.radio.amateur.boatanchors (if a Short wave style) -AND/OR-
    rec.antiques.radio+phono - this group sort of covers both the short wave
    and family style radios.

    There are some tubes(valves) floating around - a list would be a good start.
    Knowing the make and model of the radio in question would help others to
    help you. There are also some shops here in US - not sure where you are,
    that do specialize in antique radio repair - down to cabinet restoration.
    Some have trouble locating such things as "Dial String" which is used in
    those radios... There are folks in the latter news group who do sell it.
    Perhaps not exactly as used, but a good substitute.
    Chances are, maybe some of those folks can help you out. I'm not into boat
    anchors myself, but if I were - from what I've seen there - I would look to
    them for their expertise. I've learned a lot from the posts I have read
    there. It's amazing to hear what some of those guys have done with some
    rather dilapidated cabinets, chassis, and so on. Helping to preserve
    history.

    L.
     
  3. Gary J. Tait

    Gary J. Tait Guest

    Most likely condensers.
    Older TV shops, or specialty companies in the antique radio refurb
    buisness.
     
  4. majortom

    majortom Guest

    Don't give up..
    As others have said, there are plenty of resources available, just have
    to look around.
    Having restored an old WWII era Zenith myself,

    Here's what I would do...

    Note the Make, model number, even serial number.

    1. Don't power it up yet, dried up electolytics capacitors tend not to
    take too kindly after sitting for so long.
    2. Go to your local library, a main downtown branch is the best
    resource.
    They can help you locate the schematic diagram for it (somewhere in the
    technology section). You may even find one pasted inside the chassis of
    yours.

    3. With Schematic in hand now, find someone local who has access to an
    old tube tester.
    Call around to various TV Repair shops, someone has to have one laying
    around somewhere. Use this resource to test the condition of each and
    every tube in your radio.
    They can give you a recommendation on which ones might be toast, a
    little weak or in good shape.

    4. Based on 3, Look for any tubes you may need, search around the net,
    ebay included, and wait around till a local hamfest arrives in your
    town (springtime around my area). By this time you'll have a good idea
    what you need to look for and ya might just get lucky right there at
    the local hamfest.

    5. While your waiting to find any spare tubes you may need, try to
    locate the electrolytic capacitors in your chassis. They stand out as
    rather tall auminum can lookin things. These are what tend to dry up
    over the years and can cause grief, and have been known to just "POP"
    upon applying power for a while after sitting so long. It's probably
    best to just wholesale replace every one of these assuming you can find
    suitable replacements, which normally isn't too hard (again hamfest).
    If they aren't toast today, they will be shortly anyway.

    6. Now you may try to power the thing up again and see what happens. If
    it works well, fine. If not, there are other capacitors that some
    restoration folk will just replace as well. These would be any
    interstage coupling caps, bypass caps, etc. At this point is where the
    schematic helps a lot.

    7. Some restoration folk may even recommend re-wiring the whole thing
    as well
    depending on the vintage. In my case I went ahead and did that myself
    as well, being from
    WWII era it used really crummy wiring and insulation (copper was
    conserved for other obvious uses back then).

    Mine has this really cool speaker and sounds awesome, it uses an
    electromagnetic speaker. Modern speakers use a a permanent magnet for
    the voice coil to drive thru.
    It's a 1941 Zenith tabletop with mechanical pushbuttons for AM
    broadcast station presets. And does two bands of shortwave as well. Put
    a lot of time in restoring it, but it was a lot of fun.

    Good luck

    p.s. - I found it at a yard sale for 20 bux, offered 'em 10 and it was
    mine:)
     
  5. Jim Adney

    Jim Adney Guest

    There's no doubt that this can be fixed.
    The most likely problem is a bad electrolytic capacitor.
    You have to get in contact with the right people. The antique radio
    newsgroup is the place to ask.
    They are not difficult to find at all. You just have to ask the right
    people. They will be hard to find in one of today's normal electronic
    repair shops. Many of the people there may never have even seen a
    vacuum tube, other than a CRT.

    -
     
  6. Guest

    Hi,
    I did some research for a client who had an old radio. Turns out some
    of these are quite collectable. These are American. Here's some URLs:

    http://antiqueradios.com/
    http://antiqueradio.org/faq4.htm
    http://antiqueradio.org/parts.htm
    http://www.geocities.com/CapeCanaveral/9178/radios/12ba7.html
    http://www.geocities.com/CapeCanaveral/9178/
    http://www.tubesandmore.com/

    Take care most of these have hot chassis, talked about in these groups.
    You didn't specify but seems like yours is English? Try Googleing the
    specific make. I'd bet there's whole groups out there specializing.
    Richard
     
  7. NSM

    NSM Guest

    What exactly happens when you plug it in? Any sounds? Any lights?

    I assume you're in Eire?
     
  8. NSM

    NSM Guest

    Last one I fixed had a bad dropping resistor across the multi section filter
    capacitor. I diagnosed it in 3 minutes with a screwdriver and a pair of
    needle nosed pliers.
     
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