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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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24th Sep 2018, 12:52 pm | #1 |
Retired Dormant Member
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Old telephone won't ring
Hi there,
I hope I am posting this in the appropriate place. I have a 1981 British dial telephone, which works fine but does not ring (here in Belgium). Apparently the voltage on the Belgian phone network is too low. Is it possible to 'boost' it somehow? Many thanks, Kevin |
24th Sep 2018, 2:00 pm | #2 |
Dekatron
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Re: Old telephone won't ring
Are you sure it's a matter of line voltage? It may be that ringing is via a third wire (usually coloured blue if the line wires are red and white). The ringing voltage is applied to this wire via a capacitor of up to 1.8μF from the "B" leg (usually red) of the line. In the UK this is achieved either by use of a master socket containing the appropriate components or by an ADSL microfilter (most UK ones including a ringer capacitor).
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24th Sep 2018, 2:17 pm | #3 |
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Re: Old telephone won't ring
Thank you, Dave. So It may down to the socket then? The ringer does work because it was tested in the antiques shop the other week when I bought it. All I've done is plug the original phone plug into an adapter that fits the Belgian wall socket.
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24th Sep 2018, 3:16 pm | #4 |
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Re: Old telephone won't ring
Please post a picture of the insides of the phone, showing how the wires are connected to the circuit board.
Nick. |
24th Sep 2018, 4:14 pm | #5 |
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Re: Old telephone won't ring
Thanks.
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24th Sep 2018, 5:43 pm | #6 |
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Re: Old telephone won't ring
That looks like a Telephone 746 or 8746, and since there are no connections to terminals T7 and T9, you do need an external ringing capacitor.
There are 2 things you could try : 1) Disconnect the blue wire of the line cord. Connect terminal T9 to T8 (leaving the existing wiring on T8 alone) and T7 to T6 (again leaving the existing wiring and jumpers alone). 2) Get a UK _Master_ telephone socket. Connecter terminals 2 and 5 inside the socket to your telephone line. Plug the UK telephone in (without changing any internal wiring). |
24th Sep 2018, 6:29 pm | #7 |
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Re: Old telephone won't ring
If you go for this option, you could park it on one of the unused terminals from T11 to T14.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
24th Sep 2018, 7:30 pm | #8 |
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Re: Old telephone won't ring
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24th Sep 2018, 9:08 pm | #9 |
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Re: Old telephone won't ring
I think in this instance the problem is that it is converted for three-wire working and needs to be reverted to the original two-wire state.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) Last edited by Dave Moll; 24th Sep 2018 at 9:12 pm. Reason: reworded for clarification |
24th Sep 2018, 9:47 pm | #10 |
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Re: Old telephone won't ring
yes, quite. Has anyone got a pic of the original configuration?
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25th Sep 2018, 4:33 am | #11 |
Octode
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Re: Old telephone won't ring
I haven't got a picture but here's a diagram.
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25th Sep 2018, 7:08 am | #12 |
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Re: Old telephone won't ring
Hi
As you understand the GB wiring standard is different than most other countries, that makes rewiring or converting a common issue. For us non GB people it will sometimes include adding parts as a capacitor who has the function of just letting ring current pass to the ringer. In GB plug and socket system the capacitor is located in the socket. Your phone may have the capacitor, or may not. First try should be to put a wire or link between T6- and T7 and try. You also need connections between T9-T9 (missing on picture) and between T16-T17-T18-T19 (looks right on the picture) Give it a try. The Belgian ringing voltage should be at least 60V and that should be enough. (It may be 90 as in GB too) dsk |
25th Sep 2018, 10:22 am | #13 |
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Re: Old telephone won't ring
Thank you guys. I wired it according to the diagram - the green and red were already in place - but still no jolly ringing.
Kevin |
25th Sep 2018, 11:45 am | #14 |
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Re: Old telephone won't ring
I think a photo of how you now have it wired would be helpful, so that we can check that everything is correct.
Also, if you have a multimeter, it would be a good idea to check the resistance of the bell motor (T4 to T16), which should be approximately either 1,000Ω or 4,000Ω (depending on its age).
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25th Sep 2018, 3:22 pm | #15 |
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Re: Old telephone won't ring
Thanks. I believe it dates from 1981.
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25th Sep 2018, 8:37 pm | #16 |
Octode
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Re: Old telephone won't ring
Hi, the first thing you need to do is to ensure that there is a capacitor in the C1 position next to the gravity switch at the right of the phone looking from the rear (it looks like it is present from your picture)
Assuming that you are using some kind of adapter to allow you to use a British BT plug on your country's phone socket re-wire/strap the phone as follows. Strap T4 - T5 - T6 - T7 Strap T8 - T9 Strap T16 - T17 - T18 - T19 If you don't have enough straps you can just use wire links Park the Green and Blue leads of your line cord on T14 and T15 (it doesn't matter which way round they are) Red of line cord to T8 White of line cord to T18 Try that and let us know Regards Andrew |
25th Sep 2018, 9:07 pm | #17 |
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Re: Old telephone won't ring
Have you a multimeter? Can you actually measure the a.c. voltage on the bell coils when it's meant to be ringing? What's to say the bell hasn't gone O/C or simply developed a mechanical fault between it ringing successfully earlier and now? Or you have a duff adaptor?
Is the hammer and armature free to move?
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25th Sep 2018, 9:53 pm | #18 |
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Re: Old telephone won't ring
You need to join T6 and T7 together and T9 to T10. You don't need proper 'straps;' bits of wire or paper-clips will do. Other than that it looks right.
I've marked what I mean in red on your picture. By the way, it's 1979 vintage. There does indeed seem to be a capacitor (the white block) in the C1 position in your photograph in Post 5. Last edited by ThePillenwerfer; 25th Sep 2018 at 10:11 pm. |
26th Sep 2018, 9:47 am | #19 |
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Re: Old telephone won't ring
That should read "T8 to T9" - as shown in the photo.
By the way, it may be a good idea to point the spade on the blue linecord lead the other way so that avoids the risk of fouling the connections on the row above.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) Last edited by Dave Moll; 26th Sep 2018 at 9:52 am. Reason: blue lead |
26th Sep 2018, 10:50 am | #20 |
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Re: Old telephone won't ring
Marvellous. Thank you so much, gentlemen, ThePillenwerfer's solution works. It's not as loud as the ring in the UK but still quite audible. I didn't have anything as technical as a paper clip here to do the strapping but a piece of old guitar string has done the trick.
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