Can anyone help identify this phone please? - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

andy1702 · 13th Aug 2015, 8:36 pm

Hi Nick,

Photos are already at the beginning of the thread. All I've done is added a temporary line cord in the normal way. Things basically seem to work, it's just the volume (or rather lack of it).

Andy.

Nickthedentist · 13th Aug 2015, 8:40 pm

Thanks Andy.

I saw those, but I wanted to cast an eye over your "conversion", though you do sound like an expert in that respect.

I think it should work OK with a normal line. I suspect it's hard wired as if the plug-in regulator sub-PCB found in 706s is inserted backwards, i.e. shorted out.

The PCB-built 706-type phones were quite prone to broken tracks on the board. It might be worth whipping the board out and doing some continuity checks.

I've also had the ASTIC (transformer) fail with abused phones. Again, check the resistance of its windings with the ones printed on it.

Nick.

andy1702 · 13th Aug 2015, 8:56 pm

I'm no expert Nick.

You prompted me to go back and double check everything. I found my wiring was ok, but I'd missed the fact there was a link missing between T17 and T18. I've now fitted a link from the bits box and it's both making and receiving calls loud and clear. The clicks are still loud when dialling, but I think I know how to quiet them down a bit. I did think the ear piece was supposed to short out when the dial is off normal though.

TonyDuell · 14th Aug 2015, 5:44 am

The earpiece is shorted out on dialing, that's the function of the blue and slate (grey) wires connected between T1 and T2 and 2 of the dial terminals. At the dial end, the contacts between those wires close when off-normal.

Most of the time the problem is dirty contacts in the dial. I have found the best way to clean them is to take a narrow strip of thin card, soak it in propan-2-ol (isopropyl alcohol, whatever...) slide it between the contacts, turn the dial off-normal and pull it out. Don't use anything (more) abrasive. Do it a few times and the contacts should be OK again.

andy1702 · 14th Aug 2015, 7:51 am

Thanks Tony, I'll give that a try. I've already had to adjust the contacts because the weren't opening and closing as they should. They at least go together now but I did notice they looked black, so it probably is a layer of grime.

Nickthedentist · 14th Aug 2015, 8:03 am

They do tend to look black anyway though.

Do what Tony says. You could use Servisol Super 10 switch cleaner too, sprayed onto the card (not the dial).

Turn the dial until the contact pair you want to clean are open, insert the card, then rotate and hold the dial until the contacts are closed, and work the card back and forth a few times. Repeat with a fresh section of card until the amount of grime coming of becomes minimal. Repeat for the other two contact pairs.

Glad you found the missing link BTW... I had a suspicion it might be something very simple.

N.

julie_m · 14th Aug 2015, 2:38 pm

Quote:

Originally Posted by andy1702

I've done the 'normal' plug conversion on this phone now, but there's a problem. When I lift the handset the dial tone is so faint in the speaker I can hardly hear it. It will dial other phones ok and I can ring in to it, but the speaker is so faint I can't hear anything from the calling phone. Also the calling phone doesn't seem to be able to hear anything coming from this phone's mic. The only thing on this phone that can be heard clearly (too clearly actually) are VERY loud clicks when the dial is returning.

That sounds like a possible problem with the dial-off-normal contacts.

EDIT: Looks like you already fixed that problem; but the other issues mentioned since point towards dial-off-normal contacts, too.

midshires · 28th Sep 2015, 5:05 pm

The S series number on the base and stamped into the capacitor indicates it was made by AEI (previously Siemens Brothers). The Southern Region of British Railways used 706 telephones with 'L' dials on its PABX extensions, normally with black cases as these were cheaper than two-tone grey ones. I would imagine this telephone was used on some organisation's system, possibly even at AEI's factory at Woolwich. It would not have been for export (unless to the Channel Islands), as no other country used the British letters. AEI did make a variant of the 706 called the 806 for export to Canada; this had Operator against the digit zero and MNO against digit 6. It also had a 2,000-ohm ringer. Andy Emmerson.

