GPO Jack unit 1B - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Sparks · 17th Mar 2017, 4:59 pm

No bell at all Dave.

I've just finished wiring as per Pell's instructions and diagram and I'm still no further forward. With this jack unit, the problems start as soon as the hook switch wiring comes in, i.e. reduced sidetone volume and failure of switch to kill the line when pressed. As of now, the unit is back in its original configuration with a standalone handset plugged in. It works fine without any switches. Mystery !

TonyDuell · 17th Mar 2017, 5:24 pm

This is probably more than you want to do, but if it were mine...

I'd start by removing the PCB so I could see both sides. Then I'd trace out the connections. It's going to be based on the 746 circuit (the induction coil, rectifier stack (the green thing with 9 connections), regulator lamps and R's and C's look to be the ones found in a 746), so N846 is going to give you a clue. Be warned that the induction coil pins are not numbered in any logical pattern, there are 6 pins, one is not used, they are numbered 1-5 on the N diagrams, but it's not 'down one side and up the other' or anything logical on the actual coil. I think it would take me about an hour to do it, but then I've done this sort of thing many times...

Having then got an accurate circuit for the Jack Unit, I think it will be quite easy to see how to connect it up.

Pellseinydd · 17th Mar 2017, 10:38 pm

The PCB in the Jack Unit 1B is not the same circuit as the one in the Tele 746.

The board in the Jack Unit 1B is a 'Telephone Unit D93093; whereas that in the Tele 746 is a 'Telephone Unit D92732' - similar looking but not quite the same.

The D93093 is only used in the Tele 787 as far as I can see in addition to its use in the Jack Unit 1B.

One other thought - is the 'pendant' telephone actually a 'Telephone No 713' or is it the other version known as a 'Telephone N4455' ? They both look the same externally but the terminal arrangements are different as the N4455 has four sets of make before break contacts which would 'mess things up' if using the terminal arrangements of a Tele 713.

Dave Moll · 18th Mar 2017, 8:32 am

As it happens, this unit is also currently being discussed in the Telephone Heritage Group Yahoo group, where a pointer has been given to the correct circuit diagram - in case it helps to clarify matters. This does, however, only show the unit wired for a straight telephone handset, and I see no provision for a cradle (or gravity) switch.

As Mr Sparks has already noted, this circuit does not include a ringer.

JohnBHanson · 18th Mar 2017, 9:28 am

Connect T4 on 713 to T20 on Jack Unit, Connect T5 on 713 to T19 on Jack Unit - remove link T19 to T20. This gives you the off hook switch.

Now to connect the handset on the 713...
Connect T9 on 713 to T10 on Jack Unit
Connect T8 on 713 to T13 on Jack Unit
Connect T1 on 713 to T5 on Jack Unit
Connect T7 on 713 to T1 on Jack Unit

For bell tinkle supression - only necessary if you fit a dial
T2 on 713 connects to T7 on 713 and blue wire from line cord

Connect line cord as follows:-
Line cord - connect White to T18, Red to T9

JohnBHanson · 18th Mar 2017, 9:29 am

If you need a ringer connect between blue and white of line cord. (Add a 3.3kOhm resistor in series if you are using a 500Ohm bell. (This is normally marked on the coils).

Sparks · 18th Mar 2017, 12:16 pm

Very many thanks everyone. I have also received some advice from Sam Hallas. I'll crack.on as soon as I can and hope for the best.

Sparks · 18th Mar 2017, 5:09 pm

Success at last folks. However, I have to say the successful solution came courtesy of Sam Ballad and the THG. Nevertheless, a big thankyou to everyone on here who has offered advice and possibilities. I'm very grateful.

JohnBHanson · 18th Mar 2017, 5:13 pm

Can you post the successful solution here please - thanks

Sparks · 18th Mar 2017, 8:10 pm

I decided to use a standalone handset and plug it into the 84a socket.

There is a resistor T5 and T6. I think it's 3.3K.

T6 and T7 strapped.

T20 and T19 wire linked.

T10, T11 and T12 strapped. T12 wire linked to T9.

T13 and T14 strapped. T13 wire linked to T17.

T16 and T17 strapped.

Line cord red to T8, white to T18, blue to T6 and green to
T15.

