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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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5th Oct 2019, 2:51 pm | #1 |
Pentode
Join Date: Dec 2015
Location: Abingdon on Thames, Oxon, UK.
Posts: 116
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706 telephone conversion
I have decided to sell off some of my collection of cherished instruments including some 700 series phones. I have modified them as per instructions found in this forum, but cannot get any to ring. I know the "bell" wire was disconnected at the master socket to improve ADSL performance some years ago so it's now just the two wires, so can anyone direct me to the correct links to make in the 706 and 746 types?
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5th Oct 2019, 3:21 pm | #2 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: 706 telephone conversion
If you're selling them as leave them as they are as they are 'correct.'
If you want to use one yourself on two wires see attached. You'll only need to change one. |
5th Oct 2019, 4:01 pm | #3 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,225
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Re: 706 telephone conversion
What I do for 2-wire 706s and 746s is wire them exactly as in the appropriate N diagram (N806, N846) including the original line cord. I terminate that in a Block Terminal 52 (the original junction box) and fit a 3k3 resistor in place of the strap for the extension bell there (which puts that resistor in series with the 1k bell in the telephone). Then wire the 2 line wires to the appropriate terminals in the Block Terminal.
That is, wire as the N diagram, connect a 3k3 resistor between the white and green wires of the line cord and connect the line wires to the white and red wires of the line cord. This has the advantage that the telephone is absolutely 'as original' inside. |
5th Oct 2019, 9:14 pm | #4 | |
Heptode
Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 805
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Re: 706 telephone conversion
Quote:
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7th Oct 2019, 2:36 pm | #5 |
Pentode
Join Date: Dec 2015
Location: Abingdon on Thames, Oxon, UK.
Posts: 116
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Re: 706 telephone conversion
Thanyou for the good advice. Since my original posting I have plugged some of my phones (the ones with BT plugs) into the Master Socket and they ring, but not in extensions. I'll try the broadband filter idea.
Now, our phone service is delivered by Virgin Media fibre and there is something I have always wondered, how does a fibre system produce ringing current? There is no mains connection that I can see indoors so it must come along the coax from the green box outside. |
7th Oct 2019, 8:09 pm | #6 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: 706 telephone conversion
Virgin actually run two cables: a COPPER co-ax one for broadband and TV and a twisted-pair for telephone. Their talk about fibre is simply marketing bull as that only goes to the street cabinet and it's copper from there to your house.
I believe that they are changing how they do things on new installations but this is how mine was that was installed five years ago and every other that I've actually set eyes on. |
7th Oct 2019, 8:33 pm | #7 |
Octode
Join Date: Aug 2005
Location: Saltburn-East, Cleveland, UK.
Posts: 1,786
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Re: 706 telephone conversion
It doesn't, as has already been mentioned Virgin Media's legacy services are what is known as a HFC network (look it up on Wikepedia) the fibre trunk is long haul into an area and after that the conversion to copper is done at one of the larger street cabinets which then feeds a number of smaller cabinets that have individual copper "drop" cables to the customer premise, originally this was done using Siamese cable which had coax for the broadband and tv services and twisted pair copper for the telephone.
Virgin have now introduced "fibre to home" where the fibre is fed from the street cabinet to the outside of the customer premise, the conversion to copper being done at the external termination box - this means that the telephone service has to be provided via the broadband hub using VOIP principles - from the 29th March this year all new telephone installations have been provided via the broadband service and there are plans to eventually migrate existing customers over to "voice over glass" this will take a number of years though. So even a fibre to home service is still HFC once it is inside the customer premise. It will be some time before the fibre trunk goes direct in to the broadband hub and it will still be the circuitry in the hub which provides ringing current and power for speech. Regards Andrew |
13th Oct 2019, 5:46 pm | #8 |
Pentode
Join Date: Dec 2015
Location: Abingdon on Thames, Oxon, UK.
Posts: 116
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Re: 706 telephone conversion
Thank you for the explanation, I can see further research is needed as I just like to know the technologies behind every connection to my house! There is a small cabinet just outside and they brought a coax cable (RG59) from there through the wall, which was split off to slightly better looking cable to the TV and router.
Cheers Ken |