Discussion:
LOL! First things first...
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o***@gmail.com
2017-06-11 13:54:04 UTC
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OK, I deserved this:

One of my customers (an older lady) was enamored by a very ordinary old Philco AM radio that was kicking around my shop. I thought she'd be thrilled to have this as a gift so over the next week in between jobs I slowly recapped it, put in a new AC cord, checked and replaced the couple of cranky loctals, cleaned, lubed, and reset a couple of shorting gang sections on the tuner. Sounds like crap; low power and distortion when the volume is advanced beyond one quarter.

Yep, frozen voice coil. I mean zero movement. I used some acetone to dissolve the adhesive holding the dust cap to remove it and it looks like the pole piece is slammed to one side pinning the VC to the frame.

This really stinks because the speaker frame assy also locates the dial assy in the radio. The good thing is that I didn't get to restoring the cabinet.

More evidence that no deed goes unpunished!

John

Wolcott, CT
o***@gmail.com
2017-06-12 15:09:21 UTC
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Post by o***@gmail.com
One of my customers (an older lady) was enamored by a very ordinary old Philco AM radio that was kicking around my shop. I thought she'd be thrilled to have this as a gift so over the next week in between jobs I slowly recapped it, put in a new AC cord, checked and replaced the couple of cranky loctals, cleaned, lubed, and reset a couple of shorting gang sections on the tuner. Sounds like crap; low power and distortion when the volume is advanced beyond one quarter.
Yep, frozen voice coil. I mean zero movement. I used some acetone to dissolve the adhesive holding the dust cap to remove it and it looks like the pole piece is slammed to one side pinning the VC to the frame.
This really stinks because the speaker frame assy also locates the dial assy in the radio. The good thing is that I didn't get to restoring the cabinet.
More evidence that no deed goes unpunished!
John
Wolcott, CT
As providence would have it, I actually have an exact speaker in the boneyard, but it's got two tears in it but fortunately also has a very free moving VC. So the good news is that my efforts in recapping this worthless radio were not in vain.

Without starting a war here, I am interested in hearing some favorite fixes for stabilizing torn speaker cones, particularly any newer methods.

I've seen some references to GC Service Cement and I thought I possessed a bottle, but what I actually have is some GC General Purpose Plastic Cement which has a different part number and is now discontinued. It also claims to remain a bit flexible as the Service Cement does.

I painted some old pulpy paper with this cement straight out of the bottle, then painted another sample with a 50/50 dilution of this same cement and acetone (to allow better absorption into the paper) then the final sample using the same diluted sample with thin paper painted into the sample paper.

The two diluted samples definitely flowed completely into the paper where the straight sample didn't seem to flow through.

After an hour, all three paper samples are eminently flexible (including the one with the reinforcing paper added), but I'm concerned about the long term prospects of this particular cement to become brittle over time.

Any insight appreciated.

John

Wolcott, CT
Foxs Mercantile
2017-06-12 15:26:02 UTC
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Post by o***@gmail.com
After an hour, all three paper samples are eminently
flexible (including the one with the reinforcing paper
added), but I'm concerned about the long term prospects
of this particular cement to become brittle over time.
I've had good luck using Lipton Tea bag paper to bridge
small holes and tears.
I was using Borden's repair goo, but they seems to have
replaced it with a silicon based adhesive now.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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Peter Wieck
2017-06-12 16:01:57 UTC
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I use a very soft hot-melt glue in a zig-zag pattern over the back of the tear where accessible. Just a tiny bead back and forth such as a spider does with its signal-strand on- its web. On the front, I use fine rayon cloth using either fabric cement or good old Contact Adhesive. The hot-melt glue stops the tear from propagating by adding strength beyond the immediate damage. Rayon, as a synthetic will not harden or rot.

Keep in mind that these are 30s/40s/50s single-speaker radios not known for being the highest fidelity devices available. So, the goal here is a permanent fix that also addresses long-term stability.

It is not a bad idea to coat the entire cone with a mix of rubber-cement and solvent (1:1) either as when these paper cones dry out, they can start to get very fragile. The mix helps bind the fibers and reduce brittleness.

