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 Post subject: Re: Sparton 15 restoration
PostPosted: Jun Mon 19, 2017 12:00 pm 
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Location: Annapolis, MD
Expanding foam: no reason to believe it would be conductive, but I'll check. When drying, it shows no sign of attacking anything else. Once dry, it is inert.

I don't have a big database on pot cleaning....only two basic observations:
WD40 does not fix all bad ones, but has never damaged one
I tried IPA only once or twice on older pots. When one got damaged, I never used it again

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jun Mon 19, 2017 5:57 pm 
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I've rarely had isopropyl alcohol attack anything, though I left an old toothbrush in a jar with alcohol in it over the weekend. It did mess up the toothbrush head after 48 hours of soaking in the stuff. Never thought that would happen!

Everyone has their preference for cleaning old pots. Use whatever works best for you.

Kinda doubt the expanding foam is conductive, or would attack the outside of the encapsulated capacitors. Never hurts to check. Actually, I like your idea of using it. You may be one of the first restorers to try that technique.

Keep up the good work Mark.
Mitch


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 Post subject: Re: Sparton 15 restoration
PostPosted: Jun Mon 19, 2017 7:00 pm 
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Location: Capon Bridge, WV
IPA isopropyl alcohol.

I was wondering why you were using beer to clean a volume pot :wink: :lol: .

Outstanding work on that chassis.

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jun Mon 19, 2017 7:59 pm 
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Joined: Dec Wed 02, 2015 9:42 pm
Posts: 72
Location: Santa Clara, CA 95051
I have friends from India, they beautiful people and I feel fortunate to know them. But I've told them I do not like Indian food, sorry. And IPA, Indian Pale Ale, is not my favorite either. I'm a Guinness Extra Stout drinker.
:)

Just to be certain I'm on the same page with you, the re-stuffing is basically cosmetic? The old cans could have been left disconnected but attached to the chassis and the new caps placed elsewhere if there was room to do that?

Notice the question marks, because I'm interested in learning here if there is another electronic reason for doing that.

Your restoration looks awesome BTW. I hope it is a good receiver and sounds good when fired up.


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 Post subject: Re: Sparton 15 restoration
PostPosted: Jun Tue 20, 2017 1:15 am 
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I do not spend significant time on cosmetics under the chassis. In the case of the capacitor modules, I re-stuff them with the actual capacitors---mostly to preserve the wiring layout---and, in the case of radios like this one, because that's where the real estate is. This particular set is very cramped---look at the pictures and try to imagine how to get to the various tube pins for trouble-shooting.....:)

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Thu 20, 2017 2:44 am 
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Location: Annapolis, MD
Chapter XX--the speaker

It all begins innocently--the speaker has an open field coil. The good news---it comes apart with nuts and bolts. Here the coil, bell, and armature have been removed revealing the intermediate plate and humbuck coil.
Attachment:
spkr_humbuck.jpg
spkr_humbuck.jpg [ 42.98 KiB | Viewed 480 times ]

When we see the corrosion, no more thoughts of just "fixing it".
Attachment:
FC_old.jpg
FC_old.jpg [ 61.39 KiB | Viewed 480 times ]

Starting to patch the cone. Note the unique construction, with the cone captured by a ring that is riveted to the basket. I really do not want to take this apart, and so I commit to the RandR of the field coil with the cone in place.
Attachment:
spkr_glue.jpg
spkr_glue.jpg [ 59.46 KiB | Viewed 480 times ]

Bobbin on the winder (it is from a roll of solder, but shortened. the spacers are the cores from 3M magic tape---SAVE EVERYTHING!!)
Attachment:
bobbin_ready.jpg
bobbin_ready.jpg [ 58.93 KiB | Viewed 480 times ]

Speaker parts ready to go. The humbuck coil is glued to the intermediate plate to make assembly easier.
Attachment:
spkr-parts_ready-to-assemble.jpg
spkr-parts_ready-to-assemble.jpg [ 66.33 KiB | Viewed 480 times ]

"The Kludge"--this fixture holds the intermediate plate centered while the coil and bell are being installed. The drill is to first center the intermediate plate to the VC, then install the field coil and armature / bell. The intermediate plate is centered using a feeler gauge, then the kludge holds it in place. For the last step, we use a feeler gauge from the front.
Attachment:
the-kludge.jpg
the-kludge.jpg [ 48.99 KiB | Viewed 480 times ]


Done!!---and the VC doesn't rub!
Attachment:
spkr_done.jpg
spkr_done.jpg [ 65.6 KiB | Viewed 480 times ]

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Thu 20, 2017 4:21 am 
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Location: Capon Bridge, WV
Ahhhh in depth speaker repair. A labor of love.

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Fri 21, 2017 12:34 am 
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Location: Mission Viejo, southern California
Good job!

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Fri 21, 2017 1:50 pm 
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Location: Minneapolis, MN - USA
You guys never cease to amaze me.

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Fri 21, 2017 2:05 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: England
I have never had a speaker apart where the under plate wasn't fixed in place so never had to worry about that. A neat solution to holding it central in this case Mark, thanks ...

Gary


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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 1:27 am 
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Location: Dayton Ohio
Nice work, Mark!

Looks like there are more than just one speaker where removing the field coil causes problems with getting pole pieces in alignment. let alone getting voice coils centered.

This speaker from a Zenith 103 was a real bear, but I fabricated an alignment tool to get it right. I believe this speaker was manufactured by Wright-Decoster of St. Paul Minnesota.

http://www.theradiofox.com/zenith/zenith103/index.html

-Steve

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 1:30 am 
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The challenge with all the custom fixtures, widgets, etc. is to
--remember what they were for
--build them to be useful for more than one thing
--avoid the temptation to harvest parts from them
etc.

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 1:53 am 
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Location: Dayton Ohio
--or remembering where you put it when you need it again… Arrgh…

-Steve

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-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 2:45 am 
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Location: Minneapolis, MN - USA
azenithnut wrote:
I believe this speaker was manufactured by Wright-Decoster of St. Paul Minnesota.


A accurate observation on the side - St. Paul is nothing more than a DUMP in the State of MN these days, so don't go thinking that history of 100 years ago simply continues to apply to this day - far from it. You can give it the name of Dayton's St. Paul Sh%# hole these days.

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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 9:08 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2373
Location: England
"The challenge with all the custom fixtures, widgets, etc. is to
--remember what they were for
--build them to be useful for more than one thing
--avoid the temptation to harvest parts from them
etc."

I adapt chassis mounts Mark but do write on them, with a marker pen, what they were used for and what they do now. Sometimes there are 3 radio makes and models on them. Actually, although I should be able to go back to what they were used for its rare that I do the same chassis again.

Gary


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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 1:14 pm 
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Nortonics wrote:
azenithnut wrote:
I believe this speaker was manufactured by Wright-Decoster of St. Paul Minnesota.


A accurate observation on the side - St. Paul is nothing more than a DUMP in the State of MN these days, so don't go thinking that history of 100 years ago simply continues to apply to this day - far from it. You can give it the name of Dayton's St. Paul Sh%# hole these days.


That is sad to hear considering it is the state capital…

-Steve

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-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Sparton 15 restoration
PostPosted: Jul Sun 23, 2017 1:39 pm 
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The more you hijack my thread, the more I am motivated to finish the set.....;)

I LIKED St Paul. Among other things, it is Garrison Keilor's home base.

What exactly is the problem?

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