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-   -   silver mica disease in dicriminator transformer (http://www.videokarma.org/showthread.php?t=263084)

Paul Knaack 11-26-2014 11:00 AM

silver mica disease in dicriminator transformer
 
Would anyone know what the value of the internal silver mica capacitors across the coils of the sound discriminator transformer?
For a Zenith 28T960.
Its coil L26, 21.3 mc part no. 95-1120. Thanks

http://www.earlytelevision.org/pdf/Z...Sams-64-15.pdf

wa2ise 11-26-2014 12:01 PM

If you can't find this out, you might be able to disassemble the transformer and get at the mica wafer. Don't know about their TV sets, but in Zenith radios of this vintage the wafer was under a phenolic wafer (holds the terminals) and fastened by a nut on a screw. Once I removed it, I took a sharp knife and scribed the areas between the silver areas. That would break the silver migration paths. I then put it back together and it worked better.

Paul Knaack 11-26-2014 12:42 PM

Sounds like the same construction. But I already destroyed the mica wafer with the silver on it.
I was playing with it and took a can of canned air and blew it between the phonolic wafers while waching plate voltage of the limiter tube. The voltage came up from 12 volts to 25 volts (should be 45 volts). So I gave it another blast and this time the mica wafer blew out of it in tiny peices.
What a dumb thing to do!

Paul Knaack 11-26-2014 05:00 PM

I think I found it, I took the transformer out and took it apart and measured the caps with my cap tester and seems to test real close to the 95-1153. Only one section of what I believe to be a 24pf section was missing. gimf
http://www.sparkbench.com/zenithifxfmrs.gif


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