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Peter Wieck
Melrose Park, PA
analogdial
2017-06-12 17:20:27 UTC
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Post by Peter Wieck
I use a very soft hot-melt glue in a zig-zag pattern over the back of the tear where accessible. Just a tiny bead back and forth such as a spider does with its signal-strand on- its web. On the front, I use fine rayon cloth using either fabric cement or good old Contact Adhesive. The hot-melt glue stops the tear from propagating by adding strength beyond the immediate damage. Rayon, as a synthetic will not harden or rot.
Keep in mind that these are 30s/40s/50s single-speaker radios not known for being the highest fidelity devices available. So, the goal here is a permanent fix that also addresses long-term stability.
It is not a bad idea to coat the entire cone with a mix of rubber-cement and solvent (1:1) either as when these paper cones dry out, they can start to get very fragile. The mix helps bind the fibers and reduce brittleness.
http://s.hswstatic.com/gif/spider-17.jpg
Peter Wieck
Melrose Park, PA
Rayon is treated cellouse. It's biodegradable, although I'm pretty sure
it will hold up better than the rest of the cone.
Sofa Slug
2017-06-13 01:04:17 UTC
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Post by o***@gmail.com
As providence would have it, I actually have an exact speaker in the boneyard, but it's got two tears in it but fortunately also has a very free moving VC. So the good news is that my efforts in recapping this worthless radio were not in vain.
Without starting a war here, I am interested in hearing some favorite fixes for stabilizing torn speaker cones, particularly any newer methods.
I've seen some references to GC Service Cement and I thought I possessed a bottle, but what I actually have is some GC General Purpose Plastic Cement which has a different part number and is now discontinued. It also claims to remain a bit flexible as the Service Cement does.
I painted some old pulpy paper with this cement straight out of the bottle, then painted another sample with a 50/50 dilution of this same cement and acetone (to allow better absorption into the paper) then the final sample using the same diluted sample with thin paper painted into the sample paper.
The two diluted samples definitely flowed completely into the paper where the straight sample didn't seem to flow through.
After an hour, all three paper samples are eminently flexible (including the one with the reinforcing paper added), but I'm concerned about the long term prospects of this particular cement to become brittle over time.
Any insight appreciated.
John
Wolcott, CT
If they aren't major, I've had good luck with coating both sides of the
tear with either rubber cement or black RTV. I haven't done a follow-up
check on really old rubber cement repairs, but the RTV repairs have been
very stable & have lasted for years (they also look better, if that's a
concern).
John Robertson
2017-06-13 04:51:56 UTC
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Post by Sofa Slug
Post by o***@gmail.com
As providence would have it, I actually have an exact speaker in the
boneyard, but it's got two tears in it but fortunately also has a very
free moving VC. So the good news is that my efforts in recapping this
worthless radio were not in vain.
Without starting a war here, I am interested in hearing some favorite
fixes for stabilizing torn speaker cones, particularly any newer methods.
I've seen some references to GC Service Cement and I thought I
possessed a bottle, but what I actually have is some GC General
Purpose Plastic Cement which has a different part number and is now
discontinued. It also claims to remain a bit flexible as the Service
Cement does.
I painted some old pulpy paper with this cement straight out of the
bottle, then painted another sample with a 50/50 dilution of this same
cement and acetone (to allow better absorption into the paper) then
the final sample using the same diluted sample with thin paper painted
into the sample paper.
The two diluted samples definitely flowed completely into the paper
where the straight sample didn't seem to flow through.
After an hour, all three paper samples are eminently flexible
(including the one with the reinforcing paper added), but I'm
concerned about the long term prospects of this particular cement to
become brittle over time.
Any insight appreciated.
John
Wolcott, CT
If they aren't major, I've had good luck with coating both sides of the
tear with either rubber cement or black RTV. I haven't done a follow-up
check on really old rubber cement repairs, but the RTV repairs have been
very stable & have lasted for years (they also look better, if that's a
concern).
I read of an old trick for re-centering voice coils years ago. As I
recall you determine which direction you need the to move slightly then
you apply a glue that shrinks when it dries in a narrow strip from near
the voice coil straight out. When the glue dries it tightens up the
paper cone on that side and pulls the voice coil with it. I last saw
that tip around 30 years ago and have no idea which book it is in, some
radio repair book obviously or a trade magazine from the 50s/60s...

I can't recall the glue though it may have been either model airplane
cement or wood glue (white glue).

You could always contact a speaker rebuild shop and ask them how they
tweak cones to center the VC.

Your mileage will vary!

