1960s-1970s Telephone Repair

[J. B. Wood]

Hello, all, especially those with familiarity with subject. I've got a
decades-old Stromberg-Carlson SC-2554 wall mount phone. It's still in
great shape except recently a small white piece of plastic on the
make/break hook switch broke rendering the rest of the cradle mechanism
inoperative. The plastic piece finally broke from the tension from the
return spring. It's a clean break but I'm afraid that even if I can
glue the pieces back together it will most likely fail again in short
order. Thanks for your time and your comment is most appreciated.
Sincerely,
--
J. B. Wood e-mail: arl_1...@hotmail.com

[Baron]

J. B. Wood prodded the keyboard with:

You could always try a steel pin heated hot enough to sink into the
plastic, a bit like a staple, or cross drill it and press a staple in
the holes.

--
Best Regards:
Baron.

[Jeff Liebermann]

Glue the broken parts back together but do NOT reinstall them in the
phone. Instead, find someone with a 3D digitizer and 3D printer who
can make a reproduction of the original. I'm not familiar with SC
phones, but the equivalent part in a Western Electric wall phone is a
flat plate with two rectangular holes. That can probably be machined
out of plastic. I couldn't find a photo with Google Images.

Are you sure about the model number? The SC number was SC-554 while
the WE number was 2554.

SC-554:
<https://www.youtube.com/watch?v=cDP6I8bEP8o>

WE 2554:
<https://www.youtube.com/watch?v=VedsBJfsLlo>


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[dansabr...@yahoo.com]

There is a line of products of which Plastic-Weld is one that I have used with much success over the years for similar types of problems. This is a solvent based "glue" that actually dissolves the plastic a bit and reforms it. The joint essentially disappears. Caution though, don't press together too much or you will deform the plastic. Only apply enough pressure to be sure that the two parts meet firmly.

Dan

[Don Y]

Your description is vague.

Is the plastic piece part of the housing? Or, a mechanical actuator that
conveys the hookswitch's state to the actual switch?

Said another way, does the phone *appear* (visually) to be intact -- but,
some INTERNAL mechanism is broken that allows it to FUNCTION as it should?

(Could you, perhaps, post a picture on a hosting site with a link, here?)

[J. B. Wood]

On 04/10/2016 04:42 PM, Jeff Liebermann wrote:

> Are you sure about the model number? The SC number was SC-554 while
> the WE number was 2554.
>
> SC-554:
> <https://www.youtube.com/watch?v=cDP6I8bEP8o>
>
> WE 2554:
> <https://www.youtube.com/watch?v=VedsBJfsLlo>
>
>

Thanks for the response, Jeff. The number stamped on the back of the
instrument is S-C 2554BPM. Perhaps the "2" designated a DTMF type dial?

[J. B. Wood]

Thanks for the follow-up, Dan. Are you referring to one of the products
from http://www.jbweld.com/collections/plastic-composite-pvc?

If so, is there a specific one from this company that you can recommend?
Thanks. Sincerely,

[J. B. Wood]

On 04/11/2016 07:13 AM, Don Y wrote:

> Your description is vague.
>
> Is the plastic piece part of the housing? Or, a mechanical actuator that
> conveys the hookswitch's state to the actual switch?
>
> Said another way, does the phone *appear* (visually) to be intact -- but,
> some INTERNAL mechanism is broken that allows it to FUNCTION as it should?
>
> (Could you, perhaps, post a picture on a hosting site with a link, here?)

Hello, and yeah, I kind of figured that might be a problem. It's just a
small piece of plastic that separates the electrical contacts on the
hook switch. A small shaft which passes through the plastic piece upon
which a spring-loaded bracket pivots. This bracket makes contact with
the arm that determines whether the handset is on or off the cradle.
The plastic split right where that small shaft passes. Sincerely,

[pf...@aol.com]

Mpfffff... take out the part. Put it back together with JB Weld - available everywhere. Be sloppy with the material, but make sure that you do not glue the part to anything else. I will on occasion tie such a part together with fine thread (if there are holes through it, even better) and suspend it during the curing process. Then with files, X-Acto and sandpaper, reshape the part to its correct size, removing flash and sprue, so to write. Re-drill any filled holes and you are done. JB Weld will be harder and stronger than the OEM plastic by a considerable margin.

Peter Wieck
Melrose Park, PA

[Chuck]

On Sun, 10 Apr 2016 16:12:40 -0400, "J. B. Wood"
<john...@nrl.navy.mil> wrote:

I have had good luck with some plastic parts using Gorilla super glue.

