Quick Fisher 500-B Question re: MPX Decoder

Discussion in 'Fisher' started by mrphilco, Jan 19, 2019.

  1. mrphilco

    mrphilco AK Subscriber Subscriber

    Messages:
    473
    Location:
    Ferdinand, IN
    Correct me if I'm wrong...shouldn't the 500-B have a WX MPX decoder and not an MPX-65?
     

     

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  2. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    22,205
    Location:
    Glen Burnie Md.
    It should have the WX. But having said that, if it's a high serial # unit, then a possibility exists it may have a MPX-65. OR someone prior to you swapped in a MPX-65.
     
  3. mrphilco

    mrphilco AK Subscriber Subscriber

    Messages:
    473
    Location:
    Ferdinand, IN
    I'll check the S/N later and report back. This is a unit I bought last year and was thinking about giving it a good going over in the near future. As found, it is working but not in FM Stereo - FM is only in Living Mono.

    Thanks Larry - and congratulations on your engagement!
     
  4. visman

    visman AK Subscriber Subscriber

    Messages:
    1,001
    Location:
    Mid-Coast, Maine
    FYI - my 500B does have the WX with what looks like serial # 24146E

    Ditto on the congrats!
     
  5. 1rebmem

    1rebmem AK Subscriber Subscriber

    Messages:
    175
    Location:
    Wilmington, NC
    My 500B has the WX. It does not show signs of replacement, based on the under side.
    It was made in 1965.

    Jef
     
  6. mrphilco

    mrphilco AK Subscriber Subscriber

    Messages:
    473
    Location:
    Ferdinand, IN
    Ok. S/N 35108N and it does have a WX MPX decoder. Guess I confused my 500-B with my 400. Oops. I blame the chemotherapy regimen I'm currently on (it really does interfere with one's thinking). :confused::oops::crazy: Thanks to all.
     

     

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  7. bhamham

    bhamham AK Subscriber Subscriber

    Messages:
    2,077
    Location:
    Austin
    Mine is a 33455 s/n with the WX.

    The only schematic/service manual I can find on Fisher Consoles is for those up to 29999. Anyone know you can get the later one?

    Hope the chemotherapy goes well, Ron.
     
  8. mrphilco

    mrphilco AK Subscriber Subscriber

    Messages:
    473
    Location:
    Ferdinand, IN
    Thanks, much appreciated. Good question you raise, as I will also need a later service manual when I dig into this receiver.
     
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  9. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    9,900
    Location:
    Ball Ground, GA
    Ron -- The 500B does in fact use the WX decoder (which operates the composite and matrix stages from a lower B+ level than the MPX-65 version does), but they all employ the same basic circuit, with the alignment process for any of the Fisher 3 tube decoders being identical.

    Good luck with your 500B -- and your therapy!

    Dave
     
  10. mrphilco

    mrphilco AK Subscriber Subscriber

    Messages:
    473
    Location:
    Ferdinand, IN
    Thanks Dave for chiming in and for your kind words, I do sincerely appreciate it.
     
  11. audmod01

    audmod01 Super Member

    Messages:
    1,382
    Location:
    Tioga, TX
    Ron;

    Remember that 1uF coupling cap in the MPX decoder. After so many years it is probably open or nearly so. In my 800-C replacing that part restored full FM stereo.

    I was reluctant to say anything here about your cancer therapy. Prayers and best wishes in this new year!

    Joe
     

     

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  12. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    37,732
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    Cheers Ron, best wishes to you
     
  13. Dave451

    Dave451 AK Subscriber Subscriber

    Messages:
    1,297
    Location:
    Philly area
    Ron,
    Hang in there and best wishes for your treatment and recovery.
     
  14. mrphilco

    mrphilco AK Subscriber Subscriber

    Messages:
    473
    Location:
    Ferdinand, IN
    Thanks to all of you. I think that I'll get started in earnest on this 500-B once I do some more fiddling around and (hopefully) finish up a Marantz 4230 that's been on the shelf for awhile after its tuner died. I've already bought a matched quad of Tung-Sol 7591A tubes for it - it currently has two Electro-Harmonix and two JJ 7591 tubes, which range from fair to poor in my tube tester.
     

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