John :-#)#

(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
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John-Del
2017-06-13 11:14:54 UTC
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Post by John Robertson
Post by Sofa Slug
Post by o***@gmail.com
As providence would have it, I actually have an exact speaker in the
boneyard, but it's got two tears in it but fortunately also has a very
free moving VC. So the good news is that my efforts in recapping this
worthless radio were not in vain.
Without starting a war here, I am interested in hearing some favorite
fixes for stabilizing torn speaker cones, particularly any newer methods.
I've seen some references to GC Service Cement and I thought I
possessed a bottle, but what I actually have is some GC General
Purpose Plastic Cement which has a different part number and is now
discontinued. It also claims to remain a bit flexible as the Service
Cement does.
I painted some old pulpy paper with this cement straight out of the
bottle, then painted another sample with a 50/50 dilution of this same
cement and acetone (to allow better absorption into the paper) then
the final sample using the same diluted sample with thin paper painted
into the sample paper.
The two diluted samples definitely flowed completely into the paper
where the straight sample didn't seem to flow through.
After an hour, all three paper samples are eminently flexible
(including the one with the reinforcing paper added), but I'm
concerned about the long term prospects of this particular cement to
become brittle over time.
Any insight appreciated.
John
Wolcott, CT
If they aren't major, I've had good luck with coating both sides of the
tear with either rubber cement or black RTV. I haven't done a follow-up
check on really old rubber cement repairs, but the RTV repairs have been
very stable & have lasted for years (they also look better, if that's a
concern).
I read of an old trick for re-centering voice coils years ago. As I
recall you determine which direction you need the to move slightly then
you apply a glue that shrinks when it dries in a narrow strip from near
the voice coil straight out. When the glue dries it tightens up the
paper cone on that side and pulls the voice coil with it. I last saw
that tip around 30 years ago and have no idea which book it is in, some
radio repair book obviously or a trade magazine from the 50s/60s...
I can't recall the glue though it may have been either model airplane
cement or wood glue (white glue).
I wonder if you're referring to animal hide glue. I know that when used in bonding wood, it shrinks as it dries pulling the parts tighter together (which makes it PERFECT for building musical instruments).

In my case though, it looks like the pole piece broke loose and slammed into the side trapping the VC.

If found a donor speaker but my next plan was to drill a hole down the center of the pole piece, insert a screw or rod and see if I couldn't shift the pole piece back. I may try it for S&Giggles anyway.

John
Peter Wieck
2017-06-13 12:39:21 UTC
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Try this:

Using an old-fashioned compass, cut out the center of the speaker cone with the VC, first cutting/desoldering the wires somewhere near the transformer, but with enough slack to re-connect. This will allow you to remove the entire VC. Then, you have the option of either working on the groove to restore clearances, or to actually rewind the VC altogether. I had to do this with a very vintage 1920s Zenith tallboy that had !Square! !Aluminum! VC wire which had been subject to sufficient current to fuse several windings. I rewound using square enameled copper wire of a slightly smaller cross-section (Jewelry Findings suppliers stock this stuff) that I annealed first then enameled myself. Worked fine (and still does 10 years later). I re-installed the piece by installing about a dozen tabs on the remaining cone, then resting (and gluing) the cut piece on them, then using the soft-formula hot-melt to complete and seal the joint. Anything becomes possible if the alternative is landfill.

Peter Wieck
Melrose Park, PA
John-Del
2017-06-13 19:16:04 UTC
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Post by o***@gmail.com
One of my customers (an older lady) was enamored by a very ordinary old Philco AM radio that was kicking around my shop. I thought she'd be thrilled to have this as a gift so over the next week in between jobs I slowly recapped it, put in a new AC cord, checked and replaced the couple of cranky loctals, cleaned, lubed, and reset a couple of shorting gang sections on the tuner. Sounds like crap; low power and distortion when the volume is advanced beyond one quarter.
Yep, frozen voice coil. I mean zero movement. I used some acetone to dissolve the adhesive holding the dust cap to remove it and it looks like the pole piece is slammed to one side pinning the VC to the frame.
This really stinks because the speaker frame assy also locates the dial assy in the radio. The good thing is that I didn't get to restoring the cabinet.
More evidence that no deed goes unpunished!
John
Wolcott, CT
Last question: this radio has a faux wood grain painted on it's plywood cabinet. It's a base coat of light brown and a thin top coat of dark brown paint. The dark brown coat on the topside has mostly blistered off (from the heat I presume) so I used a Scotchbrite pad and removed most of the flakes. The base coat is solid so I'd like to just give this a quick dark brown coat and simulate as much as possible the original type grain and come close to matching the remaining dark brown on the sides.

Is there a preferred dark brown paint to use as a top coat? Suggestions or links would be greatly appreciated.

