old telephone wire colours

sarahproperty · 27 May 2007

i am trying to connect the cable from an old telephone (bt 746) to the cable which has an end on which can slot into the socket on the wall (i think this might be a jack?).

i do not wish to hard wire this phone into the wall.

the colours on the telephone wire are red green blue and white

the colours on the end jack are yellow green black and red.

does anyone know which colours should be crimped together?

many thanks

securespark · 27 May 2007

Need pictures really.

sarahproperty · 27 May 2007

i dont know how to attach photos. where is the button to let you attach photos? thanks
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breezer · 27 May 2007

sarahproperty said:
i dont know how to attach photos. where is the button to let you attach photos? thanks
[/img]

are not forums amazing? there is a whole bunch of information available , all you have to do is look.

picture information is clicky and this post should be clicky

i have also pressed the alert mods button asking for it to be moved

sarahproperty · 27 May 2007

woh, there is no way i can manage that, i havent got a wesite address anyway.

breezer · 27 May 2007

sarahproperty said:
woh, there is no way i can manage that, i havent got a wesite address anyway.

you did not read it very well then.

nil point

TicklyT · 27 May 2007

http://web.ukonline.co.uk/freshwater/pstconv1.htm may be useful

Chri5 · 27 May 2007

sarahproperty said:
i am trying to connect the cable from an old telephone (bt 746) to the cable which has an end on which can slot into the socket on the wall (i think this might be a jack?).

i do not wish to hard wire this phone into the wall.

the colours on the telephone wire are red green blue and white

the colours on the end jack are yellow green black and red.

does anyone know which colours should be crimped together?

many thanks

746 phones were hard wired and contain a capacitor. There is a conversion for turning them into LJU phones by moving the straps inside the phone and fitting the 4w spade connectors.

We need an N diagram, since it's been 23 years since I did any.

746 might look twee but they are dial pulse phones not MF dialling and bell tinkle was always an issue when you have 2 or 3 phones around the house.

Here's the N diagram http://www.samhallas.co.uk/repository/n_diagrams/0000/N846.pdf

Lectrician · 27 May 2007

Bell tinkle wont be a problem if she removes internal capacitor, and wires the phone to the jack using pin 3 for ringer......thats why we have pin 3, a legacy to the old phones with the bell - to stop the tinkle!

bernardgreen · 27 May 2007

Lectrician said:
Bell tinkle wont be a problem if she removes internal capacitor, and wires the phone to the jack using pin 3 for ringer......thats why we have pin 3, a legacy to the old phones with the bell - to stop the tinkle!

Not quite the reason for pin 3 supplying the bells.

Wire 3 connects all bells and / or sounders to a single capacitor. This is the more efficient way to operate bells / sounders.

Lectrician · 27 May 2007

bernardgreen said:
Lectrician said:

Bell tinkle wont be a problem if she removes internal capacitor, and wires the phone to the jack using pin 3 for ringer......thats why we have pin 3, a legacy to the old phones with the bell - to stop the tinkle!

Click to expand...

Not quite the reason for pin 3 supplying the bells.

Wire 3 connects all bells and / or sounders to a single capacitor. This is the more efficient way to operate bells / sounders.

NO. This is the way they found it was easiest to prevent tinkle on other phones when ending a call.

Chri5 · 27 May 2007

Lectrician said:
Bell tinkle wont be a problem if she removes internal capacitor, and wires the phone to the jack using pin 3 for ringer......thats why we have pin 3, a legacy to the old phones with the bell - to stop the tinkle!

Bell tinkle won't be a problem if the rest of the house has MF phones

When wiring up plan 1A's anti tinkle was important due to dial pulse on another phone causing the tinkle. Since LJU's the pin 3 is the bell / ring wire, 2 znd 5 the line and 4 for ER on non TBR PABX's

While on the subject, I remember (vaguely) fitters using a thermistor to kill the tinkle when 746's were adapted for LJU's due to the ringer being the wrong resistance- OR WAS that a DREAM ???

bernardgreen · 28 May 2007

Chri5 said:
While on the subject, I remember (vaguely) fitters using a thermistor to kill the tinkle when 746's were adapted for LJU's due to the ringer being the wrong resistance- OR WAS that a DREAM ???

Not a dream

Also the bells on original plans were connected in series and were low impedance circa 1000 ohms (2 off 500 ohm windings ). On modern plug plans the bells are in parallel with each other and should be at least 4000 ohms impedance.

There are now bells with 2 off 2000 ohm windings series connected for plug plans and parallel for old style plans.

TicklyT · 28 May 2007

A 3K resistor in series with low impedance bell coils can improve things as far as the REN (Ringer Equivalence Number) value is concerned. Without it, a modified 706 / 746 was considered to have a REN of 4, but adding it reduces it to something nearer to 1. The total of all the REN numbers isn't supposed to exceed 4, IIRC

One of the springsets (on the dial IIRC) was supposed to short out the bell circuit during dialling to prevent tinkle.

If you use ADSL, some filters don't connect pin 3 to the socket, deriving a bell circuit from an internal capacitor instead, so you can end up with bell tinkle everywhere if you use a dial phone.

JHandyman · 17 Jul 2011

As far as I can remember, A thermistor was only designed to be used on shared service (party) lines to prevent bell tinkle on the party not in use. On a non party line, lifting the hsndset disconnected the series bell circuit. Fitting a thermistor on a non party line was an unofficial "fix" to get around a faulty or mis wired circuit. ( but it was easier than finding the fault...)

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old telephone wire colours

breezer

breezer

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