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Hi guys,
I've run into a wall with this radio. All caps have been replaced. All resistors, coils and tubes have been tested and replaced as nec. I am able to do a complete alignment, but I have no FM reception at all  , not even static. AM works great!
What do you think?
Thanks,
Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
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Hmmm...
Can you try injecting an FM IF signal along the FM IF path and see where it appears (or disappears)?
--
Ron Ramirez
Ferdinand IN
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Sounds good. I'll check it out and get back to you.
Thanks, Ron.
Eric
The Villages, FL
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I have no FM reception at all [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif] , not even static.
Funny thing about that's how FM works No Static!!!
Your a glutton for punishment!!!
If you don't a Fm generator you can use an am signal
but use a tracer with a RF probe (diode detector) to follow
the signal around till you get to the limiter stage.
GL
Terry
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OK, it appears that the signal goes in to the 1st IF trans and doesn't come out. It feels like the core is binding when I try turn it. Could the trans be bad? BTW, I have an exact replacement.
Thanks,
Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
(This post was last modified: 05-12-2015, 05:02 PM by Eric Adams.)
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Possible but I'd measure the resistance across TC-6 Should have a very low resistance. I have had cores seize to the coil form and while trying to adj it has ripped the wires right off the coil render it useless.
Terry
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The resistance was very low and matched with the spare that I have. Any other ideas?
Eric
The Villages, FL
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(05-12-2015, 06:29 PM)Eric Adams Wrote: The resistance was very low and matched with the spare that I have. Any other ideas?
Well I think I'd just swap it out. Could have a bad cap across the winding. Only 4 wires not a big deal.
Terry
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Thanks. I'll give it a shot.
Eric
The Villages, FL
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OK, I replaced both 1st and 2nd IF transformers  No luck.
Any other ideas?
Eric
The Villages, FL
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Soooo where are you losing signal now?? Is it making it though the 2nd IF stage??
Terry
(This post was last modified: 05-19-2015, 09:24 PM by Radioroslyn.)
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I was too frustrated to check. I'll check it tomorrow and let you know.
Eric
The Villages, FL
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I find FM stuff frustrating too!!!
Terry
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Keep on plugging at it. You have my sincere sympathy; I restored a 48-482. Double and triple check all your connections. You'd be surprised how easy it is to look at something and see it as right one time, only to pick it up on a second look closely following the diagrams that show parts locations and wiring, and the schematic. Don't get frustrated. One thing about these old radios, when they don't work, something IS wrong. You'll find it eventually.
Posts: 825
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Thanks mike. I know what you mean. I have restored two 48-482s and had less trouble. The set of schematics and pages of troubleshooting that is available for the 48-482 is fantastic and really helps with diagnosis. The 50-925 doesn't come close with their poor documentation.
I haven't given up yet but it is being punished for a while. It will sit on the shelf until I feel better about it.
Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
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