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-   -   Key for 1970's payphone ? (https://www.vintage-radio.net/forum/showthread.php?t=158332)

vidapura 24th Jul 2019 12:17 pm

Key for 1970's payphone ?
 
Hi,
I'm working on a project for our computer museum here.
We got an old "Press button A" payphone .. I'm not sure of the correct designation for them.. heavy black metal thing with a button B for coin return. I remember them from when I was a kid in the 70's so am assuming its circa 1970.

Anyway, we built a phonebox for it and now I've nearly finished the project to connect it up to a Raspberry Pi. The idea is to have a "History Phone" where you dial a number like "1967" and the Pi will play back from interesting sound files from that year.. the number one pop song, new clips maybe.. etc etc.

So, we have all that working.. figured out all the switch debouncing and connecting to the GPIO of the PI... etc.

I'm at the stage of mounting the phone in the phonebox and thinking about where we might hide the Pi.

One idea is in the cashbox.. which we have access to.. the bottom 'door' slides out, no padlock on it.
But a better option would be in the actually body of the phone, the region where the B button is etc.. as there is already a hole in the back for a wire loom to exit.
Only problem is that this compartment is locked.. there is a keyhole in it and I've tried picking the lock etc.. (I can manage to get into desk drawers etc with a paperclip) .. but this thing is obviously designed to withstand the rigours of life on the street... so I can't manage it..

Just wondering if anyone knows where I'd get a key for the old phonebox or if there is a way of opening it without the key?
Just to stress , its not the cash compartment.. we have access to that.. its the body of the phone where the coins pass through on the way to the cashbox that we are interested in gaining access to.

Thanks

Pellseinydd 24th Jul 2019 7:35 pm

Re: Key for 1970's payphone ?
 
2 Attachment(s)
It will be a fairly standard key as the engineer would be issued with one to open all the A/B boxes in his area. The earlier A/B boxes were fitted with a two lever 'Lock No 31' which had a standard 'Key Lock J' whereas later A/B boxes had 'Locks No 39' which had a variety of keys. Attached is photo of a Key Lock J which is an original - marked 'HAS' the GPO manufacturers code for Hall Telephone Accessories Ltd who made the A/B boxes

These are British 'GPO' designations but many ex-GPO A/B boxes were sold to the Irish P&T in the 1960's so I'm sure the lock may be the same. Original Irish P&T ones will have 'P&T' stamped on the side of the box whereas ex-GPO ones will something like 'BCC No 8' the GPO designation of the outer case .

The keys are easy to get cut as they are a simple flat blade with a couple of 'nicks' in them - see photo. I bought an A/B box from New Zealand without keys and my local Master Locksmith 'picked the lock' and made a new key.

I have a 'renters' A/B box on its backboard which I have connected to an ATA working off CNet which can access recordings the World over. The ATA has inbuilt WiFi which works via my mobile phone so I can use the A/B box virtually anywhere. Other photo is of the A/B box and other phones set up at the ExCel Centre in London recently at a event for 'Openreach' the branch of British Telecoms which looks after the links between the exchange and the 'telephone'


Ian

emeritus 24th Jul 2019 10:32 pm

Re: Key for 1970's payphone ?
 
I have an ancient metal cupboard that uses this sort of flat key. I had no key for it, and could not get a drop-in replacement new lock, but my local locksmith was able to make me a set of keys for it for the cost of a replacement lock.

Graham G3ZVT 24th Jul 2019 11:47 pm

Re: Key for 1970's payphone ?
 
2 Attachment(s)
Quote:

Originally Posted by vidapura (Post 1162990)

So, we have all that working.. figured out all the switch debouncing and connecting to the GPIO of the PI... etc.

I'm at the stage of mounting the phone in the phonebox and thinking about where we might hide the Pi.

Thanks

Apart from hiding the Pi, I would have thought you need access to the interior in order to connect the dial to the GPIO pins.

Have you tested your project using another dial?
The dial in an A/B telephone has some "enhancements" compated to a regular rotary dial, I'm not sure how/if they will impact your project

This key originally opened an up & over garage door,

Attachment 187290

after a little filing it now opens this Post Office coin-box.

Attachment 187291

Pellseinydd 25th Jul 2019 9:29 am

Re: Key for 1970's payphone ?
 
The special 'coinbox' dial (Dial No 11, 13, 20, 23 or 24) is only needed if the coinbox is to function as originally set up. I suspect that the Museum's 'setup' (phone & A/B box on backboard) was already wired up on its backboard - hence getting working without needing access to the terminal strip in the locked A/B box.

The Irish P&T wired the A/B box up differently to the GPO - I have the original P&T diagram if necessary.

