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Old 19th May 2020, 3:32 pm   #1
Nickthedentist
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Default Converting a 1950s Ericsson phone for "normal" working

Hello everyone,

I recently got hold of a ~1950 Ericsson N1071A16 wall phone, which is also marked as type H1385, a New Zealand post office designation.

The numbers on the dial are backwards compared with what we're used to, but otherwise it's very similar to the UK variants, which have an almost standard 300-series chassis albeit modified to work in a wall-mounted case, see here: https://www.britishtelephones.com/ericsson/n1071.htm

The dial was a mess (seized clutch and broken return spring) but I've restored everything now and would like to use it at home.

However, there's a catch... this seems to be an instrument re-designed for the NZ telephone system. It has an extra changeover contact on the gravity switch and a separate earth connection. There's also an odd, asymmetrical leaf spring on the bell motor.

I've attached a photo of the paster in mine. You can see it's very similar indeed to the standard GPO 332: https://www.britishtelephones.com/gp...t322paster.jpg

So, to the big question... What do I need to do? Certainly, linking T2-T3 would be a start, connecting the line to the points marked A and B.

Two-wire working would be fine. And obviously, I realise that I'd need to do a bit of mental conversion when dialling!

Thanks, experts,

Nick.

EDIT: Mods, please delete the "party line" bit from the title
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Old 19th May 2020, 4:38 pm   #2
Dave Moll
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Quote:
Originally Posted by Nickthedentist View Post
Two-wire working would be fine. And obviously, I realise that I'd need to do a bit of mental conversion when dialling!

Thanks, experts,

Nick.
If you wanted to go for three-wire working, would removing the link between 10 and 11 then connecting the "ringing" wire to 11 achieve this?

To save the mental gymnastics, could you swap the dial, or at least the number ring, for a UK one?

And no, I don't claim to be an expert!
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Old 19th May 2020, 8:56 pm   #3
Pellseinydd
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Quote:
Originally Posted by Nickthedentist View Post
Hello everyone,

I recently got hold of a ~1950 Ericsson N1071A16 wall phone, which is also marked as type H1385, a New Zealand post office designation.

The numbers on the dial are backwards compared with what we're used to, but otherwise it's very similar to the UK variants, which have an almost standard 300-series chassis albeit modified to work in a wall-mounted case, see here: https://www.britishtelephones.com/ericsson/n1071.htm

The dial was a mess (seized clutch and broken return spring) but I've restored everything now and would like to use it at home.

However, there's a catch... this seems to be an instrument re-designed for the NZ telephone system. It has an extra changeover contact on the gravity switch and a separate earth connection. There's also an odd, asymmetrical leaf spring on the bell motor.

I've attached a photo of the paster in mine. You can see it's very similar indeed to the standard GPO 332: https://www.britishtelephones.com/gp...t322paster.jpg

So, to the big question... What do I need to do? Certainly, linking T2-T3 would be a start, connecting the line to the points marked A and B.

Two-wire working would be fine. And obviously, I realise that I'd need to do a bit of mental conversion when dialling!

Thanks, experts,

Nick.

EDIT: Mods, please delete the "party line" bit from the title
Used with 'multi-party' party lines which used code-ringing on Strowger exchanges in NZ.

Quite easy to mod to have an identical circuit to a GPO Tele 332 -
a) Remove the green wire that runs between T1 and Switchhook spring No 3
b) Move the brown wire from T3 to T1
c) Remove the Slate(grey) wire between Dial terminal Strip 2 and Switchhook No 4
d) Remove the Orange wire between T12 and Switchhook 7
e) Strap Dial Terminal strip 2 and 3
f) Strap T11 and 12.

Then your telephone is identical circuit to a Tele 332 except that Switchhook make contacts are No 5 and 6 rather than No 3 & 4 on the Tele 332. Line A wire goes to T1 and B wire to T9 as per Tele 332

Then just go ahead with converting a Tele 332 to three wire as per Bob F's instructions -
Then the telephone is ready to go.

Note the NZ dials are identical to the UK ones except for the fingerplate.
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Old 19th May 2020, 9:38 pm   #4
Nickthedentist
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Thanks Dave for your thoughts, and Ian for your in-depth advice... I tried to work it out for myself, but it made my head hurt. That's amazing, I will have a go later this week.

I willl look up multi-party party lines and code-ringing.

Yes, I thought the dials were identical and have swapped the fingerplate in anticipation, but nice to have it confirmed by someone who knows!

Nick.

