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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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2nd May 2020, 12:15 pm | #1 |
Dekatron
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Plan 105 with external extensions
OK, so this one has had me scratching my head for few days without getting anywhere, but maybe someone here can throw some light on it.
As per the title, I am attempting to wire up an N625 planset with external extensions according to plan 105, but there are a few functions I can't get to operate correctly. - neither the main unit nor the extensions will ring on an incoming call*. The latter I would expect to ring when switched to "extn to exch". The former also on "spk to exch". - pressing the call button on an extension (while "on hook") fails to operate the buzzer in the main unit. Manually operating the armature of the relay in the ringing converter does operate the buzzer, but this relay doesn't operate when a call button is pressed. - when switched to "extn to exch", lifting the handset of an extension doesn't make a loop, and the buzz of the ringing current can be heard in the extension's receiver, until the handset of the main is lifted. The main handset can then be replaced and the extension remains "off hook" until the handset is replaced. I should say that pressing the appropriate call button on the main does ring the selected extension by activating the ringing converter. *I notice from the N diagram that the bells are shown connected between the B leg of the line and earth, so I find it unsurprising that a ringing current between the A and B legs is not activating them. What I can't see is how they should be operated. I have checked and rechecked my wiring, but cannot spot anthing amiss. I previously had this planset working with an internal extension without any problems but, especially having a converter, ringing 9A, wanted to try external extensions.
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2nd May 2020, 12:29 pm | #2 |
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Re: Plan 105 with external extensions
From what I remember these installations needed a signalling earth at the customer's end, one side of the ringing supply being earthed at the public exchange.
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2nd May 2020, 12:49 pm | #3 |
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Re: Plan 105 with external extensions
I rather suspected that might have been the case, so I'm onto a loser trying to operate in this mode from a standard line (i.e. an extension of my house PABX).
I don't believe this explains the other problems though. I will probably revert eventually to internal extensions with their multi-cored line cords.
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2nd May 2020, 2:18 pm | #4 | |
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Re: Plan 105 with external extensions
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2nd May 2020, 3:56 pm | #5 |
Dekatron
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Re: Plan 105 with external extensions
I tried connecting the signal earth to the A leg of the exchange line. This solved the lack of ringing on incoming calls but caused other problems - such as detecting the extension as off-hook even when it wasn't (if I recall correctly).
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2nd May 2020, 5:17 pm | #6 |
Triode
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Re: Plan 105 with external extensions
Hi Dave
I have managed to do this. I have set up a stand-alone system and it does involve joining the A wire to earth in the connection box 37. To save earthing the phones I used 3 wires to the extensions - though not in the traditional way. I can did out my my wiring diagrams if that will help? Regards, Wayne |
2nd May 2020, 8:32 pm | #7 |
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Re: Plan 105 with external extensions
Yes, I would indeed be grateful if you could dig out your modified wiring diagrams.
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2nd May 2020, 10:49 pm | #8 |
Triode
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Re: Plan 105 with external extensions
Hi Dave - here they are.
This will be slightly differnet to N626 as I have yet to obtain a genuine Converter, ringing No. 9A - so I built my own. The extensions are wired to LJUs rather than hard-wired. This makes it more flexible & means I can use standard line cords & extension cables. Also you will note in the second picture the extensions are slightly different. This is because I have not yet obtained the correct additional hookswitches, but you can work without them (as in extension 1). Hope this helps. Any questions - please ask. Regards, Wayne |
2nd May 2020, 11:08 pm | #9 |
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Re: Plan 105 with external extensions
Hi Dave - Just remembered something else which might help.
Ringing the main from the extension requires a line to be connected. This is because the button in the extension earths the B wire. The resultant line current then operates the relay in the ringing convertor. As originally wired this means line polarity is important. The PBX I was running this off was a BT 2+8 which when wired correctly switched the A+B polarity over when going from an exchange line to an intercom call. The way I got over this was running the extension "earth" wires back to BT7 in the planset junction box & linking it to the A wire in the planset (linking P6 to P7) Regards, Wayne |
3rd May 2020, 9:08 am | #10 | |||
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Re: Plan 105 with external extensions
Many thanks. I shall have a play with it this afternoon.
