Author Topic: Brazilian Ericsson switchboard  (Read 2194 times)

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #15 on: July 28, 2017, 04:00:27 PM »
I believe this board should actually be wall-mounted, correct?
How else would the cords be able to retract properly ?
There were special tables for small swbds with a hole in the top for cords to hang through.

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #16 on: July 28, 2017, 04:07:48 PM »
From the small Kellogg cordless boards I know that they equipped only the 20-station boards with line relays, not the smaller ones.
Another possible reason for using line relays in the Kellogg board might have been that it was competing with WE 506-type cordless PBXs which used magnetic signals and as a matter of "specsmanship" (being able to state that it has the same operating range as the 506) relays were required to match the loop range of the 506.

It's also possible that at that time only carbon filament lamps were being made, which are less efficient than tungsten lamps used as line lamps in all cord swbds I know of which do not have line relays.  Carbon filament lamps probably have an even lower loop resistance range.

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #17 on: July 28, 2017, 04:11:05 PM »
I think the design with rounded corners may have been a post-WWII design in Sweden.
The white nylon relay coil front spool header and molded phenolic terminal blocks also suggest pretty late mfr, quite possibly 1950s or 60s.

Offline escuta

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Re: Brazilian Ericsson switchboard
« Reply #18 on: July 28, 2017, 04:16:55 PM »
Here a photo of a nicer looking freestanding version that was on sale here some time ago (more expensive than I could afford) and a second unit from Mexico. Yes, mine has a bracket at the back for wall-mounting

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #19 on: July 28, 2017, 04:22:21 PM »
Here a photo of a nicer looking freestanding version that was on sale here some time ago (more expensive than I could afford) and a second unit from Mexico. Yes, mine has a bracket at the back for wall-mounting
Funny how the dial seems to be cobbled onto both of them, as though not provided for in the original design. 

The second one is also equipped with a US payphone handset with metal armored cord.  The blue grommet on the bottom identifies it as being "hearing aid compatible", for compliance with the US ADA.  Hearing aid compatibility requires the receiver unit to emit a magnetic field for pickup by the hearing aid for clearer coupling of the received speech than would be possible acoustically.

unbeldi

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Re: Brazilian Ericsson switchboard
« Reply #20 on: July 28, 2017, 05:18:07 PM »
I found your switchboard, I believe.

In 1946 and 1950, Erik Iengqvist published two articles in Ericsson Review introducing a new series of manual switchboards.
The 1946 paper deals with local battery systems, while the 1950 paper extends the design to common battery operation.

ER 1946 v23(3) p250, New Series of Manual LB Switchboards with Cords
ER 1950 v27(2) p36, Manual Private Branch Switchboards with Cords

I have attached both articles.  Your board is of course in the second article, since it is a common battery switchboard.  The article also shows the dial attached in the same location.  One difference I see, is that your board does not appear to have the hand generator, but perhaps I only missed it.
« Last Edit: July 28, 2017, 05:36:41 PM by unbeldi »

Offline escuta

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Re: Brazilian Ericsson switchboard
« Reply #21 on: July 28, 2017, 05:38:15 PM »
That's amazing unbeldi, thank you very much! I'll have a good read through these tomorrow. Mine does have a hand generator positioned on the right hand side. The dial however, doesn't seem to be what looks like a Bakelite dial in the original though. I'll be back with more questions, no doubt. I really appreciate your help!

unbeldi

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Re: Brazilian Ericsson switchboard
« Reply #22 on: July 28, 2017, 05:44:54 PM »
That's amazing unbeldi, thank you very much! I'll have a good read through these tomorrow. Mine does have a hand generator positioned on the right hand side. The dial however, doesn't seem to be what looks like a Bakelite dial in the original though. I'll be back with more questions, no doubt. I really appreciate your help!

Ah, in your new pictures I do spot the generator now, in a view of the inside.   It is a characteristic Ericsson design and uses Alnico magnets, that Ericsson first introduced in the late 1930s.  Somewhere I have that article too, I researched Ericsson hand generators before.

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #23 on: July 28, 2017, 05:47:15 PM »
I found your switchboard, I believe.

