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-   -   Problem with telephone 248 and bellset 44. (https://www.vintage-radio.net/forum/showthread.php?t=177044)

john777 25th Feb 2021 1:46 pm

Problem with telephone 248 and bellset 44.
 
Hello
I have recently acquired the above model bakelite phone.
I have re-wired as per instructions on the britishtelephones.com website, as below. I get a dial tone and I can ring into the phone and speak, but I cannot dial out on it. If I attempt to dial out all that happens is that it immediately goes back onto the dialtone. Experience tells me this is a wiring problem but I have never come across this model before so could someone kindly give me some pointers as to why this is happening
I have double checked the wiring several times and am pretty sure it is correct


"T3 to B19 and B20 - black of connecting cord.
T9 to B23 and B24 - pink of connecting cord.
T10 to B17 - brown of connecting cord.
T11 to B16 - grey of connecting cord.
T1 to B15 - blue of connecting cord.
Remove link B13 to B14.
Move the orange of connecting cord from B18 to B14 - the other end is connected to T2.
Blue of the line cord to B14.
White of the line cord to B1.
Red of the line cord to B3 and B4.
Insulate green of the line cord as it is not used."

russell_w_b 25th Feb 2021 2:16 pm

Re: Problem with telephone 248 and bellset 44.
 
Does your exchange support loop-disconnect dialling? Do other dial telephones work on the line you are using?

Dave Moll 25th Feb 2021 4:34 pm

Re: Problem with telephone 248 and bellset 44.
 
If the answer to Russell's question is no, then you will need something to convert LD pulses to MF tones, such as a Dialgizmo. (Other pulse-to-tone converters are available.)

john777 25th Feb 2021 5:08 pm

Re: Problem with telephone 248 and bellset 44.
 
Hello
Thanks for reply
I have several other bakelite dial phones, which all work on the same line

russell_w_b 25th Feb 2021 5:49 pm

Re: Problem with telephone 248 and bellset 44.
 
1 Attachment(s)
Would this drawing of a 232 help? I haven't had anything to do with a Bellset 44 but it sounds like your problem isn't at that end of things. Yu could buzz out the pulse contacts and check they open and close accordingly as you dial. It's possible to test the make / break ratio if the fault is nothing more obvious, and this is described in recent posts.

Dave Moll 25th Feb 2021 8:55 pm

Re: Problem with telephone 248 and bellset 44.
 
Now that we've eliminated non-acceptance of LD dialling, I'll compare your wiring described above with how my bellset 44 is wired. Hopefully, I'll report back tomorrow - unless someone comes up with something sooner.

john777 25th Feb 2021 10:32 pm

Re: Problem with telephone 248 and bellset 44.
 
I have swapped the dial with one from a working phone and the problem remains. Again based on my limited experience this feels like a wiring problem so a comparison with a working model would probably be extremely useful

dagskarlsen 26th Feb 2021 6:14 am

Re: Problem with telephone 248 and bellset 44.
 
If you disconnect the blue wire on the diagram above, does it call out? (#2 in the phone)

john777 26th Feb 2021 2:32 pm

Re: Problem with telephone 248 and bellset 44.
 
Hello
Sorry I don't know what that diagram is supposed to represent.
When you say disconnect the blue, there is a blue line from the phone jack attached to B14 and a blue line of the connecting cord which runs from T1 to B19,B20 and B21. This is in accordance with the instructions above.
Is it one of these that you want me to try and disconnect?

Dave Moll 26th Feb 2021 2:48 pm

Re: Problem with telephone 248 and bellset 44.
 
Rather than dismantling my bellset 44, I started by looking at diagram N4308 according to which I wired my bellset 44 (with two "internal" extensions). Unfortunately, I can't see how the wiring you describe relates to this. On what is the wiring you describe based?

Also, I assume you have this wired simply as a stand-alone telephone without any extensions attached, nor for that matter a bell for receipt of incoming ringing.

dagskarlsen 26th Feb 2021 5:56 pm

Re: Problem with telephone 248 and bellset 44.
 
I am far from sure, but try the blue on B14, and see whats happening.
dsk

john777 26th Feb 2021 6:16 pm

Re: Problem with telephone 248 and bellset 44.
 
Hello
Thanks for replying
As stated I have used the instructions in the Britishtelephones.com website.
I have no idea what he would have based that on.
I am trying to set it up as single standalone phone with no extensions or bells.

Dave Moll 26th Feb 2021 6:49 pm

Re: Problem with telephone 248 and bellset 44.
 
