Wiring for 706 Telephone. - UK Vintage Radio Repair and Restoration Discussion Forum

knocklyon35 · 24th Nov 2010, 2:03 pm

Hi,

I am new to this forum but previously have lots of experience rewiring old phones. Maybe I've lost my touch

but I seem to have lost my way with the 706 I have. Currently, by disconnecting blue wire from T6, the phone now rings but when handset picked up - can hear the rining tone - i.e. it has not really been picked up/connected.

Also there is another blue wire from the phone which when connected to T8 means phone seems "engaged". When pressing hand cradle down, for a split second there is a dial tone but then goes dead.

Any help appreciated. Ive included photo. Im confused by original wiring as Ive repositioned straps according to diagrams on this forum.

Many, many thanks!!!

knocklyon35 · 24th Nov 2010, 4:43 pm

Sorted! Followed instructions in another post: turned small pcb board around & seems to have solved prob!

Thanks for this forum!

AndiiT · 24th Nov 2010, 5:08 pm

Hi,
From what I can see of your photo your additional Blue wire needs to be connected to T16 as it appears to be one of the Bell motor wires, connecting this to T8 will almost certainly engage your line!

On the subject of your original fault it sounds like the white wire of the line cord may have become open circuit, this would certainly give the symptoms that you describe.
Other alternatives are a badly seated or faulty regulator, that's the little circuit board sat between the switch hooks if you weren't already aware of this, or a high resistance hook switch or associated component somewhere between T19 and the transmission circuitry.

The first thing I would try is a replacement line cord, ensuring that the telephone is strapped/wired as follows.

HANDSET
RED - T1
GREEN - T2
BLUE - T3
WHITE - T10

LINE CORD
RED T8
BLUE T6
GREEN T15 (Spare)
WHITE T18

STRAPS
T4 - T5 - T6
T16 - T17 - T18 - T19

Ensure that the leads from the bell motor are connected one to T4 and the other to T16, it doesn't matter which way round, you may find that one lead is longer than the other to allow it to reach T16.

Once you have done this if the fault is still apparent you may have to do some fault finding using a multimeter.

Regards
Andrew

Station X · 24th Nov 2010, 5:12 pm

Quote:

turned small pcb board around & seems to have solved prob!

It's not possible to insert the regulator board the wrong way round, the slot in the regulator PCB prevents you from doing this. The picture in the first post shows the regulator in the active position.

What you have now done is to reverse the regulator which renders it inactive. Unless the regulator is faulty I cannot see how having the regulator active could give the symtoms you decribe. Try reinserting it in the active position and see what happens.

AndiiT · 24th Nov 2010, 5:14 pm

Hi,
A second look at your photograph and the associated N diagram for a 706, suggests that extra Blue lead that you have in your telephone may not be from the Bell motor but is part of the dial pulse muting circuitry and should be connected to T3 (see note f in the enclosed diagram)

Andrew

russell_w_b · 24th Nov 2010, 5:16 pm

Are your white / red wires connected to pins 2 and 5 respectively in your plug? Or, if so, are your socket wires the right way around compared to other sockets on your line?

Check out your plug wires with the lead towards you, the clip to the right, and the copper pins uppermost, noting that pins 1 and 6 aren't normally connected (they'll have no copper pins fitted) and that the wire going to T8 on your telephone goes to pin 5 on your plug and the wire going to joined-up Ts 16-17-18-19 goes to pin 2 on your plug. Check that your blue wire - the one you should connect to joined-up Ts 6-5-4 - goes to pin 4 on your plug.

Your links look OK, although I note you haven't fitted a REN resistor yet - you mightn't need one, so just get the phone to work first!

24th Nov 2010, 2:03 pm	#1
knocklyon35 Retired Dormant Member Join Date: Nov 2010 Location: Kent. Posts: 20	Wiring for 706 Telephone. Hi, I am new to this forum but previously have lots of experience rewiring old phones. Maybe I've lost my touch but I seem to have lost my way with the 706 I have. Currently, by disconnecting blue wire from T6, the phone now rings but when handset picked up - can hear the rining tone - i.e. it has not really been picked up/connected. Also there is another blue wire from the phone which when connected to T8 means phone seems "engaged". When pressing hand cradle down, for a split second there is a dial tone but then goes dead. Any help appreciated. Ive included photo. Im confused by original wiring as Ive repositioned straps according to diagrams on this forum. Many, many thanks!!! Attached Thumbnails

24th Nov 2010, 4:43 pm	#2
knocklyon35 Retired Dormant Member Join Date: Nov 2010 Location: Kent. Posts: 20	Re: Wiring for 706 Telephone. Sorted! Followed instructions in another post: turned small pcb board around & seems to have solved prob! Thanks for this forum! Attached Thumbnails

24th Nov 2010, 5:08 pm	#3
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Wiring for 706 Telephone. Hi, From what I can see of your photo your additional Blue wire needs to be connected to T16 as it appears to be one of the Bell motor wires, connecting this to T8 will almost certainly engage your line! On the subject of your original fault it sounds like the white wire of the line cord may have become open circuit, this would certainly give the symptoms that you describe. Other alternatives are a badly seated or faulty regulator, that's the little circuit board sat between the switch hooks if you weren't already aware of this, or a high resistance hook switch or associated component somewhere between T19 and the transmission circuitry. The first thing I would try is a replacement line cord, ensuring that the telephone is strapped/wired as follows. HANDSET RED - T1 GREEN - T2 BLUE - T3 WHITE - T10 LINE CORD RED T8 BLUE T6 GREEN T15 (Spare) WHITE T18 STRAPS T4 - T5 - T6 T16 - T17 - T18 - T19 Ensure that the leads from the bell motor are connected one to T4 and the other to T16, it doesn't matter which way round, you may find that one lead is longer than the other to allow it to reach T16. Once you have done this if the fault is still apparent you may have to do some fault finding using a multimeter. Regards Andrew

24th Nov 2010, 5:14 pm	#5
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Wiring for 706 Telephone. Hi, A second look at your photograph and the associated N diagram for a 706, suggests that extra Blue lead that you have in your telephone may not be from the Bell motor but is part of the dial pulse muting circuitry and should be connected to T3 (see note f in the enclosed diagram) Andrew

24th Nov 2010, 5:16 pm	#6
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	Re: Wiring for 706 Telephone. Are your white / red wires connected to pins 2 and 5 respectively in your plug? Or, if so, are your socket wires the right way around compared to other sockets on your line? Check out your plug wires with the lead towards you, the clip to the right, and the copper pins uppermost, noting that pins 1 and 6 aren't normally connected (they'll have no copper pins fitted) and that the wire going to T8 on your telephone goes to pin 5 on your plug and the wire going to joined-up Ts 16-17-18-19 goes to pin 2 on your plug. Check that your blue wire - the one you should connect to joined-up Ts 6-5-4 - goes to pin 4 on your plug. Your links look OK, although I note you haven't fitted a REN resistor yet - you mightn't need one, so just get the phone to work first! __________________ Regds, Russell W. B. G4YLI.