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"Bride of Frankenstein" CD4 Demodulator

Joined
Dec 20, 2014
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As the development of an integrated circuit CD4 solution hit it's pentacle with the CD4-392, quad died before very many manufacturers implemented the IC. The most notable are the Sansui QRX 8001/9001 and Fisher/Sears 634. I have not found a mainstream separate demodulator except maybe the CD4-50 and the Grundig GRUN-03660 (and those units are not exactly mainstream). I can't verify that the CD4-50 has the IC, even though I have the schematic, I don't have the schematic of the sub-assembly TDM-27 which would contain that part of the circuits.

So, here's what I did: I have a Pioneer QD240 that is on it's death bed and a Fisher 634 that cosmetically is beyond restoration. So in the tradition of Frankenstein, I did a transplantation of the Fisher's CD4 demod into the Pioneer. I had to make a few adjustments of course. I have not yet generated a top assembly interconnect diagram, but the schematics of the Fisher and Pioneer are readily available. I have attached a few drawings and a Postimage link: http://postimg.org/gallery/194hxmdps/

I am in the debug stage. It works well but I have a minor ground loop issue to clean up.

And yes, there is a "Frankenstein" demod in the works, it addresses the flaw of the CD4-392. Maybe I will go ahead and post soon the prelimary efforts.
 

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Joined
Dec 20, 2014
Messages
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A couple of updated info. I have verified from pictures sent to me that the CD4-50 uses the IC CD4-392s. Also I have learned that the Akai AS-1070, 1080 and 1080DB uses the CD4-392 IC.