Quick Fisher 500-B Question re: MPX Decoder

mrphilco

AK Subscriber
Subscriber
Correct me if I'm wrong...shouldn't the 500-B have a WX MPX decoder and not an MPX-65?
 
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.
 
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!
 
FYI - my 500B does have the WX with what looks like serial # 24146E

Ditto on the congrats!
 
My 500B has the WX. It does not show signs of replacement, based on the under side.
It was made in 1965.

Jef
 
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.
 
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.
 
Thanks, much appreciated. Good question you raise, as I will also need a later service manual when I dig into this receiver.
 
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
 
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
 
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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