John
Wolcott, CT
Peter Wieck
2017-06-13 19:24:16 UTC
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Post by John-Del
Last question: this radio has a faux wood grain painted on it's plywood cabinet. It's a base coat of light brown and a thin top coat of dark brown paint. The dark brown coat on the topside has mostly blistered off (from the heat I presume) so I used a Scotchbrite pad and removed most of the flakes. The base coat is solid so I'd like to just give this a quick dark brown coat and simulate as much as possible the original type grain and come close to matching the remaining dark brown on the sides.
Is there a preferred dark brown paint to use as a top coat? Suggestions or links would be greatly appreciated.
Krylon lacquer-based products tend to be the most compatible with OEM finishes. I would start there. I am not sure if they make a brown to your taste ( http://www.krylon.com/spray-paint-color-center/colors/brown-spray-paint/ ), but it is a good place to start.

Peter Wieck
Melrose Park, PA
John-Del
2017-06-13 19:53:08 UTC
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Post by Peter Wieck
Post by John-Del
Last question: this radio has a faux wood grain painted on it's plywood cabinet. It's a base coat of light brown and a thin top coat of dark brown paint. The dark brown coat on the topside has mostly blistered off (from the heat I presume) so I used a Scotchbrite pad and removed most of the flakes. The base coat is solid so I'd like to just give this a quick dark brown coat and simulate as much as possible the original type grain and come close to matching the remaining dark brown on the sides.
Is there a preferred dark brown paint to use as a top coat? Suggestions or links would be greatly appreciated.
Krylon lacquer-based products tend to be the most compatible with OEM finishes. I would start there. I am not sure if they make a brown to your taste ( http://www.krylon.com/spray-paint-color-center/colors/brown-spray-paint/ ), but it is a good place to start.
Peter Wieck
Melrose Park, PA
Thanks Peter, but since this is a "woodgrain" deal it must be brushed on - at least the second coat. I think spray bombs would dry too quickly to allow brushing out a convincing wood grain look.

Looking at it further, I might be better off sanding, sealing, and putting down a new light brown coat and follow it up with a brushed thin coat of dark brown.

I'll head over to Joanne's or Michaels with my wife (she lives there) and pick up a couple of cans of enamel.

John
Wolcott, CT
Peter Wieck
2017-06-13 20:10:51 UTC
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Hmmmm..... How about brushing it out with lacquer-thinner and seeing what you come up with? Perhaps add some dark brown lacquer at the same time? And when done, do the entirety with clear-gloss or clear semi-gloss? Nothing lost but a little bit of time.

Most of these vintage radios used lacquer as the OEM finish as the stuff dried lightening fast by the standards of other materials back-in-the-day, and time was money, even then.

Peter Wieck
Melrose Park, PA
John Robertson
2017-06-13 21:35:47 UTC
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Post by o***@gmail.com
One of my customers (an older lady) was enamored by a very ordinary old Philco AM radio that was kicking around my shop. I thought she'd be thrilled to have this as a gift so over the next week in between jobs I slowly recapped it, put in a new AC cord, checked and replaced the couple of cranky loctals, cleaned, lubed, and reset a couple of shorting gang sections on the tuner. Sounds like crap; low power and distortion when the volume is advanced beyond one quarter.
Yep, frozen voice coil. I mean zero movement. I used some acetone to dissolve the adhesive holding the dust cap to remove it and it looks like the pole piece is slammed to one side pinning the VC to the frame.
This really stinks because the speaker frame assy also locates the dial assy in the radio. The good thing is that I didn't get to restoring the cabinet.
More evidence that no deed goes unpunished!
John
Wolcott, CT
Last question: this radio has a faux wood grain painted on it's plywood cabinet. It's a base coat of light brown and a thin top coat of dark brown paint. The dark brown coat on the topside has mostly blistered off (from the heat I presume) so I used a Scotchbrite pad and removed most of the flakes.. The base coat is solid so I'd like to just give this a quick dark brown coat and simulate as much as possible the original type grain and come close to matching the remaining dark brown on the sides.
Is there a preferred dark brown paint to use as a top coat? Suggestions or links would be greatly appreciated.
John
Wolcott, CT
It is not too difficult to create a faux wood finish. There are a number
of tutorials on youtube from the car folks (woodies).