Last edited by Nickthedentist; 19th May 2020 at 9:44 pm.
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Old 19th May 2020, 9:44 pm   #5
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Not much to be found except stuff like this:
Quote:
Multi-party ringing. A small and rapidly decreasing proportion of rural lines connected to the Telecom PSTN are multi-party and use a system of code ringing based on the morse code. This type of line is being progressively phased out by Telecom and replaced by individual lines.
Anyone care to elaborate?

Thanks again,

Nick.
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Old 20th May 2020, 1:26 am   #6
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Quote:
Originally Posted by Nickthedentist View Post
Not much to be found except stuff like this:
Quote:
Multi-party ringing. A small and rapidly decreasing proportion of rural lines connected to the Telecom PSTN are multi-party and use a system of code ringing based on the morse code. This type of line is being progressively phased out by Telecom and replaced by individual lines.
Anyone care to elaborate?

Thanks again,

Nick.
The Morse code ringing cadences seems to have a long history in NZ and I presume the same cadences were used after automation.

http://www.awaruamuseum.co.nz/nzpo-e...telephone.html

Party Lines
Initially it was common for more than one customer (subscriber or 'sub') to share a telephone line, particularly in rural areas where for example, one phone line might provide service to all the farms in a valley. There was no privacy on such a line, as all users could hear every ring on the line and by lifting their handset could listen to any other phone call. A system of coded short and long rings was used to identify who a call was for. The shorter Morse Code letters were allocated first, however on 10 party lines the ring codes inevitably were longer. The ring codes used were A, D, M, R and S for a 5-party line. These were extended by using J, K, U, W and X for a 10 party line. Example ring codes for S, M and W were: S was three short rings; M was two long rings; and W was a short followed by two long rings.

Consideration for others was important. For instance, when first picking up the phone a user would say 'Working?' to see if the line was in use. They would limit the length of their call - say to 5 minutes on a line with many subscribers, then at the end of their call would crank their phone 'magneto' - the ring generator - to make a short ring burst on the line advising the operator and all other users that they were finished and the line was available.
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Old 20th May 2020, 5:33 am   #7
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Quote:
Originally Posted by Nickthedentist View Post
Quote:
Multi-party ringing. A small and rapidly decreasing proportion of rural lines connected to the Telecom PSTN are multi-party and use a system of code ringing based on the morse code. This type of line is being progressively phased out by Telecom and replaced by individual lines.
Anyone care to elaborate?
Party lines. On manual exchanges you'd have a number like "123S" and the ring would be an "S" in morse. If you were "123M" you wouldn't answer - unless you were nosy. With automatic exchanges you'd have a normal looking number, but the distinctive ring and shared line remained.

It was only in remote areas - for example my wife grew up in Monowai and they had a party line until the late 80s, on an automatic exchange by that stage and it would have been one of the last areas. The last couple of manual exchanges were gone by then too - funnily enough Queenstown was one of the last.

As far as I'm aware our phone system shouldn't be significantly different to the UKs - BT jacks are still in common use here, and one of the reasons for our emergency number being 111 is because of sharing equipment designed for UK's 999 system. If you google "NZPO type 100" you'll find a very familiar looking device as well....

It might just be me, but I always thought counting from 0-9 made more sense than 0-9...1
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Old 20th May 2020, 12:43 pm   #8
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Default Re: Converting a 1950s Ericsson phone for "normal" working

The dialgizmo may be switched to read reverce pulses, and convert them to DTMF. I have several Oslo telephones and have tested that
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Old 20th May 2020, 1:03 pm   #9
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Quote:
Originally Posted by arjoll View Post
Quote:
Originally Posted by Nickthedentist View Post
Quote:
Multi-party ringing. A small and rapidly decreasing proportion of rural lines connected to the Telecom PSTN are multi-party and use a system of code ringing based on the morse code. This type of line is being progressively phased out by Telecom and replaced by individual lines.
Anyone care to elaborate?
Party lines. On manual exchanges you'd have a number like "123S" and the ring would be an "S" in morse. If you were "123M" you wouldn't answer - unless you were nosy. With automatic exchanges you'd have a normal looking number, but the distinctive ring and shared line remained.

It was only in remote areas - for example my wife grew up in Monowai and they had a party line until the late 80s, on an automatic exchange by that stage and it would have been one of the last areas. The last couple of manual exchanges were gone by then too - funnily enough Queenstown was one of the last.

