It looks like I have an open field coil (primaries) on my Zenith 5S338. what should be my next step? I am not sure about this, so what can I do to verify this,...
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NORMAN LEAL
normrleal
Dec 2, 2007 4:12 am
Hi Bill Measure resistance of the field. It should be around 2125 ohms. See schematic: http://www.nostalgiaair.org/PagesByModel/011/M0025011.pdf You can...
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John E. Beech
johng8seq
Dec 2, 2007 8:10 am
Hi Bill, Using a PM speaker is not the best option. Usually these type of speakers were used for "Hum-bucking" . The field coil has to be wired the correct way...
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John E. Beech
johng8seq
Dec 2, 2007 8:15 am
I'm confused! The circuit diagram on the web page ( below) shows a "normal" o/p transformer and permanent magnet speaker. Is your model radio ie. speaker...
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John E. Beech
johng8seq
Dec 2, 2007 8:29 am
Hi Bill Norman, et al. Ignore my last e-mail. It would help if I could read!. I've just found the speaker field coil on the schematic, connected in the PSU...
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Bill Harms
philcobill
Dec 2, 2007 1:00 pm
Okay, to make sure we are all talking about the same things here, mostly for my benefit, this is what I have. ...
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Bill Harms
philcobill
Dec 2, 2007 1:15 pm
Before I get the speaker rewound, please walk through this with me so that I am clear about what is going on. Also, if I decide to have the speaker rewound, is...
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John E. Beech
johng8seq
Dec 2, 2007 1:24 pm
Hi Bill, My comments in capitals to distinguish from what you wrote. de John G8SEQ....
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Bill Harms
philcobill
Dec 2, 2007 1:40 pm
Thanks John, Okay, so just checking for my edification, if the resistance across the leads for the output transformer is infinite, which it is, then I need to...
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Jon Scaptura
scap0133
Dec 2, 2007 1:46 pm
You have it backwards. The field coil is the coil directly behind the speaker cone. It serves as the magnet for the speaker. The smaller transformer is the...
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Bill Harms
philcobill
Dec 2, 2007 1:50 pm
Okay thanks Jon. That makes sense. I saw you 38-3. I have one also. It is a very handsome piece. Bill ... -- Bill Harms Elkridge, Maryland Check out the...
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John E. Beech
johng8seq
Dec 2, 2007 2:10 pm
Hi Bill, Yes the coil resistance of the primary of the transformer should be a few thousand ohms, depending on the power of the stage. The ouput side will be...
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Bill Harms
philcobill
Dec 2, 2007 2:28 pm
John, this helps. Now the next step, figuring out what to do. Based on past experience, finding the correct values for the output transformer can be...
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NORMAN LEAL
normrleal
Dec 2, 2007 6:10 pm
Notice below in the power supply the choke says "field coil". Agree it looks like a PM speaker but field is drawn below. Norm "John E. Beech"...
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Bill Harms
philcobill
Dec 2, 2007 6:28 pm
Thanks to all for your help. I think I have decided to simply replace the audio output transformer. I have an Antique Electronic Supply catalog in front of me...
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Peter Hadgraft
peterhadgraft
Dec 2, 2007 10:13 pm
Field coil and hum-bucking coil are not the same thing. The field coil is driven from the PSU. In some old sets it was a separate circuit from the radio ie it ...
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Bill Harms
philcobill
Dec 2, 2007 10:31 pm
Thanks Peter, Okay, then what do I have here in the URLs below....
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John E. Beech
johng8seq
Dec 2, 2007 10:47 pm
Hi Peter, You are right. The humbucking coil is an additional coil to the field coil. I just googled humbucking to check. It is a long time since I have seen...
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Bill Harms
philcobill
Dec 3, 2007 12:08 am
I found an audio output transformer at Antique Electronics which would physically fit the best in my Zenith 5S338 but it is a Push-pull type. In the catalog...
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Peter Hadgraft
peterhadgraft
Dec 3, 2007 8:06 am
Bill, Use the whole of the primary winding, leaving the centre-tap disconnected, that could work fine, or use half of the primary and leave the other half ...
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Bill Harms
philcobill
Dec 3, 2007 10:56 pm
How liberal can one be about finding a suitable substitution for a selenium rectifier? I have a Philco 46-350 which has one and I need to replace it. I ...
355
NORMAN LEAL
normrleal
Dec 3, 2007 11:30 pm
Bill Use a 1N4007, even 4005 or 4006 will be ok. Add a 47 ohm resistor in series with the diode when you replace the selenium rectifier. You can adjust the...
356
John E. Beech
johng8seq
Dec 4, 2007 8:12 am
Hi Bill, A single 1N4006 rectifier diode would replace that, if it is a half wave rectifier or two if it is fullwave with centre tapped transformer. They are...
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Bill Harms
philcobill
Dec 6, 2007 9:48 pm
My Zenith 5S338 has rust on the dial face. Please refer to the following URL http://www.philcobill.com/gallery2/v/zenith/zenith_5S338/100_1708.JPG.html I am...
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Alex Whitaker
ehscott36
Dec 7, 2007 2:18 pm
Bill, I read of this solution in a book dedicated to collecting beer cans. I guess you can soak painted things that are rusty (like your dial...or an old beer...
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John Culp
slidepicker
Dec 7, 2007 8:20 pm
One more idea about output transformers: Small power transformers often have appropriate turns ratios for the desired output impedance. I've used them in ...
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alainfontaine2001
alainfontain...
Dec 8, 2007 2:08 am
Does anyone have a good method for easily stripping out old paint on a plastic radio without damaging the plastic? Thanks, Alain...
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Steve B
steveb94044
Dec 8, 2007 2:43 am
Hey Bill, Try using a pink pencil eraser. Sometimes you can remove some rust and not harm the dial surface that way. It's kind of like cleaning electronic...
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Roger Horton
k8cix
Dec 8, 2007 3:50 am
... a ... Alain, Are you sure it is plastic and not Bakelite? If it is Bakelite you can use regular paint stripper. If truly plastic experiment using ...
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radioman88@...
billsradios
Dec 8, 2007 4:18 am
Easy Off oven cleaner. Never used it myself but a friend of mine told me years ago that it did a great job of removing paint without damaging the radio. Bill ...