13th Aug 2015, 8:36 pm	#41
andy1702 Retired Dormant Member Join Date: Jun 2015 Location: Chesterfield, Derbyshire, UK. Posts: 110	Re: Can anyone help identify this phone please? Hi Nick, Photos are already at the beginning of the thread. All I've done is added a temporary line cord in the normal way. Things basically seem to work, it's just the volume (or rather lack of it). Andy.

13th Aug 2015, 8:40 pm	#42
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,841	Re: Can anyone help identify this phone please? Thanks Andy. I saw those, but I wanted to cast an eye over your "conversion", though you do sound like an expert in that respect. I think it should work OK with a normal line. I suspect it's hard wired as if the plug-in regulator sub-PCB found in 706s is inserted backwards, i.e. shorted out. The PCB-built 706-type phones were quite prone to broken tracks on the board. It might be worth whipping the board out and doing some continuity checks. I've also had the ASTIC (transformer) fail with abused phones. Again, check the resistance of its windings with the ones printed on it. Nick.

13th Aug 2015, 8:56 pm	#43
andy1702 Retired Dormant Member Join Date: Jun 2015 Location: Chesterfield, Derbyshire, UK. Posts: 110	Re: Can anyone help identify this phone please? I'm no expert Nick. You prompted me to go back and double check everything. I found my wiring was ok, but I'd missed the fact there was a link missing between T17 and T18. I've now fitted a link from the bits box and it's both making and receiving calls loud and clear. The clicks are still loud when dialling, but I think I know how to quiet them down a bit. I did think the ear piece was supposed to short out when the dial is off normal though.

14th Aug 2015, 5:44 am	#44
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Can anyone help identify this phone please? The earpiece is shorted out on dialing, that's the function of the blue and slate (grey) wires connected between T1 and T2 and 2 of the dial terminals. At the dial end, the contacts between those wires close when off-normal. Most of the time the problem is dirty contacts in the dial. I have found the best way to clean them is to take a narrow strip of thin card, soak it in propan-2-ol (isopropyl alcohol, whatever...) slide it between the contacts, turn the dial off-normal and pull it out. Don't use anything (more) abrasive. Do it a few times and the contacts should be OK again.

14th Aug 2015, 7:51 am	#45
andy1702 Retired Dormant Member Join Date: Jun 2015 Location: Chesterfield, Derbyshire, UK. Posts: 110	Re: Can anyone help identify this phone please? Thanks Tony, I'll give that a try. I've already had to adjust the contacts because the weren't opening and closing as they should. They at least go together now but I did notice they looked black, so it probably is a layer of grime.

14th Aug 2015, 8:03 am	#46
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,841	Re: Can anyone help identify this phone please? They do tend to look black anyway though. Do what Tony says. You could use Servisol Super 10 switch cleaner too, sprayed onto the card (not the dial). Turn the dial until the contact pair you want to clean are open, insert the card, then rotate and hold the dial until the contacts are closed, and work the card back and forth a few times. Repeat with a fresh section of card until the amount of grime coming of becomes minimal. Repeat for the other two contact pairs. Glad you found the missing link BTW... I had a suspicion it might be something very simple. N.

28th Sep 2015, 5:05 pm	#48
midshires Triode Join Date: May 2007 Location: Northampton, UK. Posts: 36	Re: Can anyone help identify this phone please? The S series number on the base and stamped into the capacitor indicates it was made by AEI (previously Siemens Brothers). The Southern Region of British Railways used 706 telephones with 'L' dials on its PABX extensions, normally with black cases as these were cheaper than two-tone grey ones. I would imagine this telephone was used on some organisation's system, possibly even at AEI's factory at Woolwich. It would not have been for export (unless to the Channel Islands), as no other country used the British letters. AEI did make a variant of the 706 called the 806 for export to Canada; this had Operator against the digit zero and MNO against digit 6. It also had a 2,000-ohm ringer. Andy Emmerson.