Vintage 706L not ringing
 

I’ve managed to convert my 706L phone and it has dialling tone and can make and receive calls but it doesn’t ring.
I have removed the 3.3k resister and replaced it with a wired connection in case that was blocking it.
The coils are 2 x 500.
I can flick the connections by hand to make a little ding but the clanger doesn’t move.
It is plugged into a wall socket where my 300 Bakelite works and rings but when I replace it with the 706, no luck.
( As you will note I have limited grasp of he jargon). Hope someone can make a suggestion to help me.

Re: Vintage 706L not ringing
 

Hello Daisy May, and welcome to the forum.

There is no need for a 3k3 resistor - a solid connection will do. Do your connections look like the one in the attached diagram, including the continuity of the line conductors from terminals to plug? It has been known for plug terminals 3 and 4 to be the wrong way around.

If so, does the hammer and armature to which the hammer is attached pivot freely across the ends of the bell-bobbins?

If yes and yes, do you have a multimeter from which you can check the d.c. resistance between terminals T4 and T16, working inwards to your bell-bobbins?

If all the above is OK, and you're reading about 1000 Ohms on your multimeter at T4 and T16, is the wiring on your bobbins connected correctly and not been nobbled with? The inner wire of one bobbin should be connected to the outer wire of the other one. In other words, they should be linked left-left or right-right, not left-right or right-left.

Hope this gets you started. :)

Re: Vintage 706L not ringing
 

The likelihood is that your 706 is plugged into a socket that doesn't supply ringing current to pin 3 (pin 4, usually blue wire, of the plug). I assume, therefore, that your 300 series 'phone is wired to use its internal capacitor, whereas the 706 has the ringer connected to the third wire.

I am a little unclear what is happening when you say you "flick the connections by hand". Which connections are you flicking? If they are not mechanically connected to the ringer, it implies that a connection is being momentarily made and sending an impulse to the ringer - which at least further implies that the ringer itself is OK, though you may have a bad connection that you're flicking.

Re: Vintage 706L not ringing
 

thanks for replying.
the part I can flick is the plate at the end of the coils that I presume should spring into action to make the bells ring. I've also done the multimeter test and the gongs seem to sound.
so should I remove the blue wire from T3 and put it in T4? Also what about the resister, should I return it to T4-T5?
here's hoping.....

Re: Vintage 706L not ringing
 

Russell W B, thanks

well, as I'm still a bit new to this I'll have a go a describing.....
T1 red and T2 green and T3 blue all go to handset lead
T1 and T2 are connected by red resister(?)

Then T4 pale pink goes under the coil and is linked to T5 which is linked to T6.
T6 blue and T8 red go to other lead -phone wire.

T10 white goes to handset lead.
T15 green to phone lead.
T16 pale pink to other coil and brown to PRESS button.
T16 linked to T17 that has blue and grey both going too PRESS button.
T18 white to phone lead.

Phew!

Re: Vintage 706L not ringing
 

The red component is a pair of diodes rather than a resistor. Its purpose is to prevent high-voltage spikes (acoustic shock) from reaching the receiver of the handset)

The "pale pink" wire is presumably to one side of the bell coil, connected via T5 and T6 (optionally via 3.3K resistor) to the ringing wire in the line cord. For the ringer to work in this configuration, this needs to be fed with ringing current via the capacitor in the master socket, so if you are using an extension socket connected via a two-wire connection, there will be no ringing current and the bells will therefore not ring.

If you don't have more than one loop-disconnect (pulse) dialling telephone connected at any one time, and therefore bell-tinkle during dialling is not a problem, you can ignore (and disconnect) the blue wire and connect T6 to T7 to use the internal capacitor for ringing. Make sure also that T8 is connected to T9.

I assume that T18 is linked to T19 otherwise the 'phone would be completely disconnected from the line. The connections you describe for T16 and T17 imply that the PRESS button is not in use and is shorted out. You either need to connect T17 to T18 or move the brown of PRESS to T18 (if the PRESS is a latching switch that then acts as bell on/off). I would be inclined to go for the first option in the first instance.

Re: Vintage 706L not ringing
 

Is the "hammer" which strikes the gongs free to move between the two gongs?

Re: Vintage 706L not ringing
 

Phew indeed! Can you set your multimeter to a.c. Volts and see if you're getting around 75V when measuring across T5/6 (linked) and T16/17/18/19 (linked): white and blue incoming wires from your telephone lead and plug when you make your telephone ring? You'll need the telephone to be 'on-hook', ie: handset sat on cradle.

I trust T16, 17, 18 and 19 are all linked?

Re: Vintage 706L not ringing
 

Can you post a pic of how the board's wired?

Re: Vintage 706L not ringing
 

Do you have other phones plugged into the line ? If yes then it could be that the REN value has been exceeded by the low impedance bells on the 706, especially if the 300 Bakelite is plugged in also.

Rog

Re: Vintage 706L not ringing
 

Daisy May...have a look at post #10 in this old thread. Its about a 300 type phone but your 700 type is the same principle and in my days as a lineman was a very common cause.

https://www.vintage-radio.net/forum/...ad.php?t=41547

Post #11 shows a useful picture.

Re: Vintage 706L not ringing
 

Nickthedentist - I have been trying to post a picture but I'm being told the file isn't valid.

David - I've tried a bit if dusting it all seems to move quite freely.

Dave Moll - I tried your list but still no luck.
Not sure if I should put it back to where I started, or not!

Thanks to everyone who's tried to help me - I'm close to giving up on it now I'm afraid - it seems to be beyond my reach.

Re: Vintage 706L not ringing
 

See here:-

https://www.vintage-radio.net/forum/...ad.php?t=77650

Re: Vintage 706L not ringing
 

Attaching photo of wiring

Re: Vintage 706L not ringing
 

It looks like you've wired it to use the internal ringing capacitor (part of the round metal can in the top right corner of your photo) rather than one in the master socket. You don't get anti-tinkle that way, but my feeling is that it's a lot more likely to work without problems.

The wiring looks right for that.

It's possible there's a fault in some part of the telephone. Do you have a multimeter and basically know how to use it?

Re: Vintage 706L not ringing
 

May I suggest that you connect the blue wire to T14 (which is spare) just to keep it anchored to avoid shorting anything out.

Are you saying that it still doesn't ring wired as shown?

Re: Vintage 706L not ringing
 

I see it's a 706 Mk:II with the printed circuit board. It would be worth lifting the board out and checking beneath for broken PCB tracks or a corroded solder joint in the vicinity of the bell capacitor part of the circuit.

When your telephone is meant to ring, do you hear anything in the receiver when it is 'on-hook'?

Re: Vintage 706L not ringing
 

You might find Sam Hallas' website helpful here.

Re: Vintage 706L not ringing
 

It doesn't ring as shown. But when I 'answer' it I can speak and hear as I should.

Yes, I'll fix the blue wire to T14.

Re: Vintage 706L not ringing
 

no sound of anything when I ring the number and listen in handset with hooks down, not even a click.

I have an old multimeter (ie not digital ) and can use it under instruction. Ive already tested ohms to show that ringer is good. What next?