If setup as original i.e. a coin/s needed before it is possible to dial, will allow the caller to dial the recording but the A/B box will allow the caller to listen to the recording without having to press button 'A' and then press button 'B' to recover their 'call cost ;) - Coinboxes in the UK were not allowed to call recorded services, Speaking Clock etc. and I assume that was applicable in Ireland.
Ian

vidapura 25th Jul 2019 11:53 am

Re: Key for 1970's payphone ?
 
Hi everyone,

I'm really bowled over with the great responses to my question.
Thanks so much all of you. The detail is brilliant.

Thanks for taking an interest in the implementation details too.
Just to provide more info on those.. we just took the plastic front off the phone and connected directly to the microswitches in the dialler.
So, completely ignored the coin slot bit.
Its probably a bit of an ignorant approach but we just really boiled the phone down to a dialler with a few microswitches..

I just disconnected all the wires from the dialler to the circuit board and used the two wires (pink - common, orange - pulse) to get the number dialled, and another wire which gives me a pulse when the dial reaches home.
And did a little bit of desoldering to isolate the microswitch on the On Hook when the handset is lifted/put down.

A bit of debouncing was required then to make it possible to get the number right etc..

There are wires that run up the back of the wooden mounting board in a channel from the back of the phone ..they orginally disappeared into the back of the body but we commandeered them to connect the phone to the Pi.

And we have it working as-is right now..

I might try post a few pics if anyone's interested.

Anyway, thanks again .. its great to find a cadre of experts. !!

AND of course, all are welcome to visit if ye are ever in Galway. We're in the university.
(http://www.nuigalway.ie/visitorscomputermuseum/)

vidapura 25th Jul 2019 3:32 pm

Re: Key for 1970's payphone ?
 
5 Attachment(s)
Some pics attached of the payphone and some bits of the museum.
You can see the phonebox etc.

Oldcodger 25th Jul 2019 9:52 pm

Re: Key for 1970's payphone ?
 
Vidapura - I'm quoting from what I remember I was taught by my mentor on subs maintenance over 50 years ago. Inside the box was a lever set up, (UK boxes), which needed 4 x1D coins to move the arm. this arm ,moving removed the short from the dial and allowed persons to dial a number. At this time the transmitter was shorted out. On answer by the called person, the caller pressed button A and the short was removed from the transmitter. I never used coins( except when neat stacks were found on the box, indicating that IB were around, when the operator was called, asked to make out a ticket for date & time and asked to record the insertion of coins), but in other circumstances used my "J" key. .

vidapura 26th Jul 2019 10:30 am

Re: Key for 1970's payphone ?
 
Hiya,
Thanks for that.. yah I'm afraid I had limited time and just ploughed ahead and disconnected all the wires inside the phone from their respective connectors.. and just used a meter to ring out the wires and figured out which ones were for the dialling pulse and which was the 'dial-stopped' and 'on-hook'..
I should probably be classed as a vandal.. sigh... but at the time I could find no useful info about how to connect the phone to a RPi any other way...
Oh well.. you live , you learn...

Guest 26th Jul 2019 1:53 pm

Re: Key for 1970's payphone ?
 
Quote:

indicating that IB were around
IB?

Pellseinydd 26th Jul 2019 2:23 pm

Re: Key for 1970's payphone ?
 
The GPO's 'Investigation Branch' - the GPO 'police' ;)

Oldcodger 26th Jul 2019 9:48 pm

Re: Key for 1970's payphone ?
 
Well said ,that man. Merlin said "the GPO 'police' ". To pass on the flavour-blokes on call were given a free phone. Just that , one phone. To stop the whole house being disturbed at night , some blokes wired an extension to the bedroom. Verboten said the IB ,and there were tales of Pulse echo test gear being used on
employees free phone lines to stop this .

Pellseinydd 26th Jul 2019 10:05 pm

Re: Key for 1970's payphone ?
 
Going off topic a bit. I know someone who got a GPO 'engineer' to fit him a 'free' extension to the room upstairs where he had his amateur radio gear. That was where most of hos calls were made from. Then the ''GPO' turned up to investigate his setup. He was a party line and the so called 'engineer' had never worked on 'subs apparatus' and had wired the extension up so that when the 'Call Exchange' button was pressed it connected to the sharing partners metering. The 'engineer' had got the bell ringing correctly but not the correct metering when the exchange was called! GPO wrapped some knuckles if I remember correctly.

I had an extension provided 'for free officially' on my 'free exchange line' - needed in case I was called out - I was even provided with a van that was delivered to me at 5pm every day and collected again in the morning. Happy days before the GPO became the PO.


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