BT 746 Tinging from bell when dialing

[Ken]

I have a BT 746 which I adapted for plug and socket operation. Although this worked well at my fathers house (BT line) it never rang well at my house (Virgin line) even when no other phone was connected. On reading around I found that the Virgin bell voltage was reported to be lower than the BT voltage. I had the chance to buy a 4000 ohm bell cheaply and on fitting this the bell rang well with no other problems. The other phones connected were a BT Raport answer phone and a modern electronic phone. The only bell enabled is that on the 746. The BT Raport developed a fault and I swapped it for a BT Response 20 answer machine. This is when the tinging problem started. I am sure I have read of a solution for this but I cannot find the source. Can anyone suggest a solution to this problem?

Regards,

Ken.

[Dave Moll]

I assume that you do have the bell connected between blue and white, rather than using the internal ringing capacitor.

[Ken]

Hi Dave

I don't have the phone apart at the moment but I will check this and report back.

Regards,

Ken.

[Ken]

Hi Dave

The wiring is slightly complicated due to the fact that the phone has a bell on/off switch which in turn has three wires (blue, grey and brown) connected to it two of which seem to be tied together. The wiring is as follows.
T17, T18 and T19 are linked. The white and the blue and grey from the switch are connected on this link. The brown from the switch and one end of the bell are connected together on T16. T4 and T5 are linked. The other end of the bell and the blue wire are connected on this link. It looks to me as if the bell is connected to the blue and white wire via the switch. Hope this description helps.

Regards,

Ken.

[AndiiT]

Hi,
I am not sure about Virgins ringing voltage (and current) being different to BT's, I know that the idle line voltage is slightly less but this should not cause any ringing problems.

It sounds as if the Bell on/off switch is wired correctly but before you get too involved with the wiring of the switch check that the telephone is wired and strapped as follows-

RED of line cord to T8
WHITE of line cord to T18
BLUE of line cord to T6
GREEN of line cord to T15 (spare)

Ensure that there a NO straps between T6 - T7 and T8 - T9

Strap T4 - T5 - T6
Strap T16 - T17 - T18 - T19, leaving the wires from the bell on/off switch connected as previously mentioned.

If the phone does not now tinkle, remove the strap between T6 - T17 to enable the bell switch.

I have read a little about the BT response 20 answering machine from here and it looks like this may be intended for two - wire devices, which could give rise to a bell tinkle fault if both telephone and Answering machine are connected via a socket doubler.
Have you tried the telephone without the answering machine connected?
If disconnecting the answering machine solves the tinkling problem you may have to wire in a separate socket, with no bell wire (terminal 3) fitted to connect the answering machine to.

Regards
Andrew

[Ken]

Hi Andrew

The red, white, blue and green wires are wired as you outlined. T17, T18 and T19 are strapped. T16 is strapped to these when the switch is in the on position. The switch is working so this looks OK. However, although T4 and T5 are strapped together T6 was not strapped to them. I have just tried a temporary strap and tinging has now gone. I had disconnected the other phones and answer machine. I have reconnected them one at a time and still no tinging. I have phoned out and got my daughter to phone me back and all is OK. I am about to make a more permanent link between T6 and T4 and T5. Is it possible to buy the metal links anywhere? Can I just thank you and Dave for your help.

Regards,

Ken.

[Dave Moll]

There's nothing special about the links - a piece of wire will perform exactly the same function. If, however, you're after the aesthetic look, PM me your address and I'll pop one or two in the post.

[Ken]

Hi Dave

I have put in a wire link and the phone is working fine. You are right about the metal link. I would like one mainly because it would look better although it would also lie flatter. Can I therefore take up your offer of a link. I will PM you with my details.

Thanks again,

Ken.

[Ken]

Hi All

The link Dave sent me arrived today and is now inside my phone. Thanks again to Dave and Andrew for their help. I've attached a picture of the phone complete with it's new link.

Regards,

Ken.