Old phone no ring - UK Vintage Radio Repair and Restoration Discussion Forum

Jimmyspurls · 23rd Mar 2023, 12:04 pm

Hello I bought a lovely old phone which works a great but does not ring when in coming calls are made. It has Farnborough Air Show stamped on it so I believe the ring would have been sent to a remote external bell. How do I rewire it? There are some vids on YouTube but they don't match my phone. I've added a pic of the inside. Any help much appreciated. Jim

Nickthedentist · 23rd Mar 2023, 12:14 pm

Hello and welcome.

This should be simple to sort through out, but to help you, please post another pic like your third one but with the cables’ square grommets slid out sideways from the metal brackets, so that we can see the wires and terminals more clearly.

Dave Moll · 23rd Mar 2023, 12:56 pm

There doesn't appear to be a connection between T17 (bell return) and T18 ("A" leg of line) though, as Nick says, it's a struggle to see what wires go where and an image with the grommets withdrawn would help.

ThePillenwerfer · 23rd Mar 2023, 1:18 pm

This is how things should be connected up. The resistor doesn't really matter so just replace it with a 'strap' — as the bits of metal that connect adjacent terminals together are known.

Jimmyspurls · 23rd Mar 2023, 4:03 pm

Thanks all here's some more pics.

Pic

Oldcodger · 7th Apr 2023, 5:33 pm

Jimmy, Im not conversant with this model, but if you GOOGLE N diagrams by Sam Halls, you will find a list of PO TYPE circuits. Most possibly the best example is type 706 ( diagram 806) which shows you how the bell circuit is laid out and other connections.
On the old ( pre plug system) , with one phone, ringing volts entered via one leg of line and went through a capacitor ( usually 1.8/2uF ) via bell and back to line on the other leg of line.
These days on modern jack systems, the phone capacitor is redundant ( and indeed having two capicitors in the circuit can cause ring trip , where phone rings once and answers call) as the capicitor on the master socket provides this function.
On PO 700 TYPE PHONES ,the bell( on older models) was 2x 500 ohm coils. This has to be increased to work on the plug system to circa 3500 ohms.
Hope thats helpfull.

Dave Moll · 7th Apr 2023, 10:24 pm

I can't see anything saying what model this is, but assuming it to be a 756 (push-button LD dialling powered from the telephone line), I would suggest wiring it according to https://www.britishtelephones.com/pstconv1.htm#700 and see whether this solves your problems.

Pellseinydd · 8th Apr 2023, 3:41 pm

Quote:

Originally Posted by Jimmyspurls

Thanks all here's some more pics.

Pic

Put Blue from Line cord presently on Terminal 15 onto Terminal 6 Remove strap between T7 & T6 and use to strap T5 & T6 so that T 4,5 & 6 are strapped.

Green from Line cord should go onto T15 (which is a spare terminal wired to nowhere!) and not T 17 as is.

Red from Line cord to T8 as is.

White from Line cord to T18 (as is) with a Strap (piece of bare wire) between T17 and T18.

This assumes it is a GPO Telephone 756 modified to an 8756 for modern plug and socket working. However the colours of the wire to the tone dialling unit don't match up with those on the GPO/PO N diagram

Photo of underside of the base would help to establish the model as it may not be a GPO/PO/BT version of the phone.

Hope that works.
Ian J

Oldcodger · 11th Apr 2023, 1:45 pm

EDIT - #6 for Jimmy. Sam Hall should read Sam Hallis.
#7/#8 , problem is working out technical capabilities of posters. Like you ( and possibly a few others , I spent a few years at GPO training schools having the theory of handsets force fed) , so I posted #6 to perhaps him see what a simple telephone internal wiring should look like.
It's what we learned as a rote in our apprentice days.

23rd Mar 2023, 12:04 pm	#1
Jimmyspurls Diode Join Date: Mar 2023 Location: Ipswich, Suffolk, UK. Posts: 2	Old phone no ring Hello I bought a lovely old phone which works a great but does not ring when in coming calls are made. It has Farnborough Air Show stamped on it so I believe the ring would have been sent to a remote external bell. How do I rewire it? There are some vids on YouTube but they don't match my phone. I've added a pic of the inside. Any help much appreciated. Jim Attached Thumbnails

23rd Mar 2023, 12:14 pm	#2
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,560	Re: Old phone no ring Hello and welcome. This should be simple to sort through out, but to help you, please post another pic like your third one but with the cables’ square grommets slid out sideways from the metal brackets, so that we can see the wires and terminals more clearly.

23rd Mar 2023, 12:56 pm	#3
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,050	Re: Old phone no ring There doesn't appear to be a connection between T17 (bell return) and T18 ("A" leg of line) though, as Nick says, it's a struggle to see what wires go where and an image with the grommets withdrawn would help. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

23rd Mar 2023, 1:18 pm	#4
ThePillenwerfer Octode Join Date: Mar 2011 Location: Sheffield, South Yorkshire, UK. Posts: 1,453	Re: Old phone no ring This is how things should be connected up. The resistor doesn't really matter so just replace it with a 'strap' — as the bits of metal that connect adjacent terminals together are known. Attached Thumbnails __________________ "Experts are only good at one thing: explaining why something will not work!"

23rd Mar 2023, 4:03 pm	#5
Jimmyspurls Diode Join Date: Mar 2023 Location: Ipswich, Suffolk, UK. Posts: 2	Re: Old phone no ring Thanks all here's some more pics. Pic Attached Thumbnails

7th Apr 2023, 5:33 pm	#6
Oldcodger Nonode Join Date: Oct 2014 Location: West Midlands, UK. Posts: 2,176	Re: Old phone no ring Jimmy, Im not conversant with this model, but if you GOOGLE N diagrams by Sam Halls, you will find a list of PO TYPE circuits. Most possibly the best example is type 706 ( diagram 806) which shows you how the bell circuit is laid out and other connections. On the old ( pre plug system) , with one phone, ringing volts entered via one leg of line and went through a capacitor ( usually 1.8/2uF ) via bell and back to line on the other leg of line. These days on modern jack systems, the phone capacitor is redundant ( and indeed having two capicitors in the circuit can cause ring trip , where phone rings once and answers call) as the capicitor on the master socket provides this function. On PO 700 TYPE PHONES ,the bell( on older models) was 2x 500 ohm coils. This has to be increased to work on the plug system to circa 3500 ohms. Hope thats helpfull.

7th Apr 2023, 10:24 pm	#7
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,050	Re: Old phone no ring I can't see anything saying what model this is, but assuming it to be a 756 (push-button LD dialling powered from the telephone line), I would suggest wiring it according to https://www.britishtelephones.com/pstconv1.htm#700 and see whether this solves your problems. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

11th Apr 2023, 1:45 pm	#9
Oldcodger Nonode Join Date: Oct 2014 Location: West Midlands, UK. Posts: 2,176	Re: Old phone no ring EDIT - #6 for Jimmy. Sam Hall should read Sam Hallis. #7/#8 , problem is working out technical capabilities of posters. Like you ( and possibly a few others , I spent a few years at GPO training schools having the theory of handsets force fed) , so I posted #6 to perhaps him see what a simple telephone internal wiring should look like. It's what we learned as a rote in our apprentice days.