ER 1946 v23(3) p250, New Series of Manual LB Switchboards with Cords
ER 1950 v27(2) p36, Manual Private Branch Switchboards with Cords

I have attached both articles. 
Did you find an entry point to the LME E-R archive with an index or find them somewhere else?

unbeldi

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Re: Brazilian Ericsson switchboard
« Reply #24 on: July 28, 2017, 05:59:49 PM »
Did you find an entry point to the LME E-R archive with an index or find them somewhere else?
I have an archive of most of ER 19242000 on my local disk for which I created a full-text search index.

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #25 on: July 28, 2017, 06:20:53 PM »
I have an archive of most of ER 19242000 on my local disk for which I created a full-text search index.
Ah!

Offline escuta

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Re: Brazilian Ericsson switchboard
« Reply #26 on: July 29, 2017, 09:46:14 AM »
Located the Ericsson Review page on the Ericsson website. It's here:

https://www.ericsson.com/en/about-us/history/sources/lme-review

And found a closer match for my board, the ADE 1210 from 1953 which is identical, however mine has a jack socket between the "S" (splitting key) button and the "~" (pole changer key) on the vertical panel. Not sure what this would be for.

Have attached a jpeg and 2 pages from ther 1953 PDF.

Cheers

unbeldi

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Re: Brazilian Ericsson switchboard
« Reply #27 on: July 29, 2017, 10:17:05 AM »
Located the Ericsson Review page on the Ericsson website. It's here:

https://www.ericsson.com/en/about-us/history/sources/lme-review

And found a closer match for my board, the ADE 1210 from 1953 which is identical, however mine has a jack socket between the "S" (splitting key) button and the "~" (pole changer key) on the vertical panel. Not sure what this would be for.

Have attached a jpeg and 2 pages from ther 1953 PDF.

Cheers

I don't see why you think it is a closer match.  That board is from the same model line and only the article is from 1953, not necessarily the board.  The article is an overview article of Ericsson's line of intercommunication systems.
The model line contained many versions with varying capacity and special features. The 1210 has 10 cord circuits, while yours has only eight cord circuits, the same as in the original paper of 1950, showing the 1205.

For reference:
ER 1953 v30(1) p13, O. Siewert, Modern Telephone Systems for Internal Communications
« Last Edit: July 29, 2017, 10:21:26 AM by unbeldi »

Offline escuta

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Re: Brazilian Ericsson switchboard
« Reply #28 on: July 29, 2017, 10:24:13 AM »
Mine has 10 slots for cord circuits, it's just that only 8 have been installed. Also the hook for the receiver is identical on the 1210 as is the location of the socket for the receiver cord. Yes, you're correct it may not be from 1953 but to me the 1210 looks the most similar.

Alex G. Bell

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Re: Brazilian Ericsson switchboard
« Reply #29 on: July 29, 2017, 03:51:37 PM »
Mine has 10 slots for cord circuits, it's just that only 8 have been installed. Also the hook for the receiver is identical on the 1210 as is the location of the socket for the receiver cord. Yes, you're correct it may not be from 1953 but to me the 1210 looks the most similar.

Is the ID plate shown in #7 the same one which appears at the upper right in #11 or are there two, one internal and one external?

In #15 (bottom view of key shelf) is there really space for two more cord assemblies between the furthest right and left cord units and the outer wall of the frame, which appears to be molded from black plastic?  It's hard to tell due to the perspective resulting from the camera being so close to the subject.  The fact that there are two blank plates on the top of the keyshelf does not necessarily mean 2 more cord circuit assemblies could be added.  Each cord circuit requires at least one relay, inductors or transformers ("repeat coils") mounted on the framework.  There may not be sufficient space for the parts required to support the cord & key assembly even if there is sufficient space for the keys and cords themselves.

A puzzling statement in the E-R article: "The telephone instruments ... are either normal C.B. instruments or, if the lines are short, instruments of the domestic type".  I suppose by "domestic type" they really mean internal type, i.e. series talking circuit type.  This seems to probably be a mis-translation from the Swedish.

It's too bad the quality of the PDF is so poor.  The text contains obvious JPG compression artifacts, appearing as speckles surrounding the text, from using too high a compression level.  I may have an original of this issue of the publication and may be able to scan it in the future, but not in the near future.
« Last Edit: July 29, 2017, 03:56:08 PM by Alex G. Bell »