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-   -   GPO Jack unit 1B (https://www.vintage-radio.net/forum/showthread.php?t=134812)

Sparks 13th Mar 2017 1:28 pm

GPO Jack unit 1B
 
2 Attachment(s)
Hello. I'm trying to connect a 713 pendant telephone to a 1b jack unit. I have followed the instructions in diagrams N813 and N4699. I am getting a dialling tone at a good volume although the sidetone is a little quiet when I speak into the transmitter. Also, pressing and releasing the hook switch has no effect, i.e. the phone is constantly off hook.
I'm attaching a couple of pictures of the jack unit. I've temporarily taken out the 6B regulator to make the pictures clearer. Could anyone please spot where there might be something wrong ?

Thankyou

JohnBHanson 13th Mar 2017 8:20 pm

Re: GPO Jack unit 1B
 
You have shorted T19 and T20 which is where the hook switch would normally go.

Sparks 13th Mar 2017 8:56 pm

Re: GPO Jack unit 1B
 
Thankyou John. I removed the wire link which has restored the switch function. But when I press the switch I
can still hear a faint dialling tone and sidetone when I speak. I'll look again tomorrow but I would appreciate any more advice if you have any.

Ta.

AndiiT 13th Mar 2017 9:30 pm

Re: GPO Jack unit 1B
 
Hi, there is a circuit for Jack unit 1A (which is similar) on pages 5 and 7 here It appears that the terminals are not wired the same as a standard 746 telephone despite the circuit board looking identical. I seem to recall having some issues when trying to wire up my Jack unit 1B.

The diagram I have linked to relies on the key being thrown on the key and lamp unit to connect to the exchange line but it shouldn't be too difficult to work out where the hook switch from the pendant telephone needs to go in the circuit to create the line seizing loop.

Regards

Andrew

Sparks 14th Mar 2017 6:27 am

Re: GPO Jack unit 1B
 
Thankyou Andi. I'll look on Thursday when I'm next off work. I'm not brilliant with diagrams, mind, so I might need simple verbal instructions ultimately!

I should also add that this jack originally came fitted to a dial and key and lamp unit so it may not have been configured for a simple domestic BT line, which is what I want to use it for.

Sparks 15th Mar 2017 7:55 pm

Re: GPO Jack unit 1B
 
I've studied the diagrams of the 1A jack and I'm afraid I'm none the wiser, probably because I'm a tinkerer and not a trained technician ! To summarise my snags:

- The sidetone is on the quiet side, almost inaudible;

- I have now discovered that pressing the hook switch doesn't 'hang up' the phone at
all but just mutes the dialling tone or steady tone.

I have removed the wire link between T19 and T20.

Clearly I am out of my depth trying to figure out how to do this successfully. Any other instructions, suggestions etc gratefully accepted.

Thankyou.

Dave Moll 15th Mar 2017 8:28 pm

Re: GPO Jack unit 1B
 
I have to confess that I was none the wiser after studying the pages referenced above, either, as I couldn't marry what was there with the terminal numbers in your pictures.

What a shame they apparently went for a non-standard wiring scheme for this product, despite the terminal layout being so similar to that of a 700-series telephone. I would know exactly how to wire up the latter, but can't track down a diagram for the jack unit 1B.

Sparks 15th Mar 2017 9:32 pm

Re: GPO Jack unit 1B
 
Thanks Dave. Good to know I'm not alone !

Andi, do you happen to remember how you overcame your wiring problems ? I'm all for trial and error providing I don't cause any damage somewhere along the line.

How many switches are actually required to seize a line and switch on the speech circuit ? I've examined the innards of a regular 746 and the cradle switch of my 713 and they appear to match, i.e. a 2-pole on-off and a 3-pole changeover. Tell me if I've got this wrong.

Thankyou again for your help.

WayneL74 15th Mar 2017 11:04 pm

Re: GPO Jack unit 1B
 
Is this any help?

http://www.samhallas.co.uk/repositor...ocs/SA9228.pdf

Sparks 15th Mar 2017 11:16 pm

Re: GPO Jack unit 1B
 
1 Attachment(s)
I've managed to restore the unit to the state it was before I attempted to connect the 713 phone - thank goodness I kept notes of all the strap removals etc. I have also removed the 713 and tried the unit simply with a handset plugged in via a PO420/84A. It works fine with dialling tone and sidetone etc fully restored. So now it's really a question of which terminals to connect the hook switch to so I can turn the ****** on and off. I shall look in again tomorrow. Thanks again folks.

This is a picture of the restored unit, again with the 6B Regulator removed (and since refitted).