Could you possibly point me to the page in Bob's site containing the instructions please?

edit: Forget that - I've found it.

Dave Moll 26th Feb 2021 7:10 pm

Re: Problem with telephone 248 and bellset 44.
 
I think I see the problem. The instructions you describe are for connecting a bellset 39A.

If you have a bellset 44 you need the instructions in the next section on that page.

john777 26th Feb 2021 10:44 pm

Re: Problem with telephone 248 and bellset 44.
 
Unfortunately not that easy. I just posted the wrong instructions
These were the ones I used, I have double checked

GPO Telephone 248 and Bellset No.44

Telephone and Bellset are wired to follows (no bells are fitted):-

T3 to B34 and B35 - black of connecting cord.
T9 to B31 - pink of connecting cord.
T10 to B26 - brown of connecting cord.
T11 to B25 - grey of connecting cord.
T1 to B19, B20 and B21 - blue of connecting cord.
Remove any links between B13 and B14.
Remove any links between B17 and B18.
Move the orange of connecting cord to from B27 to B14 - the other end is connected to T2.
Blue of the line cord to B14.
White of the line cord to B1 and B2.
Red of the line cord to B3 and B4.
Green of the line cord - insulate - not used.

Dave Moll 27th Feb 2021 10:05 am

Re: Problem with telephone 248 and bellset 44.
 
The only oddity I can spot there is that T9 should connect to B31 and B32, as B31 is connected internally to nothing other than B32, though this connection only serves to enable the dial to be shorted out in the "extn to exch" position.

The move of T2 (orange) from B27 to B14 bypasses the internal 2μF capacitor in order to use the external one connected by the blue wire from the master socket.

Just to double-check, you are using this setup with the selector switch set to "spk to exch" I presume.

john777 1st Mar 2021 1:27 pm

Re: Problem with telephone 248 and bellset 44.
 
Hello
Thanks for replying, I have tried strapping B31 and B32. Unfortunately there is no change, I can get a dial tone and phone in but cannot dial out

Dave Moll 1st Mar 2021 2:24 pm

Re: Problem with telephone 248 and bellset 44.
 
If B31 and B32 weren't previously strapped, then the dial probably should have worked even if "extn to exch" were selected rather than "speak to exch".

If you have a (preferably analogue) multimeter, try connecting it (set to ohms) between T3 and T9. With the dial at rest it should read at or near zero ohms. After dialling 0, while the dial is returning, the pointer of an analogue meter should flutter or a digital meter should give a variable or non-zero reading. If the readings remain at zero ohms, it probably means that something is shorting out the dial contacts.

Would it be possible to post images of the wiring? An independent check can sometimes spot something that one has missed.

john777 1st Mar 2021 6:44 pm

Re: Problem with telephone 248 and bellset 44.
 
2 Attachment(s)
Hello
I have done the test with the multimeter, with the phone plugged in and the multimeter at lowest setting for ohms, it reads 0.6
If I then dial 0 after the dial returns it shows multiple readings and then returns to 0.6, which I think means it is not shorting out.
I attach a couple of photos of the wiring in the base, very difficult to get the top bit as so many wires going in there.
Just wondering about the green and white wires connecting wires between base and terminal. As they are not mentioned in the instructions I have assumed they are not required and insulated them.
Also is it not possible to connect the phone jack directly into the phone unit, bypassing the bellset which as it doesn't actually ring doesn't actually serve any useful purpose

Dave Moll 1st Mar 2021 7:32 pm

Re: Problem with telephone 248 and bellset 44.
 
Assuming that the connecting cord is correctly wired at the telephone end (which, as you say, is difficult to photograph), I can't see anything that would cause the problem described. The only anomaly I can see between your wiring and N4308 is that there is no strap between B17 and B18, meaning that the blue line cord and orange connecting cord are isolated from the main unit.

You could repeat the exercise with the multimeter, but using T1 instead of T9. If that works, try B34 and B21, and finally B1/2 and B3/4. If the dial pulses are making their way all the way through to the last two (i.e. the incloming line) then something very strange is happening.

I am assuming that the green and white connecting wires go to T10 and T11 (N4308 doesn't give me colours, so I would need to open my bellset to check), in which case you can safely ignore them as they are only significant on "speak to extn, exch held".

Concerning your final point, you could indeed wire directly to the 248 without using the bellset 44. It is effectively a 232 without an internal capacitor and with an additional springset in the hookswitch (connected between T10 and T11), though the termainals are differently numbered. In this case:
T1 to white of line cord
T2 to blue
T3 to red
and leave all other terminals unconnected.


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