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Old 8th May 2021, 5:37 pm   #1
Guy Bridge
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Default 746F Converted Dial phone Problems

Hi,

Any help you can offer please!

I have no technical knowledge of phones but thought I'd have ago at converting an old dial phone, to see if I could get it to work on a modern line. As far as I know, the phone did work prior to being disconnected from an old line, some time ago.

In my attempts to modify it I have connected a new cable fitted with BT431A connector, fitted a 3K3 resistor fitted and made internal connection changes, according to information I found on 'You Tube' - see attached photo for modified wiring layout.

On testing the phone it receives calls with no problem, but I cannot make calls from the phone.

Note - When listening to the dial tone with the receiver up I do not get the continuous dial tone I was expecting. The dial tone is broken (similar rhythm to an engaged tone but with the same type of sound of the normal dial tone)

Any ideas would be much appreciated.

Thank you,
Guy
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Old 8th May 2021, 5:54 pm   #2
Dave Moll
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Default Re: 746F Converted Dial phone Problems

Quote:
Originally Posted by Guy Bridge View Post
When listening to the dial tone with the receiver up I do not get the continuous dial tone I was expecting. The dial tone is broken (similar rhythm to an engaged tone but with the same type of sound of the normal dial tone)
Does this only occur with this 'phone? Normally, broken dial tone is sent to alert to, say, a message waiting if you have an answering service. I would expect, however, that this would be the same on any 'phone connected to the line; also that dialling out would not be affected.
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Old 9th May 2021, 7:45 am   #3
Guy Bridge
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Default Re: 746F Converted Dial phone Problems

Hi Dave,

Thanks for getting back to me.

You were right, I had 2 messages which must have arrived after I had disconnected my normal answerphone. The answerphone normally records any messages but was not connected at the time they arrived (BT Freelance XD8500).

When I re-connected the answerphone, I had the same 'broken' dial tone. After clearing the messages using the 1571 service, the dial tone returned to 'continuous'.

I reconnected the converted dial phone and can confirm that it now had the 'continuous' dial tone. However, when I tried to dial out unfortunately, it still doesn't work.

After each turn of the rotary dial I can still hear the 'continuous' dial tone. This carries on, even after I have finished dialling the number. It's as if the phone doesn't recognise me dialling out.

So a little bit wiser, but still unable to understand why dialling out is a problem!

Grateful for any more suggestions.

Thanks, Guy
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Old 9th May 2021, 10:54 am   #4
Nickthedentist
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Default Re: 746F Converted Dial phone Problems

Hello Guy,

This could be because your serivce provider doesn't support pulse (or "LD" = Loop Disconnect) dialling. After all, it was pretty much obsolete (for everyone except collectors) at least 20 years ago.

Try this: Lift the handset so that you get a dial tone, then rapidly press and release one of the two black plungers (the ones that the handset depresses when you hang up). This effectively dials a "1", so the dial tone should stop. If it doesn't, it almost certainly means that your line is designed exclusively for DTMF dialling.

There are workarounds which can be considered if required though.
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Old 9th May 2021, 12:03 pm   #5
Dave Moll
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Default Re: 746F Converted Dial phone Problems

Probably the simplest and cheapest of the workarounds is a tone dialler that you place against the mouthpiece of the telephone. It has a keypad on the back with which you tap out the number to dial and it plays the MF dialling tones into the microphone. These seem to be available on eBay starting at under £15. Other suppliers are available.

If you wish something a little more transparent that enables you to use the telephone's own dial, you need something like a Dialgizmo connected between your telephone and the line.
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Old 9th May 2021, 5:53 pm   #6
Oldcodger
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Default Re: 746F Converted Dial phone Problems

Some lines do not support LD (dial working), and will only work with DTMF. The simplest to tell whether it's your phone or system is to pick up the handset and see if "tapping" the cradle (quickly tap the hook springs under the handset) and see if you can break dial tone. Proved by loss of dial tone, followed shortly by Number Unobtainable Tone.
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Old 10th May 2021, 7:43 am   #7
Guy Bridge
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Default Re: 746F Converted Dial phone Problems

Hi again,

Thanks for all your suggestions. I've tapped the black cradle quickly and sure enough, the continuous dial tone stops. After a short while a get a message saying 'sorry there is a fault'. If I try dialling, the continuous dial tone returns. So receiving calls OK but still seems odd that I'm unable to dial out.

I know that phone previously worked properly in my neighbours house, when it was connected to the line via the old GPO junction box. I don't know who the service provider was but I'm with Talk Talk, no idea whether this makes any difference.

Can anyone confirm that the connections on my phone, are correct, from the photo on my original post?
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Old 11th May 2021, 12:05 am   #8
hamid_1
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Default Re: 746F Converted Dial phone Problems

I'm afraid your TalkTalk phone line is the most likely cause of this problem. I've had the same experience.

Your wiring looks OK. If you can take your phone to a friend or neighbour with a BT line (or another provider that re-sells BT, such as Plusnet) and test it there, this should prove whether or not the phone is working.

When you dial a number on a rotary phone, a switch inside the dial mechanism opens and closes rapidly as the dial turns backwards. The switch opens and closes once when you dial 1, twice when you diaL 2 and so on. This is called loop-disconnect or pulse dialling. When you dial zero, it opens and closes ten times. There should be ten pulses per second. Sky, TalkTalk and Virgin Media have different equipment to BT. Their lines are often a lot more fussy about the exact timing of the dial pulses. If your vintage phone's dial is running at slightly the wrong speed, the line may reject the digit you dialled and go back to the dial tone. BT phone lines seem to be more tolerant of old slightly erratic dial phones.

Other than changing providers, there are several solutions to this problem.

You can try to adjust the speed of the dial, so that it's precisely 10 pulses per second, but dial speed adjustment can be a bit tricky for a beginner.

There are various converters available, such as Rotatone, Dialgizmo, Ligo Bluewave and X-link which will convert rotary dial pulses into tones, just like the sounds you hear when you press the keys on a modern push-button phone. The pulse to tone converters are designed to work with old mechanical dial phones, even those which are no longer very accurate.

The hand-held pocket tone dialer has already been mentioned. You simply hold this over the mouthpiece of the vintage phone and press the keys on the tone dialler's keypad to dial the required numbers.

Another solution, if you have a modern cordless phone connected to the same line as your vintage one: dial the wanted number on your cordless phone while standing next to your vintage phone. Pick up the vintage phone, then end the call on the cordless phone. You can continue the conversation on the vintage dial phone and hang up when finished.
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Old 11th May 2021, 7:55 pm   #9
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Default Re: 746F Converted Dial phone Problems

It may be some wrong connections of the dial or whatever the cord marked is from.

A led with suitable series resistor and a 9V battery in series with the phone should let the led light up when going off hook, and flash (on/off) when you let the dial return from 0.

dsk

Source of the other picture: https://www.britishtelephones.com/tr....htm#converted
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Old 12th May 2021, 7:45 am   #10
Guy Bridge
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Default Re: 746F Converted Dial phone Problems

Thanks so much for your explanations and suggestions, I really appreciate your help.

I have a cordless phone connected to the line so will experiment to see if I make a call and continue it when I switch over to the vintage phone.

The whole exercise of converting the vintage phone is just for a bit of fun but I'm enjoying the challenge and learning a lot from you guys, in the process.

I'll let you know how things pan out.

Thanks again,
Guy
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