Another GPO 746 not ringing.

[Rob_harris]

Hi,
Please can you help, I'm currently converting GPO 746 and are having problems with the bell ringing. I have followed the conversion steps

1. Remove strap T6 - T7.
2. Remove strap T4 - T5.
3. Insert strap T5 - T6.
4. Red wire of line cord to T8.
5. Blue wire of line cord to T6.
6. Insert straps T16 - T17 - T18 - T19.
7. White wire of line cord to T18.
8. Green wire of line cord to T15.
9. Insert a 3.3K resistor between T4 - T5 (added 3.3 resistor).
10.Insert a Rectifier No. 205 (if needed) between T1 and T2. (already in place)

The phone works fine, I get dial tone and make and receive calls, except the bell doesn't work when plugged in the BT socket.
It rings when I krone down the wires directly to the socket Pin's 2,5, 3.
Anybody got any ideas on what the problem maybe

Many Thanks

[russell_w_b]

Originally Posted by Rob_harris

It rings when I krone down the wires directly to the socket Pin's 2,5, 3.
Anybody got any ideas on what the problem may be?

Where are you Kroning from? Are you patching from socket pins 2, 3, 5 direct to the terminal block on your telephone? Does this include the lead fitted to your telephone or not?

[Rob_harris]

Hi Russell,

This is the lead directly from the phone to the BT extension socket.
I did the conversion and with the original lead (Red, White, Blue & Green)
I thought before I crimped the 4 pin BT plug onto the lead, I'll test the phone as I didn't know if it worked. After I punched it down, the bell worked.
I then crimped the BT plug on and tested the lead (multi meter) which was fine.
Then I plugged it in and made an incoming call, but the bell didn't work

[russell_w_b]

Originally Posted by Rob_harris

'I then crimped the BT plug on and tested the lead (multi meter) which was fine.
Then I plugged it in and made an incoming call, but the bell didn't work...'

Can you test your phone 'n' lead in another socket? Conversely, can you test another telephone - one that requres a third 'ringing' wire - in that socket?

Is pin 4 of the plug (that mates with pin 3 of the socket) sitting low?

Are pins 2 and 5 of the plug (that mate with pins 5 and 2 of the socket) sitting proud?

You have connected the blue wire to pin 4 of the plug and not pin 3, haven't you? The plug wires (1)2345(6) left-to-right, looking with the pins on the top pointing away from you and the lead towards you mate to opposite socket connections, confusingly...

[AndiiT]

Hi,
I would echo what russel has already said/suggested here. It sounds like you have what is sometimes referred to as a "Line reversal" where the ringing current is being applied across the capacitor and not the Bell motor, this can only be caused by incorrect wiring.

Before removing/refitting another plug to the line cord a quick check would be to swap the red and white leads, on T8 and T18 respectively, in the phone - if you now have ringing on an incoming call this would prove that the plug is incorrectly wired.

If all else fails go down the "two wire" route by removing the Blue lead from T5 and strapping T8 - T9 and T6 - T7 as long as their is an internal capacitor in the telephone this will ensure the phone always rings, the trade off is that you may get bell tinkle when dialing out on other phones connected to the line.

Regards

Andrew

[Dave Moll]

If the plug is fully reversed (i.e. correct sequence but starting at the wrong end), you would presumably also need to swap green and blue.

[Rob_harris]

Another 746 back in service.

I checked the BT plug and confirmed that the blue wire was going to pin 4 and that is was sitting proud.
Andrew said about ‘line reversal ‘swapping the Red wire on T8 with the White wire on T18 I swapped them over made incoming call – hey presto it started to ring.

Thanks for all your advice