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[pf...@aol.com]

On Monday, April 11, 2016 at 9:22:11 AM UTC-4, Chuck wrote:
> On Sun, 10 Apr 2016 16:12:40 -0400, "J. B. Wood"

>

> I have had good luck with some plastic parts using Gorilla super glue.
>

In most cases, I would suggest super glue - Gorilla or otherwise. But many phone parts are made from Delrin® (Polyoxymethylene), which also happens to be one of the materials used to deliver super-glue as it does not stick to Delrin. I am not stating that this particular part is Delrin - but a great many friction and contactor parts are made from that material because of its self-lubricating and excellent insulating properties. Further to this, it naturally repels metallic dust and powder, such as could build up and arc.

JB Weld *does* stick to Delrin reasonably well, and has enough self-integrity to bridge and fill.

[dansabr...@yahoo.com]

The product I am referencing is NOT JB-Weld. The product is made by Plastruct and is called Plastic Weld. It is a clear liquid not an epoxy that actually dissolves the plastic and allows for reformation. It is considered a plastic solvent and cement.

Dan

[pf...@aol.com]

On Monday, April 11, 2016 at 10:30:40 AM UTC-4, dansabr...@yahoo.com wrote:
> The product I am referencing is NOT JB-Weld. The product is made by Plastruct and is called Plastic Weld. It is a clear liquid not an epoxy that actually dissolves the plastic and allows for reformation. It is considered a plastic solvent and cement.
>
> Dan

Dan:

If that part *is* Delrin, it will be entirely impervious to Plastic Weld. As will be many high density, self-lubricating plastics.

The material you suggest is useful on the polystyrene/acrylic based materials, not so much on others.

[Jeff Liebermann]

Ah, that's a better number. There's one for sale on eBay if you need
parts:
<www.ebay.com/itm/STROMBERG-CARLSON-2554-BPM-Wall-Mounted-Single-Line-Corded-Phone-/281979044418>

It's impossible to get into a discussion on adhesives without everyone
recommending their favorite potions, concoctions, and methods. I'll
just make things worse.

My guess(tm) is that the plastic in the phone is probably ABS (acrylic
butyl styrene) which will weld nicely with acetone solvent. There are
overpriced potions available that are mostly acetone, but might
include other solvents (MEK, toluene, etc).
<http://nerfhaven.com/forums/topic/18527-intro-to-solvent-welding-plastic/>

Superglue (cyanoacrylate) is too brittle and mutilates acrylics.
<http://info.craftechind.com/blog/bid/323475/Stick-to-it-A-Guide-to-the-Best-Glue-for-Plastic>

Urethane adhesives, such as Gorilla Glue, don't do well with many
plastics because they do NOT contain any solvents. Fortunately, the
phone switch insulator (or whatever it's called) sees force in only
one direction, so marginal adhesives will probably work, for a while.

Just to muddy the waters, I've been learning plastic welding using
some home made brass nozzles attached to my SMT desoldering station
hot air gun. When it works, it works great. When I do something
wrong, it destroys the part. Plastic welding works best for me on
large plastic parts, and not so good on small plastic parts.

I'm also a fan of hot melt glue, but that's not appropriate for this
job. However, if you do decide to try hot melt glue, be sure to get
the correct type of adhesive stick:
<https://en.wikipedia.org/wiki/Hot-melt_adhesive>

Good luck.

[Jeff Liebermann]

On Mon, 11 Apr 2016 07:30:34 -0700 (PDT), dansabr...@yahoo.com
wrote:

A URL is amazingly helpful:
<http://www.amazon.com/Plastruct-Plastic-Weld-applicator-2oz/dp/B00FDFWJD8>
The MSDS at:
<http://plastruct.com/wp-content/uploads/2015/06/MSDS_PPC_2.pdf>
says that it's:
Methylene Chloride (Dichloromethane) 80-90%
Methyl Ethyl Ketone (MEK) 5-15%
Yep, that will certainly work for ABS, PVC, and various styrene
plastics.

However, methyl chloride is rather dangerous. The EU banned the stuff
in 2011. It was commonly used for furniture stripper before it was
recognized as hazardous:
<https://www.cdph.ca.gov/programs/hesis/Documents/MethyleneChlorideAlert.pdf>
Suggestion: Use the stuff outdoors and wear the usual protection
(breather, glasses, gloves, etc).

