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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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30th Nov 2009, 8:30 pm | #1 |
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GPO 706 in trouble.
I have a 706 that has not been converted to the little six contact plug. It has 5 wires going to an old GPO wall box.
No matter how I connect the wires to the new style wall box I get no proper results - just a high speed clicking sound. So far I have worked the following out (although I know there are sites full of this info, my 'problem' may be recognised by readers here). T18 = White = Position 2 on new plug T 8 = Red = Position 5 on new plug T 6 = Blue = Position 4 on new plug T15 = Green = Position 3 on new plug (or T17 as it was on the 706) Is the phone broken - or does this look wrong to you? SEAN
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There are only 10 types of people, those who understand the binary system, and those who don't. Last edited by Darren-UK; 2nd Dec 2009 at 3:29 pm. Reason: Title change. There's no such thing as a 'BT 706'. |
30th Nov 2009, 8:34 pm | #2 |
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Re: BT 706 in Trouble
Hi Sean,
Could you post a good pic of the board as you've got it wired, please? Nick. |
30th Nov 2009, 8:46 pm | #3 |
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Re: BT 706 in Trouble
Photo as requested:
SEAN
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There are only 10 types of people, those who understand the binary system, and those who don't. |
30th Nov 2009, 10:05 pm | #4 |
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Re: BT 706 in Trouble
OK, Sean, this doesn't seem to have been "converted" yet.
Start by removing the straps linking T6-T7 and T8-T9, and instead fit them between T5-T6 and T17-T18. Your pic's not 100% clear; could you tell us the order of the coloured wires in the line cord, please? Then get back to us |
1st Dec 2009, 9:57 am | #6 |
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Re: GPO 706 in trouble.
No, I think you are right in that it has not had these mods made - I will do this tonight. BUT, there is no mention of the orange wire....... Polite suggestions please as to where to stick it!
SEAN
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There are only 10 types of people, those who understand the binary system, and those who don't. |
1st Dec 2009, 11:57 am | #7 |
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Re: GPO 706 in trouble.
The answer, Sean, is to "park" it on one of the unused terminals, i.e. T11 to T14.
The green wire is similarly redundant, and is conventionally connected to T15. Nick. |
2nd Dec 2009, 8:40 am | #8 |
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Re: GPO 706 in trouble.
Well, it now has been converted - still does not work!!! I can hear the (unfiltered) ADSL on the line, but no dial tone. When I dial I get silence, then a beep, but it does not dial out of the house.
Next steps? SEAN
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There are only 10 types of people, those who understand the binary system, and those who don't. Last edited by SeanStevens; 2nd Dec 2009 at 8:41 am. Reason: spelling error |
2nd Dec 2009, 9:35 am | #9 |
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Re: GPO 706 in trouble.
Disconnect your telephone from its lead and plug. Connect an audio output from a wireless or other music source (or an audio oscillator output at about neg. 10db WRT 1mW at 600 Ohms) to terms: 8 and 18 in your telephone.
Can you hear the audio through your receiver? Does the audio cut off when you replace the handset? Do this then report back.
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2nd Dec 2009, 2:28 pm | #10 |
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Re: GPO 706 in trouble.
Couple other things, assuming your telephone passes the 'music' test, as I described earlier:
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2nd Dec 2009, 4:31 pm | #11 |
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Re: GPO 706 in trouble.
No, there are no extra switches or buttons on this 706.
I'll try these tests asap tonight, although I know the phone does not have the resistory thingy between terminals 4 and 5. More later, thanks for the help. SEAN
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2nd Dec 2009, 4:49 pm | #12 | |
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Re: GPO 706 in trouble.
Quote:
Another test you can do is to connect a battery (4.5 - 12V will do) across terms. 8 and 18 and blow into the microphone. Can you hear yourself in the receiver? Does it crackle? The reason I suggested shorting out the mic in the earlier test is that the resistance of the carbon mic varies with position and DC bias current, and you won't get a steady reading, hence the separate test above.
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2nd Dec 2009, 6:17 pm | #13 | |
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Re: GPO 706 in trouble.
Quote:
I don't know what this proves, but it seems to have passed. SEAN
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There are only 10 types of people, those who understand the binary system, and those who don't. Last edited by Darren-UK; 2nd Dec 2009 at 6:44 pm. Reason: Quote realised. |
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2nd Dec 2009, 6:55 pm | #14 |
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Re: GPO 706 in trouble.
It proves that you can receive speech; that your ASTIC isn't bust. You'll need to run through the more, er, 'scientific' tests with an ohm-meter, as I later described.
Before you do that, though, connect a battery to 8 and 18 and see if your mic is working.
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2nd Dec 2009, 7:19 pm | #15 |
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Re: GPO 706 in trouble.
With a battery on 8 and 18 I got nothing from the speaker to earpiece.... I changed the mouthpiece for a known good spare....... Still nothing.
This doesn't look good - the detective work is slow with me doing the tests! SEAN
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2nd Dec 2009, 7:21 pm | #16 |
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Re: GPO 706 in trouble.
I have no strap between terminals 8 and 9 - but neither does this:
http://www.britishtelephones.com/tranchan.htm#converted I'll try one SEAN
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2nd Dec 2009, 7:33 pm | #17 | |
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Re: GPO 706 in trouble.
Quote:
Is your regulator OK? - The little card that slides into the slot beneath the cradle-switch? Reverse it (up-end it) and see if you get any side-tone with the battery test. Still with the battery test, and with T8 to T10 connected directly together (strapping out the dial-contacts), see if you can hear yourself. If you can, it's your dial pulse contacts that are O/C.
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2nd Dec 2009, 9:02 pm | #18 |
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Re: GPO 706 in trouble.
I didn't realise that was removeable!!!
Changed it top to bottom - battery test is bad with it in either orientation..... Frustrating this!!! SEAN
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2nd Dec 2009, 10:21 pm | #19 |
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Re: GPO 706 in trouble.
Have you tried doing the battery test with T8 and T10 shorted together yet?
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3rd Dec 2009, 9:25 am | #20 |
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Re: GPO 706 in trouble.
...And don't forget to check the continuity of your mic wires from telephone to handset as well!
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