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City: Jasper Arkansas
confused on schematic, the if can before the 7c6 has 5 wires in it grn,blue,black,red and white. the black wire is center tapped in the secondary side of the transformer but nowhere on the schematic. at present i have connected it to pin 4 on the 7c6 but i do not think this is right. getting 455khz tone all the way to the primary side of the transformer but no further. the 50l6 is not producing anything thru a speaker but i can get something when using signal tracer.any ideas?
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City: Albuquerque, NM
(01-19-2015, 12:12 PM)mountain man Wrote: confused on schematic, the if can before the 7c6 has 5 wires in it grn,blue,black,red and white. the black wire is center tapped in the secondary side of the transformer but nowhere on the schematic. at present i have connected it to pin 4 on the 7c6 but i do not think this is right. getting 455khz tone all the way to the primary side of the transformer but no further. the 50l6 is not producing anything thru a speaker but i can get something when using signal tracer.any ideas?
There are three additional components inside this I.F. as shown on the schemo. 45A,C & D I believe. Anyways they are two 100pfd caps and a 47K resistor as shown below the 7C6 tube on the schematic. The black wire has to connect the two 100 pfd caps to the 7C6 cathode pin 7. Good luck. 
John
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City: Jasper Arkansas
Thanks John, I guess I need a refresher course in schematic interpretation, never noticed that but at 75,
I have a good excuse. going to replace all if can wiring as they are all cracked and some exposed so replacing caps are a must while I'm there.
Posts: 94
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Joined: May 2010
City: Albuquerque, NM
(01-19-2015, 06:26 PM)mountain man Wrote: Thanks John, I guess I need a refresher course in schematic interpretation, never noticed that but at 75, I have a good excuse. going to replace all if can wiring as they are all cracked and some exposed so replacing caps are a must while I'm there.
The first time I took a similar Philco IF apart to replace the rubber wires I thought - where are the 100pf caps?
The resistor was a common carbon comp. but I found the caps are built into the ceramic substrate and are not replaceable themselves. I measured with a LCR meter and indeed there was pf readings where the caps are to be located. I think these caps are supposed to shunt any extraneous RF to ground. The 47K in yours is actually in line with the AVC buss.
John
Posts: 24
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City: Jasper Arkansas
John, glad that You told me this as i found no caps in the if can in question, thought I was loosing it for sure but now I know. The 7c6 which follows the last if can is a little difficult to understand but the problem lies in that area, unfortunately someone was there before me so now my problem is even further aggravated. Ah the joys of radio repair especially for the novice. Thanks for your input, would be better if You lived next door