Plastruct video:
<https://www.youtube.com/watch?v=979eXts6DwM> (1:23)

[et...@whidbey.com]

I don't know what kind of plastic your part is but there is a two part
plastic cement that bonds well to many of the plastics that are hard
to glue. I don't remember the name but I think it is made by Loctite
which has lots of epoxies and the like at hardware stores. Anyway, the
stuff is made specifically for plastic repair, not general repair jobs
like JB Weld (which is pretty good stuff) and 5 minute epoxy and the
like. I have used the stuff and it worked very well. Smelled bad when
curing but no smell once cured. I even used it in a test repair. The
radiator in our Toyota Camry developed a crack in the upper plastic
part of the radiator. I ordered a new radiator and while waiting for
it tried this plastic repair stuff. I cleaned and roughed up the
plastic, slathered on the glue, then I laid a piece of cloth which was
saturated with the glue on top. After it set the car was driven for a
couple weeks before I replaced the radiator. The patch never gave up
and the radiator got hotter than the recommended highest temperature
for the glue. I don't know how long the patch would have lasted but
since it was on the car I installed the new radiator.
Eric

[Phil Hobbs]

Methyl chloride (CH3Cl) != methylene chloride (CH3Cl2). The stuff with
the shorter name is pretty evil, but the longer stuff you can
practically drink. (Just joking, kids. Don't drink paint remover.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[Phil Hobbs]

CH2Cl2.

[Jeff Liebermann]

On Mon, 11 Apr 2016 09:51:46 -0700, et...@whidbey.com wrote:

>I don't know what kind of plastic your part is but there is a two part
>plastic cement that bonds well to many of the plastics that are hard
>to glue. I don't remember the name but I think it is made by Loctite

<http://www.loctiteproducts.com/p/sg_plstc/overview/Loctite-Plastics-Bonding-System.htm>

Cyanoacrylate resin and MEK as "activator". Works quickly and great
for most plastics. However, the MEK tends to dry out prematurely in
the bottle. Have some extra MEK handy if you're going to use it.
Also, make sure everything is free of grease or it won't stick.

[Jeff Liebermann]

On Mon, 11 Apr 2016 14:03:54 -0400, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>Methyl chloride (CH3Cl) != methylene chloride (CH3Cl2). The stuff with
>the shorter name is pretty evil, but the longer stuff you can
>practically drink. (Just joking, kids. Don't drink paint remover.)

Oops. Thanks for the correction. I thought they were the same stuff.

>Cheers

Grumble...
Jeff L.

>Phil Hobbs

[et...@whidbey.com]

On Mon, 11 Apr 2016 11:48:37 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>On Mon, 11 Apr 2016 09:51:46 -0700, et...@whidbey.com wrote:
>
>>I don't know what kind of plastic your part is but there is a two part
>>plastic cement that bonds well to many of the plastics that are hard
>>to glue. I don't remember the name but I think it is made by Loctite
>
><http://www.loctiteproducts.com/p/sg_plstc/overview/Loctite-Plastics-Bonding-System.htm>
>
>Cyanoacrylate resin and MEK as "activator". Works quickly and great
>for most plastics. However, the MEK tends to dry out prematurely in
>the bottle. Have some extra MEK handy if you're going to use it.
>Also, make sure everything is free of grease or it won't stick.

Greetings Jeff,
The stuff I'm talking about is not a cyanoacrylate resin and activator
system. It is two parts that must be mixed and then applied. This is
the stuff. I think. See the link:
http://www.homedepot.com/p/Loctite-0-85-fl-oz-Plastic-Epoxy-1360788/100371824

Eric

[et...@whidbey.com]

On Mon, 11 Apr 2016 09:06:48 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

ABS=Acrylonitrile butadiene styrene.

[Jeff Liebermann]

On Mon, 11 Apr 2016 12:09:30 -0700, et...@whidbey.com wrote:

>On Mon, 11 Apr 2016 09:06:48 -0700, Jeff Liebermann <je...@cruzio.com>
>wrote:

>>My guess(tm) is that the plastic in the phone is probably ABS (acrylic
>>butyl styrene) which will weld nicely with acetone solvent.

>ABS=Acrylonitrile butadiene styrene.

Sigh. I stand corrected (again). Thanks.

[Jeff Liebermann]

Do you recall if the goo you used took 5 min or 20 min to set?