T8 to T9 and T18 to T19 straps removed. Two hook switches will go here instead.

Regulator 6B will fit between T11 and T17.

Obviously no guarantee this configuration will work for everyone !

Pellseinydd · 18th Mar 2017, 8:17 pm

The circuit in message 15 works - it is the circuit of the Tele 787 modified to remove the coinbox elements. Bell only added if needed.

I've just set it up as per the circuit in Msge 15 with a Tele 713 and a Jack Unit 1B - luckily I had some Tele 713s and Jack Units 1B in the 'Stores'

. And it worked first time.

Dialling tone loud and clear on lifting the handset.

Replaced handset and dialled into the circuit the Tele 713/Jack Unit1B was fitted to and it rang out until I lifted the T713's handset and was able to speak between the two phones.

Sparks · 18th Mar 2017, 8:22 pm

Very good Pell. I must have got my wires crossed if mine failed back then. Still, the more the merrier.

Sparks · 19th Mar 2017, 5:45 am

Pell, if yours is still built would you mind posting a photograph of the Jack unit so I can see the straps, wiring etc. Thankyou.

Pellseinydd · 19th Mar 2017, 5:07 pm

See attached. Otherwise PM me and I'll send better copies as I'm limited to what I can send via the forum.

regards

Sparks · 20th Mar 2017, 5:54 am

Pell, there is a PM for you.

Sparks

Pellseinydd · 20th Mar 2017, 5:46 pm

Hi Sparks

Replied direct. I'm sure we'll crack it and let everyone know what the problem was.

Sparks · 8th Apr 2017, 11:03 am

Eventually finished up with a functional 1B jack unit. It serves the red handset and yellow 713 in these pictures. The red lever key is the hookswitch. The black G handset on the left is on a different system altogether. The Sterdy
door phone unit on the right isn't doing anything just yet and is purely decorative.

17th Mar 2017, 4:59 pm	#21
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B No bell at all Dave. I've just finished wiring as per Pell's instructions and diagram and I'm still no further forward. With this jack unit, the problems start as soon as the hook switch wiring comes in, i.e. reduced sidetone volume and failure of switch to kill the line when pressed. As of now, the unit is back in its original configuration with a standalone handset plugged in. It works fine without any switches. Mystery !

17th Mar 2017, 5:24 pm	#22
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: GPO Jack unit 1B This is probably more than you want to do, but if it were mine... I'd start by removing the PCB so I could see both sides. Then I'd trace out the connections. It's going to be based on the 746 circuit (the induction coil, rectifier stack (the green thing with 9 connections), regulator lamps and R's and C's look to be the ones found in a 746), so N846 is going to give you a clue. Be warned that the induction coil pins are not numbered in any logical pattern, there are 6 pins, one is not used, they are numbered 1-5 on the N diagrams, but it's not 'down one side and up the other' or anything logical on the actual coil. I think it would take me about an hour to do it, but then I've done this sort of thing many times... Having then got an accurate circuit for the Jack Unit, I think it will be quite easy to see how to connect it up.

17th Mar 2017, 10:38 pm	#23
Pellseinydd Heptode Join Date: Jul 2007 Location: Flintshire, UK. Posts: 707	Re: GPO Jack unit 1B The PCB in the Jack Unit 1B is not the same circuit as the one in the Tele 746. The board in the Jack Unit 1B is a 'Telephone Unit D93093; whereas that in the Tele 746 is a 'Telephone Unit D92732' - similar looking but not quite the same. The D93093 is only used in the Tele 787 as far as I can see in addition to its use in the Jack Unit 1B. One other thought - is the 'pendant' telephone actually a 'Telephone No 713' or is it the other version known as a 'Telephone N4455' ? They both look the same externally but the terminal arrangements are different as the N4455 has four sets of make before break contacts which would 'mess things up' if using the terminal arrangements of a Tele 713.