John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
John-Del
2017-06-18 13:07:04 UTC
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Post by o***@gmail.com
One of my customers (an older lady) was enamored by a very ordinary old Philco AM radio that was kicking around my shop. I thought she'd be thrilled to have this as a gift so over the next week in between jobs I slowly recapped it, put in a new AC cord, checked and replaced the couple of cranky loctals, cleaned, lubed, and reset a couple of shorting gang sections on the tuner. Sounds like crap; low power and distortion when the volume is advanced beyond one quarter.
Yep, frozen voice coil. I mean zero movement. I used some acetone to dissolve the adhesive holding the dust cap to remove it and it looks like the pole piece is slammed to one side pinning the VC to the frame.
Update:

I finished repairing the torn cone in the replacement speaker, and before I pitched the jammed speaker out, I experimented with it. Under an eyeloop,I could see where the magnet had shifted by seeing a crack in the silver paint on one side. I put the speaker in a vice, and hit it with a drift to shift the pole piece, and the VC released. Works nice and smooth without a hint of rub. I'm going to keep it around to see if it drifts back to it's starting position.

While letting it run, it stopped working after about 20 hours, and I found the 14AF7 converter tube dead, or at least intermittent. I put in a used one that came from the other radio that donated the speaker and it's back in business.

I picked up a "sample" size container of paint from Home Depot ($3 and change) and selected the darkest brown I could find. It's a bit lighter in tone than the original paint but I brushed it on thinly and it blended in pretty well with an almost convincing "grain". Just a satin clear top coat to finish it which should also darken it a touch.

Before I pitched the old paper capacitors, I always check them for the heck of it and found that every one of the original Philco labelled paper caps were *perfect*, something I did not expect to find. All paper caps measured high in value (typical for these old paper caps) but showed zero leakage at 100 volts.

Does anyone know if Philco actually had their own capacitor production or were they simply house labelled for them?

This radio has a loop antenna built into the cabinet, not the rear cover (which is AWOL anyway). It's about 20 turns of thin enameled wire that runs around the perimeter of the rear opening. I epoxied a terminal to the inside of the cabinet and soldered the thin antenna wires to it, then added a plug with an 8" pigtail to the radio in order provide both a quick disconnect for the antenna and avoid having to deal with the fine antenna wires being soldered directly to the radio chassis.

John
Wolcott, CT
Foxs Mercantile
2017-06-18 13:17:46 UTC
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Post by John-Del
Before I pitched the old paper capacitors, I always check
them for the heck of it and found that every one of the
original Philco labelled paper caps were*perfect*
My experience is different.
I've also had some Philco caps across line voltage fail in
a spectacular fashion.

But, great job on the old radio sir.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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John-Del
2017-06-18 19:52:43 UTC
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Post by Foxs Mercantile
Post by John-Del
Before I pitched the old paper capacitors, I always check
them for the heck of it and found that every one of the
original Philco labelled paper caps were*perfect*
My experience is different.
I've also had some Philco caps across line voltage fail in
a spectacular fashion.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
Could have been a magical batch I suppose!

Just strange to see no leakage whatsoever on 70 year old caps. I've seen a few here and there out of a batch replaced from the same radio that were good, but never saw every single one perfect leakage-wise.

Almost as strange was the multi section electrolytic which was replaced at some point before I acquired the radio (and I don't remember that either). This read perfect in value but *very* leaky at the voltages the radio uses, and it wouldn't reform (not that I would leave it in if it did, but just for morbid curiosity).

One more week of running and off it goes to the nice old lady. I'm sure the look on her face when I give her the old Philco will make this all worth it.

John
Wolcott, CT
Foxs Mercantile
2017-06-18 20:47:07 UTC
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it wouldn't reform (not that I would leave it in if it did.
Good, another one with enough sense not to waste anybody's
time reforming old electrolytics.
One more week of running and off it goes to the nice old lady.
I'm sure the look on her face when I give her the old Philco
will make this all worth it.
Been there, done that, and yes it is.

Back in Los Angeles, I restored a early '30s Philco and delivered
it to the customer's house. The First station I tuned in was the
local Tex Mex station. "See it works, and we even taught it to
speak Spanish."

That got a few laughs. Then the wife says, "This was my grand-
fathers radio. I remember as a little girl sitting with him and
listening to opera on it."
I twiddled the dial down and coincidentally landed on a opera
station.

She immediately started crying. I turned to the husband, "Are
those 'happy' tears or 'start running' tears?"
His reply was "I never could tell the difference." I said,
"Neither could I, but she doesn't seem to be reaching for any
thing sharp."

She turned around, gave me a hug and dribbled tears all over
my shoulder. "Thank you so very much."

I guess that answered that question.

She made up for all the asshole customers I had had previously.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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