Northern Electric 500AX not ringing!

[patcorr]

Hi guys,

I am new here and hoping to solve a problem that I has been haunting me for months now. I have 2 x 500 model NT telephones that I just cannot get to ring. They don't use the 425 network.

Printed on the underside is:
100D MK1002 TX6173
QSFE 500AX NT=84
MADE IN IRELAND

On the network board is the following:
QNB86E and underneath the network board is PO625892

If anyone can help me I woud be eternally grateful. And happy St Patricks Day from Ireland 

Thanks,
Pat
The schematics is inside the casing but I would need a microscope to see the writing! I can make and receive calls perfect but it just will not ring!
P.S. I added pictures in a reply below

[NorthernElectric]

I am not familiar with the network in your phone and am by no means an expert; sort of learning as I go.  So I will leave your technical questions for those with more expertise than I to answer.  But allow me to welcome you to the forum, and also to also wish you a Happy St. Paddy's day.  I picked up a 4 pack of Guinness Draft tallboys for tomorrow on my way home from work today, but I think I will have to see if I can get some more on my way home tomorrow because I think they will be gone by then.   

[patcorr]

Thanks for your reply  In hindsight I should have added pictures which I am going to do now! Definitely 4 of those tall ones is never enough, I hope they are draught cans and chilled nicely!

[compubit]

Now for a short break...

On a side note, to me, the dial just looks naked without the letters on a 500 set. Other models (especially the European ones) seem normal, but it's just weird to me.

I know some places in the US didn't use the metropolitan (with letters) dial, but on this style of phone...

Back to our original programming...

Nice looking phone. I'm surprised it has modular cords - it's the first European made I have seen with them.

Assuming the wiring would be similar to the U.S., there should be a capacitor in series with the ringer between the 2 incoming lines. If the capacitor is blown, then it's an open circuit and the dial won't ring.  If it's shorted, then the phone won't hang up.  Also, do other phones ring on the line? If so, are they all connected at once? You may not have enough ringing power for a mechanical bell.

Just a few thoughts.

Jim

[patcorr]

Hi Jim,

Thanks for your reply. I have noticed that too about the dial card. Most European ones that I have seen had them.

I have another older NT 500 with the 425 network already on the line that works perfect. I also connected the bells to the older set to check them and they rang perfect. Visually the capacitors look good.

The picture isn't clear as regards the wiring.
Line in:  Red -> L2, Green -> L1, but I have to bridge the wiring for the ringer some way and that is what gets me. Black ringer is connected to L2, but the red ringer is connected to what looks like TI2 from the yellow input (which is redundant) so where do I bridge the red ringer wire to seems to be the million dollar question?

I am learning about these sets as I go along,

Pat

[NorthernElectric]

The schematics is inside the casing but I would need a microscope to see the writing!

Here's a trick that I have used in the past to read things that I couldn't make out, even under magnification.  If you can take a good clear high resolution digital photo of the drawing, then you may be able to read it just fine on your computer display, by zooming and panning around.  To get a good sharp photo suitable for this, you may need to use a tripod, the macro setting (looks like a flower) on your camera, and experiment with lighting positions, as well as making sure your camera is set to the highest possible resolution.

[G-Man]

500AX Connections For Bridged Ringing...

Ringer Wire               Network Terminal
Black                =                      "L1"
Red                   =                      "L2"
Slate                 =                       "K'
Slate/Red         =                       "A"

[patcorr]

500AX Connections For Bridged Ringing...

Ringer Wire               Network Terminal
Black                =                      "L1"
Red                   =                      "L2"
Slate                 =                       "K'
Slate/Red         =                       "A"

I just had another look there now after a good nights sleep!
On this network there are no "K" or "A" terminals.
Slate = T3
Slate/Red = RX2

[G-Man]

The connections that were provided are for a Northern Telecom QSQM500AX; obviously a different beast than your 500AX.

[patcorr]

It must be the difference between the QSQM and the QSFE.

[patcorr]

I tried to get a good photo of the schematics inside the casing. Unfortunately this is the best I could get!

[G-Man]

Please check my annotations to your wiring diagram to verify that I have them correct.
If I am correctly following the wiring for the ringer, I suspect that this instrument is intended for use with a master socket, where the ringing capacitor resides.

If this is correct, then a small capacitor could be added between the yellow (Y) and Green (G) wires. I don't know the resistance of the ringer coil but here in the states it is generally a non-polarized, .47uf +/- capacitor.

[patcorr]

Thanks G-man,

I really appreciate your input and help. Your annotations are 100% and thinking about it you could be right. That is something I had forgotten about. Unfortunately our provider Eircom (previously P&T the now privatised state company that still hold ownership of the lines) updated all our sockets last year F.O.C when we updated our broadband. I'm not sure what the set up of these sockets is, I doubt it would be compatible with the older analogue system. We only have 2 wires entering the house which are still the original from when my house was built in 1965. These wires were then bridged before the master socket for the ringer wire. I still have one of the older master sockets that I know for sure holds a capacitor, in my box of tricks that I can wire up.
I find it strange that and older model that I have with the 425 network (1977, bridged) works fine but a later model is being a nuisance! I will try it tomorrow and let you know.
It is St Patricks Day and I have beer consumed and as much as I am itching to tackle it, I am not going to do it now!  

Regards,
Pat

[dsk]

Hi I found this page: http://homepage.eircom.net/~leslie/testpage/wiring.htm
The UK master had 1.8 microfarad capacitor, but as mentioned over 0.47 could be the right if the ringer are US style. Most European phones used 1 microfarad.

dsk

Edit:
http://blog.bogpeople.com/2007/12/the-eircom-master-socket.html
The Irish standard will look like US with ring tip and ground, but the ground contains 1.8 microfarad capacitor in series, and the ringing is between ground and ring.

[patcorr]

That is the exact socket I have and I have just checked. It does indeed have the capacitor. I will check my wiring throughout the house tomorrow. As Eircom rewired most of my sockets but not all. There is one master style socket still installed which was originally the only exension socket installed. I don't think it is bridged for the ringer from source. So am I right in saying that if I bridge the ringer wire from source onto the left hand connection of the Eircom master socket then it should go through the capacitor and the ringer should work on the 500AX if I have it connected to this socket?