Master socket schematic - UK Vintage Radio Repair and Restoration Discussion Forum

Dr-of-style · 29th Jul 2020, 7:40 pm

Could someone post a schematic for your MASTER, and EXTENSION sockets please?
I am not acquainted with your wiring scheme...yet!

AC/HL · 29th Jul 2020, 7:47 pm

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

Dr-of-style · 29th Jul 2020, 8:47 pm

Thanks

Dave Moll · 29th Jul 2020, 9:52 pm

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)).

russell_w_b · 29th Jul 2020, 10:14 pm

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.

ThePillenwerfer · 30th Jul 2020, 12:11 am

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.

russell_w_b · 30th Jul 2020, 7:48 am

Quote:

Originally Posted by ThePillenwerfer

Terminals 1 and 6 are rarely used and usually aren't even connected up, at least in houses.

I found terms 1 and 6 very handy when I had my magneto / field telephones connected between living room, office and shed when the kids were little.

When I put the wiring in I put in three-pair cable and populated the lot.

Dave Moll · 30th Jul 2020, 8:28 am

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.

russell_w_b · 30th Jul 2020, 9:34 am

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.

Station X · 30th Jul 2020, 9:41 am

You'll find the booklet here:-

https://www.vintage-radio.info/download.php?id=365

russell_w_b · 30th Jul 2020, 9:53 am

Quote:

Originally Posted by Station X

You'll find the booklet here:-

Thanks, Graham - useful to know!

29th Jul 2020, 7:40 pm	#1
Dr-of-style Triode Join Date: Jul 2020 Location: Dallas, Texas, USA. Posts: 11	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
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	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

29th Jul 2020, 8:47 pm	#3
Dr-of-style Triode Join Date: Jul 2020 Location: Dallas, Texas, USA. Posts: 11	Re: Master socket schematic Thanks

29th Jul 2020, 9:52 pm	#4
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,127	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)). __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

29th Jul 2020, 10:14 pm	#5
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	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. __________________ Regds, Russell W. B. G4YLI.

30th Jul 2020, 12:11 am	#6
ThePillenwerfer Octode Join Date: Mar 2011 Location: Sheffield, South Yorkshire, UK. Posts: 1,453	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. Attached Thumbnails __________________ "Experts are only good at one thing: explaining why something will not work!" Last edited by ThePillenwerfer; 30th Jul 2020 at 12:20 am.

30th Jul 2020, 8:28 am	#8
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,127	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. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

30th Jul 2020, 9:34 am	#9
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	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. Attached Thumbnails __________________ Regds, Russell W. B. G4YLI.

30th Jul 2020, 9:41 am	#10
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,286	Re: Master socket schematic You'll find the booklet here:- https://www.vintage-radio.info/download.php?id=365 __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.