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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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29th Jul 2020, 7:40 pm | #1 |
Triode
Join Date: Jul 2020
Location: Dallas, Texas, USA.
Posts: 11
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Master socket schematic
Could someone post a schematic for your MASTER, and EXTENSION sockets please?
I am not acquainted with your wiring scheme...yet! |
29th Jul 2020, 7:47 pm | #2 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,643
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Re: Master socket schematic
This is how they're wired. The sockets are the same, but the master is the only one with the ringing capacitor: http://www.telephonesuk.co.uk/wiring_info.htm
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29th Jul 2020, 8:47 pm | #3 |
Triode
Join Date: Jul 2020
Location: Dallas, Texas, USA.
Posts: 11
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Re: Master socket schematic
Thanks
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29th Jul 2020, 9:52 pm | #4 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,130
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Re: Master socket schematic
I find the diagram in the telephonesuk link rather misleading, given that the capacitor in the master goes between terminals 2 and 3 of the socket - usually along with a resistor between 3 and 5 and a surge protector between 2 and 5. Terminals 1, 4 and 6 normally being unused. Bob Freshwater's page gives a clearer idea (the numbering marked jack 601a being that used for the plug (431a or 631a)).
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29th Jul 2020, 10:14 pm | #5 |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
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Re: Master socket schematic
Simply put, the incoming line pair is routed across all telephone speech networks and dialling pulses (I'm talking 'traditional' telephones here).
All the bells on all the telephones are connected in parallel, via one series capacitor located in the master box. The return leg for the bells is the line opposite the one the capacitor leads from. The cap is 1u8 and is used to keep the d.c. loop off the bells. This third wire also shunts the bells when dialling so the others don't 'tinkle'. In the old days all bells were wired in series through one capacitor located in one of up to six extensions. Modern electronic telephones just use two wires with electronic signalling.
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30th Jul 2020, 12:11 am | #6 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Master socket schematic
Below is a diagram of a Master Socket.
The resistor is for testing purposes as it's possible for no 'phone to be connected when this is done. Terminals 1 and 6 are rarely used and usually aren't even connected up, at least in houses. Terminal 4 could be used for Earth but the only time that would be needed on a domestic line was if it was Shared Service, ie a Party Line. I don't know for sure but I'd doubt if there were many, if any, of those remaining by the time this type of plug and socket was introduced. The only other time an Earth would be needed was on private switchboards that used Earth Break Recall. Just to really confuse things the corresponding plugs are numbered the other way, ie plug terminal 5 connects to socket terminal 2, 4 to 3, 3 to 4 and 2 to 5. Last edited by ThePillenwerfer; 30th Jul 2020 at 12:20 am. |
30th Jul 2020, 7:48 am | #7 | |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
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Re: Master socket schematic
Quote:
When I put the wiring in I put in three-pair cable and populated the lot.
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Regds, Russell W. B. G4YLI. |
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30th Jul 2020, 8:28 am | #8 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
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Re: Master socket schematic
Yes, it makes a useful pair for alternative purposes. In one instance where three-pair cabling had been used between the master (near the front door) and slave (in the upstairs office), we used the third pair for the door bell.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
30th Jul 2020, 9:34 am | #9 |
Dekatron
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Location: Penrith, Cumbria, UK.
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Re: Master socket schematic
According to the 'Phone Socket' manual, published when the system was introduced, the fifth and sixth wires 'will be used for other non-telephone facilities. The main advantage of installing six wire initially is that future telephone modifications or new systems can be introduced without extensive rewiring. All new telephones will have high-impedance ringing devices.'
Attached is (yet) another drawing of how the master / slaves are connected. Incidentally... Reading through the booklet, under the section 'Ringing Device Arrangement', it says:- 'Low impedance telephones in the Trimphone range may be modified to high impedance by connecting a 3.3K resistor in series with its phone caller (ie: between T4 and T5). Low impedance telephones in the 8700 series may be modified to high impedance by the substitution of a Bell 59D-1 unmounted for the existing low impedance bell coil' Nothing about banging a 3.3k resistor in a telephone with 1000 Ohm bell movement! It was a replace-bell job: 4000 Ohm in, 1000 Ohm out. This publication was an official Installer guide when the Phone Socket scheme was introduced.
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Regds, Russell W. B. G4YLI. |
30th Jul 2020, 9:41 am | #10 |
Moderator
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Location: Ipswich, Suffolk, IP4, UK.
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Re: Master socket schematic
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
30th Jul 2020, 9:53 am | #11 |
Dekatron
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Location: Penrith, Cumbria, UK.
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Re: Master socket schematic
Thanks, Graham - useful to know!
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Regds, Russell W. B. G4YLI. |