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Noted, but I had already discovered that things only really operated when connected to a line.
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3rd May 2020, 2:04 pm | #11 |
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Re: Plan 105 with external extensions
Am I missing something? Having worked through your wiring diagram, the only difference I can see (other than the modified power arrangements for your self-build ringing converter) is the insertion of a link between P6 (exch A leg) and P7 (earth), which (as I said in post no. 5) I have already tried.
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3rd May 2020, 2:33 pm | #12 |
Triode
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Re: Plan 105 with external extensions
Hi Dave.
I think that was the only change I made. Have you checked the voltage across the ringing convertor relay coil when pressing s button on an extension? I am wondering if the line current is not enough to energise the relay. Also do you still have the other issues you mentioned in your initial post? I did have some strange issues with mine to start with until I cleaned the piano buttons switch contacts & made sure they were correctly adjusted. Regards, Wayne |
3rd May 2020, 2:49 pm | #13 |
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Re: Plan 105 with external extensions
Yes, the only problem it has solved is the main not ringing on incoming call. The other problems remain.
I think I'll put it to one side for the time being and come back to it when I'm feeling fresher.
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3rd May 2020, 3:42 pm | #14 |
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Re: Plan 105 with external extensions
Hi, I'm sure I managed what you are trying to achieve with my Plan 105 "external" set up by adding a 1u8 capacitor between BT 6 and BT7, alternatively you could fit the cap in the Planset base between terminals 6 and 7 if there is room.
My set up is currently in the loft so when I (eventually) go up there I can check for you if you wish. With regard to your other issues, is your Planset a Mark 1 version with a transistor switch in the A leg as opposed to the later relay version? If so it may be that there is an issue with the transistor switch (just a guess). I seem to recall having similar issues with my set up once, I can't remember what caused it though....... Andrew |
3rd May 2020, 4:55 pm | #15 | ||
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Re: Plan 105 with external extensions
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Here is an image of the innards of the planset base and the label on the bottom cover:
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3rd May 2020, 5:09 pm | #16 |
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Re: Plan 105 with external extensions
That looks like a Mk2 Planset to me. It still has the PO 3000-style relay (the Mk3 has one of those little cradle relays), but the line current detector is a reed relay (the metal tubular thing at the bottom left of the photo) rather than the transistor circuit of the Mk1.
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3rd May 2020, 5:24 pm | #17 |
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Re: Plan 105 with external extensions
Thank you for confirming that the tubular item (which I didn't recognise) is the relay, thus identifying this as a Mk 2.
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4th May 2020, 11:06 am | #18 | |
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Re: Plan 105 with external extensions
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The effect is in fact no different from using a strap, but it feels more satisfactory to have DC blocked between the A leg and earth. The other three problems (extension not ringing on incoming call, extension not seizing the line until main goes off-hook, and extension not activating ringing converter's relay for buzzer in main) still remain unsolved.
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4th May 2020, 2:55 pm | #19 |
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Re: Plan 105 with external extensions
Tracing continuity, I found the lack of same from the relay (terminal 4 on RC) back to the B leg of the exchange, highlighting a break in the wire between the RC and the main terminal block - the wire had broken (within the insulation) next to BT14. Reconnecting it eliminated all three of the problems mentioned above.
When switched to "extn to exch", the buzzer in the main sounds as well as all bells? Is this what should be expected? If so, I think this unit is now fully functional. Many thanks to those who have advised, and I apologise that to some extent I have sent folks on a wild goose chase!
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4th May 2020, 3:09 pm | #20 | |
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Re: Plan 105 with external extensions
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Also is the Converter Ringing powered continusously, or only when the button is pressed? Because that could make battery power possible or not possible, which might be handy. |
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