Fisher 202T Help

dcgillespie

Fisher SA-100 Clone
Subscriber
Looking to source the collective mind of the Fisher forum regarding what the intended MPX unit was that was to be retrofitted into this unit when MPX decoders were made available by Fisher for these units. It has a chassis cut out for the decoder (similar in size to an MPX-65), and a 9 pin socket for connection to it. For those not familiar with this unit, it's from the brass face plate era, when AM/FM stereo was the only mode of stereo broadcast available, before MPX transmissions were approved, but obviously had provisions on board for that eventuality. It includes full preamp facilities largely taken from the 400C preamp design, and is also known as the "Statesman".

Also wondering if the schematic for this unknown MPX unit -- if that unit can be determined -- is available.

I have a 202T here that I am going to install an MPX-65 unit in, but it is clearly not the originally intended decoder for this unit. It would be helpful to know how the connections from the 202T were originally intended to be made, and a schematic of the proper decoder would aid in that effort.

Finally, how in the heck did Fisher ever intend to announce reception of FM Stereo MPX broadcasts (when received) on this unit once the decoder was installed? That would appear to be a conundrum for sure, although I have an idea that might work.

Thanks in advance for any and all help provided!

Dave
 
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Dave; The MPX 20 was intended for the 202-t and a couple of others. But it was for the Crosby MPX circuit. See the sticky FISHER MPX Adapters. Not a lot of infor on these. http://www.audiokarma.org/forums/showthread.php?t=412418

There should be a 9 pin plug (female) that the 20 plugs into. The RCA jack would probably plug into the mpx out plug.
 
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Larry -- that makes perfect sense based on the connections provided in the 202T for the MPX adaptor, and coincides with the information provided with the unit (that the MPX-20 was the intended decoder). Was there ever a schematic available for that decoder?

Dave
 
Not that I've ever seen. You might ask Carter (PM THERED1), he may have something on it.
 
There's a SAM's Photofact on Ebay for the MPX 20 for $5.00

Ebay number 320450452939
 
That one's in Public Domain now?

Sorry Tom; It didn't occur to me that you might have it. I thought Sams might still have Copyright or whatever they are claiming on that one.
 
Dave:I have a schematic too that I found on the web....has picture of the mpx20 in the body of the one page schematic. If you need that PM me and I will send...not sure where it came from but was out in the public domain...
 
Thanks Glen -- Tom came through as he always does, so I've gotten the information I needed. This is one of those reverse engineering projects of trying to make an MPX-65 decoder work where the MPX-20 was designed to. The basic installation is not that big a deal, but the signal application to the decoder is different for the 20 than the 65, which I could see by the facilities provided for the 20's installation. But I also wanted to see what was then happening in the decoder as well, as that determines how effectively I can make the 65 mate with the features of the host unit it is going in, and not just merely work after a fashion. There's always a huge divide between "works", and works properly!

Dave
 
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