GPO Bellset 26 on Canadian/US network

[Fennec]

Hello:

I am a new member, and my recent acquisition of a British GPO 232 phone and a 26 bellset is the reason I have joined this forum.

The intent is to make a functional "King Pyramid" GPO phone that we can use.

First order of business was to try and test functionality of the Bellset on its own (not connected to the phone). And right of the bet a problem - no ringing.

The bellset is wired to a standard BT diagram N526. I have checked all wire paths for continuity - everything checks, no shorts, no open connections as per diagram. Capacitor is OK at 2 uF. No detectable capacitor leakage. The only off thing - one coil tests at ~1,240 Ohm, and the other is ~500 Ohm, as per drawing. I have connected the BT (new) cord to it as described in the http://www.britishtelephones.com/bellst26.htm , including installation of 3.3 kOhm resistor between terminals 9 and 8.

I have removed the gongs, connected the bellset through a BT to RJ11 adapter, called the number - no motion of the striking hammer...
My Automatic Electric Model 40 rang very happily though...

So, since I lack the experience and knowledge, I would like to ask for an advice - where should I start troubleshooting? What should I check?

Any pointers would be greatly appreciated.

[TelePlay]

Can you post a picture of the ringer? It might be something other than a straight line ringer. That would be a good start for others to help you.

Also, a picture of any diagrams found in the bell set, or phone, would be of help.

[Fennec]

Can you post a picture of the ringer? It might be something other than a straight line ringer. That would be a good start for others to help you.

Also, a picture of any diagrams found in the bell set, or phone, would be of help.

The diagram I have attached to this post is the only diagram that I have, and it fully corresponds to the "guts" of the bellset... The only thing I have done is added the colored lines to indicate the connections to the BT line cord, and highlighted the odd value of one of the ringer coils...

[Fennec]

Sorry, forgot the pictures - this is the bellset as received, before I have added the "bridges" between terminals. According to the link I have posted, this bellset is suitable for use as a straight ringer, as well as connected through the telephone.

[TelePlay]

Yes, that looks like a straight line ringer.

Did you try disconnecting the ringer wires from the terminal and hook them up to the ringer terminals (with that ringer disconnected) on your AE 40 to see if the ringer works. Or do you have a way to test the ringer, a ring generator device? That would narrow it down to a bad ringer or a good ringer and something else.

I'm sure other members with more knowledge of these will reply over the next few days helping you with the problem.

[unbeldi]

Hmm, if the diagram you posted is drawn according to your actual wiring, I would not expect the ringer to work properly.

The diagram shows the ringer in series with a 3.3 kΩ resistor directly across the line without use of the capacitor.
A proper ringing bridge should include the capacitor in series as well.

So, perhaps it works better if you connect the white line wire to terminal 4 or 5 on the strip, instead of being on 2.

[unbeldi]

What is the typical ringing frequency in installations where this bell box was originally used?

The ringing capacitor is pretty large at 2 µF, perhaps ok for a 1000 ohm ringer, but as you report yours is actually 1740 Ω.
With a capacitor this large, I would probably not use that resistor, but try it out first. Try shorting it with a banana clip.

[Jack Ryan]

Hmm, if the diagram you posted is drawn according to your actual wiring, I would not expect the ringer to work properly.

The diagram shows the ringer in series with a 3.3 kΩ resistor directly across the line without use of the capacitor.
A proper ringing bridge should include the capacitor in series as well.

So, perhaps it works better if you connect the white line wire to terminal 4 or 5 on the strip, instead of being on 2.

In the UK they use a central capacitor, not one per ringing device. Three wires run from the central point to each telephone - L1, L2 and the Bell wire. Only thing is the Bell wire forms part of the audio circuit.

As you know, the resistor is a half hearted attempt to create a high impedance ringer.

Jack

[Jack Ryan]

One of the bell coils has an abnormally high resistance - both should be 500 ohms

Jack

[Jack Ryan]

The subject says "on Canadian/US network".

That means forget the wiring advice on Bob Freshwater's site and revert to original wiring (N332 & N526).

Original ring frequency was 16 2/3 Hz but the capacitor was also part of the audio circuit.

Jack

[Ktownphoneco]

Attached is a modified version of the schematic you posted.    Try connecting your central office line as indicated.    It shows the line connection change suggested by Unbeldi, and eliminates the resistor Jack referred to as the "half hearted" attempt to convert the ringer to a high impedance version.      If you haven't already checked, it might be a good idea to remove the 2 machine screws holding the circuit board in place, and carefully lift and twist it slightly, in order to verify that the empty terminals and jumpers shown on the schematic, are in fact, arranged as indicated. 
Even if it doesn't vibrate itself off the table, at least you'll know the ringer itself is functioning to some degree.

Jeff Lamb

 

[Jack Ryan]

Just for reference, here are links to the N diagrams I referred to earlier.

The phone itself: http://www.samhallas.co.uk/repository/n_diagrams/0000/N332.pdf

The Bellset itself: http://www.samhallas.co.uk/repository/n_diagrams/0000/N526.pdf

Connecting together: http://www.samhallas.co.uk/repository/n_diagrams/4000/N4300.pdf

Jack

[Fennec]

Attached is a modified version of the schematic you posted.    Try connecting your central office line as indicated.    It shows the line connection change suggested by Unbeldi, and eliminates the resistor Jack referred to as the "half hearted" attempt to convert the ringer to a high impedance version.      If you haven't already checked, it might be a good idea to remove the 2 machine screws holding the circuit board in place, and carefully lift and twist it slightly, in order to verify that the empty terminals and jumpers shown on the schematic, are in fact, arranged as indicated. 
Even if it doesn't vibrate itself off the table, at least you'll know the ringer itself is functioning to some degree.

Jeff Lamb

Thank you - I will try to connect the terminals as you have indicated. I did lift the terminal strip - everything checks out, no mystery connections. Would you recommend shunting the second coil - to bring the resistance in line with nominal value prior to testing?

[Fennec]

Just for reference, here are links to the N diagrams I referred to earlier.

The phone itself: http://www.samhallas.co.uk/repository/n_diagrams/0000/N332.pdf

The Bellset itself: http://www.samhallas.co.uk/repository/n_diagrams/0000/N526.pdf

Connecting together: http://www.samhallas.co.uk/repository/n_diagrams/4000/N4300.pdf

Jack

Thank you, Jack - greatly appreciated. If all else fails, I'll try to connect the bellset through the phone - just in case it is indeed not suitable for use as ring extender on Canadian 2-wire network...

[Jack Ryan]

Thank you, Jack - greatly appreciated. If all else fails, I'll try to connect the bellset through the phone - just in case it is indeed not suitable for use as ring extender on Canadian 2-wire network...

You're welcome.

There is nothing special about Canadian telephone lines. A Bellset No 26 (or other) British bellset is happy to ring in Canada - even if the cadence is not right ;-)

I'm not happy about a winding of 1200 ohms. Can you re-check that making sure you have a good connection (but be careful not to break the winding wire)?

Jack