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#1
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Accidentally hit a choke coil with my soldering iron… how screwed am I?
*sigh* Of course, the last capacitor I needed to replace on my first repair I’ve been working so hard on, I accidentally singed one of the coils connected to pin 6 of a 6T8 socket in my Stewart Warner TV. According to the schematics, it’s the choke coil rated at 15 ohms. It looks pretty burned/black sadly… I believe these coils NEED insulation so… I’m curious if rewinding this is even doable knowing how thin the wiring is. Any ideas how to fix this possibly?
Photo of the coil pre-fry and repair below: |
#2
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I can also provide a photo of the damages if needed.
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#3
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Quote:
there is often listings under miller / merit / meissner and others on the list. most of which can still be found on evil-bay for fair prices. winding your own will be next to impossible w/o the correct rig to do so. The SAMS should have all the info to find a replacement, including the microhenry rating and resistance and if its wound on a resistor.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#4
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I have, and there are no replacements listed in the table. There’s columns for Meissner and IRC, but none specifically are listed for this coil. Microhenry rating is also not specified in the SAMS or the service manual. |
#5
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does it still test at 15 ohms?
not sure if this is the right SAMS but it says https://www.earlytelevision.org/pdf/...sams_64-12.pdf l34 rf choke 507373 15 ohms SOMEONE may be able to look it up in an old cross ref book.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
Audiokarma |
#6
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Quote:
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#7
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This is what I get for being a bit panicky… looking silly. But at least I know I don’t have to begin a possibly endless hunt for a new coil. Thank you. |
#8
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https://www.amazon.com/MG-Chemicals-...008OA7CAE?th=1 it's not cheap, but does the job. in a real pinch, clear nail polish may work, but corona dope is much better for protecting the coil in the long run.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#9
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Has anyone thought what that portion of the circuit is doing? It looks weird to me.
It looks like a feeble attempt at providing further AM limiting. The plate of the limiter is capacitively coupled to the 19T8 diode plate. The choke coil is simply an RF choke to preventing the sound IF being bypassed fully to ground. It looks as if this is an attempt to further IF limit any residual AM reached the sound detector. I am especially curious the placement of the 10uF electrolytic: the IF rectification of the diode should place a negative voltage on the diode plate corresponding to the peak negative excursion of the IF signal. This means the 10uF capacitor is reverse polarized. Makes me think that it would work better if that coil was open! |
#10
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Quote:
Last edited by Madeline12; 05-02-2024 at 05:27 PM. |
Audiokarma |
#11
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... same as the Sams posted except that the electrolytic is backwards.
It looks as if it is another example of Sams making an error! Sams, especially on the early drawings,makes lots of mistakes. Last edited by Penthode; 05-02-2024 at 07:03 PM. |
#12
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also, if this is the right SAMS, this set seems to be series strung, and has a 19t8, is that correct?
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#13
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It is presumably 4.5 MHZ. Go to Mouser, look at Inductors, search Miller or Bournes, axial lead.
Pretty much any of the little series lead ones with a 75 to 200 uH value and a self resonant frequency (SRF) greater than 12 MHz will work. |
#14
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Well, it seems that the original part is still viable, provided that it's kept safe from future corrosion and oxidation, thus I mentioned sealing it with enamel such as corona dope, cause if it indeed still good, once sealed, it should be good for another 30-40 years or more!
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
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