The Home Despot ad above shows "Epoxy Plastic" with a 5 minute time to
set. However, I couldn't find that on the Loctite web pile, but found
this instead:
<http://www.loctiteproducts.com/p/epxy_plstc_s/overview/Loctite-Epoxy-Plastic-Bonder.htm>
which is a "Plastic Epoxy Bonder" with a 20 minute time to set. I
prefer the longer setting times and overnight hardening, so I'll start
with the 20 min flavor.

The Plastic Epoxy Bonder stuff is NOT an epoxy. Epoxy is a
thermosetting plastic. The Plastic Epoxy Bonder is an acrylic, which
is thermoplastic. See first question at:
<http://juxtamorph.com/difference-between-polyester-acrylic-and-epoxy-resins/>
That's fine because an acrylic based glue is what you want for ABS
anyway.

I suspect it also has some sort of solvent to soften the base plastic.
Looks like the formulation has changed slightly:
<http://henkelconsumerinfo.com/products/henkel.datasheets.DownPdf.pdf?BUSAREA=0006&VKORG=3450&MATNR=1442491&RECNDH=20257403&ACTNDH=0&LANG=EN&COUNTRY=US>
<http://www.menards.com/msds/107040_001.pdf> (older)
Yep, 1% carbon tetrachloride solvent, which should do nicely for
softening plastics. Three different forms of methyl methacrylate
(MMA). Incidentally, MMA was once used for fake finger nails, but was
banned for some reason:
<http://www.hooked-on-nails.com/mmaandyou.html>
I'm not sure what the other stuff does and am too lazy to dig it out.

So, what you have here is an acrylic plastic glue, with some rubber
compound added to make it a little flexible, no epoxy resin anywhere
in sight, and a bit of solvent to soften the base plastic.
Also see the data sheet at:
<http://www.loctiteproducts.com/tds/EPXY_PLSTC_S_tds.pdf>

The 5 min "Epoxy Plastic" MSDS is rather cryptic:
<http://henkelconsumerinfo.com/products/henkel.datasheets.DownPdf.pdf?BUSAREA=0006&VKORG=3450&MATNR=1071291&RECNDH=20924077&ACTNDH=0&LANG=EN&COUNTRY=US>
<http://henkelconsumerinfo.com/products/henkel.datasheets.DownPdf.pdf?BUSAREA=0006&VKORG=3450&MATNR=1071250&RECNDH=21213716&ACTNDH=0&LANG=EN&COUNTRY=US>
and only shows "epoxy resin, proprietary". The hardener is listed as
"tertiary amine" which is an epoxy resin curing agent.

I would go for the 20 minute flavor.

[et...@whidbey.com]

On Mon, 11 Apr 2016 15:28:32 -0700, Jeff Liebermann <je...@cruzio.com>

I don't remember if the stuff was 5 or 20 minutes but I suspect it was
the 5 minute variety. I wondered about that epoxy name. Looking at the
ingredients made me think it wasn't an epoxy but I don't know enough
about epoxies to tell. I do know that there are some pretty damn good
acrylic based adhesives though. I suspect that the adhesive backed
aluminum tape made for ductwork (not duct tape!) uses an acrylic based
adhesive. That stuff sticks remarkably well and does so for years.
Eric

[Bennett]

While it admits to not addressing the fine points of gluing all the
different sorts of plastics, this web site is often really handy:
www.thistothat.com

On 4/10/2016 1:12 PM, J. B. Wood wrote:

[DaveC]

> I don't know what kind of plastic your part is but there is a two part
> plastic cement that bonds well to many of the plastics that are hard
> to glue. I don't remember the name

I’ve had great success mending most plastics of all kinds (varying degrees
with poly-types) using Devcon Plastic Welder:

http://www.amazon.com/Devcon-22045-Plastic-Welder-Dev-Tube/dp/B003NUGL9S

It’s my go-to solution when fixing anything plastic.

Cool phone. Brings back memories. Ours was (at different times, replacements
installed after family of 6 abused it) red, yellow, black, white. With
extra-long handset cord, of course.

Good luck.

[DaveC]

History of the development of the Model 500 phone:

https://en.wikipedia.org/wiki/Model_500_telephone

Fascinating...

[Jeff Liebermann]

On Mon, 11 Apr 2016 23:05:33 -0700, DaveC <n...@home.cow> wrote:

>> I don't know what kind of plastic your part is but there is a two part
>> plastic cement that bonds well to many of the plastics that are hard
>> to glue. I don't remember the name
>
>I’ve had great success mending most plastics of all kinds (varying degrees
>with poly-types) using Devcon Plastic Welder:
>
>http://www.amazon.com/Devcon-22045-Plastic-Welder-Dev-Tube/dp/B003NUGL9S
>
>It’s my go-to solution when fixing anything plastic.