18th Mar 2017, 8:32 am	#24
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,127	Re: GPO Jack unit 1B As it happens, this unit is also currently being discussed in the Telephone Heritage Group Yahoo group, where a pointer has been given to the correct circuit diagram - in case it helps to clarify matters. This does, however, only show the unit wired for a straight telephone handset, and I see no provision for a cradle (or gravity) switch. As Mr Sparks has already noted, this circuit does not include a ringer. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

18th Mar 2017, 9:28 am	#25
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 661	Re: GPO Jack unit 1B Connect T4 on 713 to T20 on Jack Unit, Connect T5 on 713 to T19 on Jack Unit - remove link T19 to T20. This gives you the off hook switch. Now to connect the handset on the 713... Connect T9 on 713 to T10 on Jack Unit Connect T8 on 713 to T13 on Jack Unit Connect T1 on 713 to T5 on Jack Unit Connect T7 on 713 to T1 on Jack Unit For bell tinkle supression - only necessary if you fit a dial T2 on 713 connects to T7 on 713 and blue wire from line cord Connect line cord as follows:- Line cord - connect White to T18, Red to T9

18th Mar 2017, 9:29 am	#26
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 661	Re: GPO Jack unit 1B If you need a ringer connect between blue and white of line cord. (Add a 3.3kOhm resistor in series if you are using a 500Ohm bell. (This is normally marked on the coils).

18th Mar 2017, 12:16 pm	#27
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B Very many thanks everyone. I have also received some advice from Sam Hallas. I'll crack.on as soon as I can and hope for the best.

18th Mar 2017, 5:09 pm	#28
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B Success at last folks. However, I have to say the successful solution came courtesy of Sam Ballad and the THG. Nevertheless, a big thankyou to everyone on here who has offered advice and possibilities. I'm very grateful.

18th Mar 2017, 5:13 pm	#29
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 661	Re: GPO Jack unit 1B Can you post the successful solution here please - thanks

18th Mar 2017, 8:10 pm	#30
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B I decided to use a standalone handset and plug it into the 84a socket. There is a resistor T5 and T6. I think it's 3.3K. T6 and T7 strapped. T20 and T19 wire linked. T10, T11 and T12 strapped. T12 wire linked to T9. T13 and T14 strapped. T13 wire linked to T17. T16 and T17 strapped. Line cord red to T8, white to T18, blue to T6 and green to T15. T8 to T9 and T18 to T19 straps removed. Two hook switches will go here instead. Regulator 6B will fit between T11 and T17. Obviously no guarantee this configuration will work for everyone ! Attached Thumbnails

18th Mar 2017, 8:17 pm	#31
Pellseinydd Heptode Join Date: Jul 2007 Location: Flintshire, UK. Posts: 707	Re: GPO Jack unit 1B The circuit in message 15 works - it is the circuit of the Tele 787 modified to remove the coinbox elements. Bell only added if needed. I've just set it up as per the circuit in Msge 15 with a Tele 713 and a Jack Unit 1B - luckily I had some Tele 713s and Jack Units 1B in the 'Stores' . And it worked first time. Dialling tone loud and clear on lifting the handset. Replaced handset and dialled into the circuit the Tele 713/Jack Unit1B was fitted to and it rang out until I lifted the T713's handset and was able to speak between the two phones. Attached Thumbnails

18th Mar 2017, 8:22 pm	#32
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B Very good Pell. I must have got my wires crossed if mine failed back then. Still, the more the merrier.

19th Mar 2017, 5:45 am	#33
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B Pell, if yours is still built would you mind posting a photograph of the Jack unit so I can see the straps, wiring etc. Thankyou.

20th Mar 2017, 5:54 am	#35
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B Pell, there is a PM for you. Sparks

20th Mar 2017, 5:46 pm	#36
Pellseinydd Heptode Join Date: Jul 2007 Location: Flintshire, UK. Posts: 707	Re: GPO Jack unit 1B Hi Sparks Replied direct. I'm sure we'll crack it and let everyone know what the problem was.

8th Apr 2017, 11:03 am	#37
Sparks Heptode Join Date: Oct 2006 Location: Leeds, West Yorkshire, UK. Posts: 596	Re: GPO Jack unit 1B Eventually finished up with a functional 1B jack unit. It serves the red handset and yellow 713 in these pictures. The red lever key is the hookswitch. The black G handset on the left is on a different system altogether. The Sterdy door phone unit on the right isn't doing anything just yet and is purely decorative. Attached Thumbnails