WayneL74 16th Mar 2017 12:55 am

Re: GPO Jack unit 1B
 
Having studied the diagram I posted, N846 (the one for the 746 telephone) & N813 (for the 713 telephone) I think I can see how you need to wire this.

I am assuming that tele 713 is wired as per N813 - http://www.samhallas.co.uk/repositor.../0000/N813.pdf

JK A Green goes to terminal 3 in the 713. White goes to T8 & blue goes to T9. Red goes to 7.

You will also need to wire the 2-pole switch in place of the link between 19 and 20. You need to connect terminal 4 in the 713 to terminal 19 in the jack, and terminal 5 in the 713 to terminal 20 in the jack.

That should allow the line hang up correctly.

Dave Moll 16th Mar 2017 8:33 am

Re: GPO Jack unit 1B
 
Like Wayne, I'm inclined to start from the wiring shown at the top of page two of the N813 diagram - assuming that the terminal assignments of the jack 1B match those of the bellsets shown, but I would suggest a few changes. With the exceptions below, I would include the straps shown.

As to the line cord, I would suggest the following:
"A" leg of line cord (white) to B18 (as shown)
"B" leg of line cord (red) to B8 (as shown)
"ringing wire" (blue) - if being used - to B6, and remove strap between B6 and B7,
otherwise park it on a spare terminal (say B15) and leave strap in place
green wire of line cord is unused, so park it on a spare terminal (say B14).

If a dial is not included, strap B9 to B10.

As to the switch between B19 and B20, this should be covered by the connections shown in the diagram, as the hook switch between T4 and T5 is shown connected between these two.

If you wish to reduce the ringing current drawn by this arrangement, replace the link between B4 and B5 with a 3K3 resistor. This is only an issue if you have other 'phones connected in parallel, so is a refinement to consider once the setup is working correctly.

Sparks 16th Mar 2017 10:51 am

Re: GPO Jack unit 1B
 
Thankyou Wayne and Dave. I shall resume this afternoon and advise accordingly. Fingers crossed.

By the way, I measured the voltage across the blue and white terminals on the 84A socket and it read 3.8v - I was expecting 3v. Is this within limits ?

Sparks 16th Mar 2017 2:33 pm

Re: GPO Jack unit 1B
 
I've admitted defeat on this one. I've tried everybody's suggestions and the hook switch on the 713 is not doing its job. Nothing wrong with the switch's function - I've tested it with a multimeter but it isn't cooperating with the jack unit.

Change of plan. I'm simply going to connect a handset to the jack using the 84A and PO420 and have a separate hook switch. I shall use a PO type 1000 lever key for this. Working out the right connections remains the tricky bit !

Pellseinydd 16th Mar 2017 6:43 pm

Re: GPO Jack unit 1B
 
1 Attachment(s)
See attached - Based on the circuit of a Tele 787 which uses the 'Telephone Unit D93093' which is the same unit that a 'Jack Unit 1B' uses. I've deleted the dial out of the circuit and added the terminals 'TU' for the PCB and 'T' for the terminals on the Tele 713. Also left the terminals that a bell would connect to. The Line Cord Red is connected to TU 9 and the White is connected to TU 15 which is also connected to T5. The blue and green should be connected to spare terminals TU16 and TU17. To use on line with other phones - remove the link between TU6 and TU7; connect Blue lead to TU6; remove strap between TU14 and TU15 and replace with 3.3K resistor. Hopefully that should work. Check you haven't left any straps in from original Jack Unit 1B setup. PM me if you can't read it and I can send a larger copy direct.

Sparks 16th Mar 2017 7:14 pm

Re: GPO Jack unit 1B
 
Thankyou Pell. I'll try this tomorrow.

Sparks 17th Mar 2017 11:57 am

Re: GPO Jack unit 1B
 
Pell, it's just occurred to me that I don't have any resistors knocking around. Is it essential for this job or can it be 'overlooked' ? Indulge my ignorance please - I'm no technician!

Dave Moll 17th Mar 2017 12:21 pm

Re: GPO Jack unit 1B
 
Just leave TU14 strapped to TU15 for the time being. The only potential problem of doing so is that other 'phones in parallel with this setup may not receive sufficient ringing current to ring properly. For the time being it will be fine.

Sparks 17th Mar 2017 1:47 pm

Re: GPO Jack unit 1B
 
Thankyou Dave. There will be no bell (or dial) on this phone. All but one of the ringers on the parallel phones are switched off.

Dave Moll 17th Mar 2017 3:41 pm

Re: GPO Jack unit 1B
 
Is there not a bell (or at least some form of ringer, such as a buzzer) between TU14 and TU5 - as implied by the diagram in post no. 15


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