Well, at least Devcon doesn't claim that it's an epoxy. From the MSDS
sheet at:
<http://www.itwconsumer.com/userfiles/files/msds/DV-MSDS/22045.pdf>
it appears to be similar to the MMA based Loctite Plastic Epoxy Bonder
but without the carbon tetrachloride solvent to soften the base
plastic.

Data sheet:
<http://www.itwconsumer.com/userfiles/files/techdata-sheet/DV%20Tech%20Data/22045%20TDS.pdf>
"Not recommended for use on copper or brass"

>Cool phone. Brings back memories. Ours was (at different times, replacements
>installed after family of 6 abused it) red, yellow, black, white. With
>extra-long handset cord, of course.

Same here, but with fewer phones and colors. In college, I helped
build a private exchange, complete with direct dialing and rotary
steppers, in the dorms. Everything was "donated", which translated
from student slang meant stolen. This was approximately when we first
walked on the moon, so the administration was tolerant of anything
that might be considered science and resisted the temptation to throw
all us phone phreaks out of skool. Yep, fond memories.

[J.B. Wood]

On 04/10/2016 04:12 PM, J. B. Wood wrote:
> Hello, all, especially those with familiarity with subject. I've got a
> decades-old Stromberg-Carlson SC-2554 wall mount phone. It's still in
> great shape except recently a small white piece of plastic on the
> make/break hook switch broke rendering the rest of the cradle mechanism
> inoperative. The plastic piece finally broke from the tension from the
> return spring. It's a clean break but I'm afraid that even if I can
> glue the pieces back together it will most likely fail again in short
> order. Thanks for your time and your comment is most appreciated.
> Sincerely,

Hello again, everyone and many thanks to all the timely responses from
Jeff L. and others. Just one additional comment: When that plastic hook
switch part breaks the phone will be permanently off-hook even with the
handset parked in the cradle. Also, while many usenet groups have
become silent, s.e.r is most certainly a notable exception! VTY,

[Michael A. Terrell]

Here is a brand new phone in that style for $33

http://www.ebay.com/itm/Scitec-Single-Line-Corded-Wall-Mount-Phone-Ash-2554W/301751024095

I had some of those, but no one wanted them. They ended up being
scrapped. I have a pile of WE & SC Touchtone keypads from several
hundred old 1A2 business phones that I scrapped, as well. I have a large
box of 400 series KTU cards, as well.

[J.B. Wood]

On 04/18/2016 02:03 PM, Michael A. Terrell wrote:
>
> Here is a brand new phone in that style for $33
>
> http://www.ebay.com/itm/Scitec-Single-Line-Corded-Wall-Mount-Phone-Ash-2554W/301751024095
>
> I had some of those, but no one wanted them. They ended up being
> scrapped. I have a pile of WE & SC Touchtone keypads from several
> hundred old 1A2 business phones that I scrapped, as well. I have a large
> box of 400 series KTU cards, as well.

Hello, and while I'm certainly grateful for all the responses to my OP
I'm sort of thinking that whatever adhesive I might use to glue that
plastic (nylon?) piece back together is at best short term. Trying to
staple the pieces together might work if the staples don't get in the
way of the contacts. Still kind of kludgy, though. And then there's
the prospect of reassembling all those hook switch contacts properly and
with the insulating spacers where they need to be. Once that cradle
return spring is put back into position it will most likely cause a
stress break in the same area again. The proper repair solution would
be to replace the entire switch hook assembly but that would entail
drilling out the rivets that mount it to the phone base plate and
attaching an identical (NOS ideally) replacement if I could obtain one.

[whit3rd]

On Monday, April 18, 2016 at 12:12:00 PM UTC-7, J.B. Wood wrote:

> Hello, and while I'm certainly grateful for all the responses to my OP
> I'm sort of thinking that whatever adhesive I might use to glue that
> plastic (nylon?) piece back together is at best short term.

Whatever made it come apart the first time, could just happen again.
Nylon doesn't glue well.
Maybe you could paint over the glued part with latex (available at
plastics suppliers as mold-making material), and use the mold
to make an epoxy duplicate?

[Heisenberg]

On Mon, 18 Apr 2016 21:11:05 -0700 (PDT), whit3rd <whi...@gmail.com>
wrote:

I worked for Telecom Australia in the 1970s.

=-=-
"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville
(*Diagnostic and Statistical Manual of Mental Disorders)