Sherwood S-3000 III Help

Discussion in 'Tuners' started by valco, Oct 10, 2017.

  1. valco

    valco New Member

    Messages:
    17
    So I acquired this tuner. I've got it hooked up. Everything seems to work except I'm getting a loud oscillation that changes pitch when I turn the tuning knob. Any ideas on what this could be and how to fix it?
     
  2. valco

    valco New Member

    Messages:
    17
    Ah, well, I seemed to have worked it out. All is working now.
     
  3. valco

    valco New Member

    Messages:
    17
    Yikes, okay, sorry for the back and forth. Seems the oscillation is still there. There are just a few spots I can tune to where there is no oscillation, but most of the sweep still has the steady singing oscillation on top of the radio signal. Again, the pitch seems to raise and lower as I move the tuning knob. When I tune to the few spots where the oscillation disappears, it sounds really nice and full.

    Any ideas what this may be?
     
  4. Punker X

    Punker X AK Subscriber Subscriber

    Messages:
    3,883
    Location:
    Panic in Detroit
    MPX unit? Mis-aligned MPX would be my first guess, possibly a weak tube in the MPX.
     
  5. 39cross

    39cross AK Subscriber Subscriber

    Messages:
    894
    Location:
    Beverly, MA
    To follow up on Punker X's comment, these have an optional MPX unit, does yours have it? If you're not sure you can post a photo.

    Something easy to try: the tube pins can sometimes get oxidized, remove the tubes, clean the sockets and pins with deoxit if you have it. Sometimes wiggling a tube in the socket might reveal a bad connection. Might have nothing to do with your problem, but it's something to check.
     
  6. valco

    valco New Member

    Messages:
    17
    Thanks for your replies! That did it! I cleaned up all the sockets and now its nice and clear. Working beautifully. Thank you all!

    Also, no, this is not an MPX unit. It has a marking on the chassis that says MPX but there is nothing there. I heard you can add a stereo option to this. Whats the easiest way to do that?
     
  7. 39cross

    39cross AK Subscriber Subscriber

    Messages:
    894
    Location:
    Beverly, MA
    The 'III' doesn't have an MPX RCA jack, so it's more complicated than attaching an outboard MPX adapter. People have figured out a way to do, but they are at a higher skill level than I am. Maybe I saw this on the FM tuners board. A search should turn something up.
     
  8. KiM3Ce

    KiM3Ce AK Subscriber Subscriber

    Messages:
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    Location:
    Arizona
    Welcome! Please post some photos; that will help us give you guidance.

    There are many flavors of the Sherwood 3000-III. If there is a jack on the back that says "Multiplex", that can be connected to an external decoder. If there is a removable plate on the rear of the chassis, Sherwood made a drop-in decoder that would fit there. You can also build one based on the 4500 chip; see http://fmmpx.com/. Many companies made tube decoders back in the day but they are rare and pricey now.
     
  9. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    32,865
    Location:
    Southern NJ
    The S3MX is the usual external unit. Not sure what the internal one was.

    If you're not opposed to solid state you might find someone parting out a reciever from the 70s that had a stand-alone FM board. I have one out of a Pioneer SX-990 that just needs 12 volts and signal input to make it all go. Its a bit DIY but overall works pretty well.
     
  10. 39cross

    39cross AK Subscriber Subscriber

    Messages:
    894
    Location:
    Beverly, MA
    Here is a photo link I found that shows the S3000-III MPX board and plug. The plug-in board is hard to find, probably not many were made as this was in the brief interim before the S3000-IV and its successors, which had built-in MPX after the FCC came up with the stereo broadcast standards.[​IMG]
     

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