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Old 4th Dec 2017, 11:02 pm   #1
deckstar
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Default GPO Telephone 746. New member.

Hi all.

Just bought a GPO 746 for my wife’s Christmas present and finished converting it to work. However I may have a small fault but not sure, when I lift the handset the bell chimes (tings) and the same when the handset is replaced. Is this normal?

Any help would be great!!

Thank you.
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Old 5th Dec 2017, 9:15 am   #2
russell_w_b
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Default Re: GPO Telephone 746. New member.

Hello Deckstar, and welcome to the forum.

You will sometimes get a transient pulse through the bell (and capacitor in the NTE) when lifting and replacing the handset; it's quite normal and depends on where the armature rests after it stops ringing. Does it tinkle when dialling? Have you disconnected the telephone's internal capacitor by breaking links either side of terminals T9 and T10? When it does ring, is it a healthy, consistent ring?

I get the same, occasionally, and sometimes you can hear the armature pulling over but not striking the bell. The polarised bells are very sensitive indeed (some more than others) and I have known me answer the telephone with an initial 'ting' as the exchange relay goes over giving rise to a transient d.c. pulse before ringing current is applied.

Some US telephones (and very, very early UK ones) had a biassed armature where a small spring would pull the bell to the same rest position after ringing, but the 59A bell in your telephone can land anywhere, and, as such, is at the behest of whether a positive or negative-going transient pulse is applied with relation to the polarity of the bobbin magnets.
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Old 5th Dec 2017, 9:30 am   #3
Nickthedentist
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Default Re: GPO Telephone 746. New member.

Hello and welcome.

To summarise Russell's comprehensive reply, YES, that's normal, one of the nice quirks of old phones like this.

Nick.
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Old 5th Dec 2017, 12:00 pm   #4
Dave Moll
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Default Re: GPO Telephone 746. New member.

You also probably need to be aware that exchange equipment sometimes reverses the polarity on the line for testing purposes, and this may conceivably also result in a ting. I have never experienced this with a 746 myself, but I did have a Trimphone that emitted a short "beep" when this occurred. As I had this as my bedside 'phone initally, it soon got swapped with one elsewhere in the house.
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Old 5th Dec 2017, 3:16 pm   #5
ThePillenwerfer
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Default Re: GPO Telephone 746. New member.

I wish mine WOULD do that as it seemed to be usual in the old days but not now.

I could never make a call upstairs without my parents knowing as the 746 in the hall would give a 'ting' when the one upstairs was lifted. That said the wiring at that time was 'un-official' shall we say.
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Old 6th Dec 2017, 1:54 am   #6
rambo1152
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Default Re: GPO Telephone 746. New member.

I am pretty certain my local exchange (System Y) still gives a polarity reversal before ringing. Perhaps it's only lines where CLID enabled.
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