As far as I'm aware our phone system shouldn't be significantly different to the UKs - <snip>
A lot of the earlier 'Strowger kit was supplied from the UK by the likes of Ericssons & GEC. I have a number of NZPO telephones from 'multi-party' party lines. There were two sorts of party lines. Ones which used 'Simplex Dialling' are the ones I've got. They have both a dial and a magneto generator. They are 'local battery telephones and there would be up to 5 connected across the same line/pair of wires. The Simplex dialling (also used in Saskatchewan in Canada) was an unusual form of dialling. The caller would lift handset and listen and if the line wasn't in use, they would press the 'Call' button which locked in until the handset was replaced. The Call button connected one side of the dial pulsing contacts to earth whilst the other side of the pulsing contact was connected to the centre tap of the AC bell coils. The bell was connected (without a capacitor) across the A and B line wires. It then operated a high speed relay also at a centre tapped point. Caller could then dial out into the rest of the network. As mentioned , incoming calls from the PSTN sent the relevant ring code according to the Morse letter allocated to the called line. Callers on the same multi-party line called each other with a generator using the same Morse code letters.

The other type of party line was a 5 party 'revertive call' line where the caller would dial the code of the required 'party phone' then replace the handset. It used loop dialling rather than the earth 'Simplex' dialling. All the phones would then ring with the relevant code ring. When the person whose code it was answered, the ringing would stop and the caller would lift the phone and they could speak. WE have managed to get the 'multi-party' party line with the S/A/D/M or R code ringing working on CNet with up to five telephones working on an ATA - only works with Linksys ATAs. Luckily I've got hundreds of NZPO circuit diagrams for their Strowger exchanges including the NZ version of the GPO's UAX13.
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Old 20th May 2020, 2:38 pm   #10
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Fantastic, all very interesting stuff, thank you!

Does anyone know what the little spring on the bell motor (post 1, last pic) is for, please?

Nick
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Old 20th May 2020, 2:56 pm   #11
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Could it be to ensure that it always returns to the same rest position regardless of where in the ringing cycle it was stopped? I'll leave others to say why this may be desirable!
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Old 20th May 2020, 2:58 pm   #12
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Default Re: Converting a 1950s Ericsson phone for "normal" working

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Fantastic, all very interesting stuff, thank you!

Does anyone know what the little spring on the bell motor (post 1, last pic) is for, please?

Nick
Anti-bell tinkle probably.
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Old 20th May 2020, 3:03 pm   #13
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Thank you both, the latter had crossed my mind.
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Old 20th May 2020, 3:14 pm   #14
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Default Re: Converting a 1950s Ericsson phone for "normal" working

I was wondering about anti-tinkle, but was thinking the effectivenes would depend upon the polarity of the voltage change causing the tinkle. I suppose, however, if the spring holds the clapper in contact with one gong it couldn't ting against that one, and the resistance of the spring prevents it reaching the other one.
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Old 20th May 2020, 4:20 pm   #15
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Default Re: Converting a 1950s Ericsson phone for "normal" working

I suppose I could experiment...

I'm still intrigued how a 1950s wall-mounted instrument from NZ ended up over here, being sold by a house clearance outlet on eBay.

N.
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Old 20th May 2020, 8:57 pm   #16
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Default Re: Converting a 1950s Ericsson phone for "normal" working

My Bell No 1A has a similar bias spring
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Old 20th May 2020, 9:09 pm   #17
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Default Re: Converting a 1950s Ericsson phone for "normal" working

Well I never, that's interesting.
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Old 20th May 2020, 11:20 pm   #18
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Default Re: Converting a 1950s Ericsson phone for "normal" working

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Originally Posted by Nickthedentist View Post
I suppose I could experiment...

I'm still intrigued how a 1950s wall-mounted instrument from NZ ended up over here, being sold by a house clearance outlet on eBay.

N.
Did it come from Cornwall? I brought quite a few back getting on for twenty years ago. I had a friend (into telephones' since we were at school together in the 1950's!) in Cornwall who sadly passed away about four years ago and his wife had a clearout to a Steve..... who had lots of his Strowger bits and pieces for sale on eBay. It may have come from him?

And there are some NZ Party-line phones still working on a mile long code ringing party line in the UK - on a little island with no mains electricity or flushing toilets! Time has stood still there - the last house there was built 150 years ago! Only three houses are lived in all the year round. Took a long while to install as cabling had to be virtually 'invisible'. Even filmed for a TV program whilst I was installing one of the phones and interviewed for Radio 4 on another trip!
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Old 21st May 2020, 5:36 pm   #19
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Default Re: Converting a 1950s Ericsson phone for "normal" working

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My Bell No 1A has a similar bias spring
I wonder if that spring is anything to with suppressing bell tinkle? I can't think of any other reason for it.
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Old 21st May 2020, 6:50 pm   #20
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Default Re: Converting a 1950s Ericsson phone for "normal" working

That does appear to be the prevailing opinion in this thread.
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