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Old 17th Mar 2017, 3:59 pm   #21
Sparks
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Default 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 !
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Old 17th Mar 2017, 4:24 pm   #22
TonyDuell
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Default 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.
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Old 17th Mar 2017, 9:38 pm   #23
Pellseinydd
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Default 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.
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Old 18th Mar 2017, 7:32 am   #24
Dave Moll
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Default 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.
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Old 18th Mar 2017, 8:28 am   #25
JohnBHanson
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Default 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
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Old 18th Mar 2017, 8:29 am   #26
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Default 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).
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Old 18th Mar 2017, 11:16 am   #27
Sparks
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Default 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.
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Old 18th Mar 2017, 4:09 pm   #28
Sparks
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Default 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.
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Old 18th Mar 2017, 4:13 pm   #29
JohnBHanson
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Default Re: GPO Jack unit 1B

Can you post the successful solution here please - thanks
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Old 18th Mar 2017, 7:10 pm   #30
Sparks
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Default 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 !
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Old 18th Mar 2017, 7:17 pm   #31
Pellseinydd
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Default 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.
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Old 18th Mar 2017, 7:22 pm   #32
Sparks
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Default 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.
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Old 19th Mar 2017, 4:45 am   #33
Sparks
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Default 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.
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Old 19th Mar 2017, 4:07 pm   #34
Pellseinydd
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Default Re: GPO Jack unit 1B

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

regards
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Old 20th Mar 2017, 4:54 am   #35
Sparks
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Default Re: GPO Jack unit 1B

Pell, there is a PM for you.

Sparks
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Old 20th Mar 2017, 4:46 pm   #36
Pellseinydd
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Default Re: GPO Jack unit 1B

Hi Sparks

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