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Early 500s x 3!

Started by andy1702, July 14, 2017, 08:03:00 AM

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andy1702

Being in the UK I don't often find American phones. I just picked up a particularly interesting batch yesterday though as part of a bigger purchase.

Here we have three early Western Electric 500s. Two dated 1952 and one dated 1964. All of these have metal finger wheels. One is complete, while the other two are just missing the card holder.

None of these have come with line cords, so if anyone can tell me how to fit UK cords to these for use on the madern UK system (with the capacitor in the wall socket) I'd be very grateful.

Andy.
Call me on C*net 0246 81 290 from the UK
or (+44) 246 81 290 from the rest of the world.

For telephone videos search Andys Shed on Youtube.

andy1702

More detailed shots of the first phone.
Call me on C*net 0246 81 290 from the UK
or (+44) 246 81 290 from the rest of the world.

For telephone videos search Andys Shed on Youtube.

HarrySmith

Nice score! Congratulations!
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

Ktownphoneco

Andy   ...   Great find, especially since the sets are so far from home.   I have no experience with "in wall" capacitors, however I can't see why it wouldn't be a straight forward process to bridge the ringer connections.     Since you found the sets in the U/K, you might want to check and see if someone hasn't already made the changes.
Check the 4 ringer conductors, and connect them as follows  : (1) Red to "L-2" on the network.  (2) Black to "L-1" on the network.    (3)  Slate (Gray) to "K" on the network.  (4) Slate-Red to "K" on the network.   
Slate and Slate/Red conductors would, in a North American system, connect to "K" and "A" in order to access and use the ring capacitor inside the sealed network.     But since your telephone system already has a ring capacitor installed ahead of the line cord, the above connections will basically remove the capacitor inside the network, and utilize the ring capacitor inside your wall jack.
If my mind isn't functioning yet this morning, and my methodology is incorrect, I'm sure someone else here on the forum will jump in and correct me.
The on-board capacitor in the 500 set should be around .45 mfd.     What's the rating on the in wall capacitor in your system ?

Jeff Lamb

twocvbloke

White of a UK line to L1, Red to L2, I don't bother with rewiring mine to work with the master socket cap. myself... :)

Ktownphoneco

I just had another thought on the subject since 2cvbloke added the additional information.    Does your system use a 2 conductor line cord, or a 3 conductor cord, providing ring voltage to the telephone set ?

Jeff

Alex G. Bell

Quote from: andy1702 on July 14, 2017, 08:03:00 AM
Being in the UK I don't often find American phones. I just picked up a particularly interesting batch yesterday though as part of a bigger purchase.

Here we have three early Western Electric 500s. Two dated 1952 and one dated 1964. All of these have metal finger wheels. One is complete, while the other two are just missing the card holder.

None of these have come with line cords, so if anyone can tell me how to fit UK cords to these for use on the madern UK system (with the capacitor in the wall socket) I'd be very grateful.

Andy.
If the UK system connects the ringers of all phones in series with a single capacitor those ringers might be relatively low impedance and putting this high impedance ringer in series with them might interfere with their operation even though it probably would itself work.

twocvbloke

Ringers in the UK are wired in Parallel just as the north american types, the difference is they put the capacitor in the socket in the 80s to reduce bell tap (or bell tinkle) as GPO era ringers had no bias springs so unconverted, they tend to ping the bell when a hookswitch is depressed and when another phone on the line is pluse-dialling out...

Borrowing a picture from here - http://telephonesuk.co.uk/wiring_info.htm - you can see how the sockets are wired up...

Alex G. Bell

Quote from: twocvbloke on July 14, 2017, 09:43:25 AM
Ringers in the UK are wired in Parallel just as the north american types, the difference is they put the capacitor in the socket in the 80s to reduce bell tap (or bell tinkle) as GPO era ringers had no bias springs so unconverted, they tend to ping the bell when a hookswitch is depressed and when another phone on the line is pluse-dialling out...

Borrowing a picture from here - http://telephonesuk.co.uk/wiring_info.htm - you can see how the sockets are wired up...
OK, even with the ringers themselves wired in parallel, to prevent what we refer to as "bell tap" it would seem that there would have to be a chain of contacts in each of the phones so that taking any phone off hook would disconnect all parallel ringers.  I don't see how that's possible with the wiring depicted in the diagram.

twocvbloke

That only shows how the sockets are wired (and despite appearances, the cap C1 is wired between pins 2 & 3)...

It's the wiring of the GPO telephones that caused issues, with having a 1.8uF cap per phone, an pulses on the line, generated by the dial of another phone or the hookswitch being closed on another phone, was enough to create a small voltage spike which was enough to trigger current flow through the cap to the ringer, and Ping, the bell gets tapped...

This doesn't happen on north american phones with ringer bias springs as the spring holds the clapper back, without this spring, they too would also tap... :)

Dan/Panther

Can you post more photos of the top phone in the set ?

D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

andy1702

Here's what I've done in the end... Our line cords have 4 cores. Red and white (which are the line), bule (the bell wire) and green (not normally used).

First I tried the method mentioned here http://www.britishtelephones.com/pstconv1.htm#non which didn't work! The bell just gave a really weak tinkle. I think these instructions are wrong because the resistor is normally to go on the 1000 ohm bell circuit on UK phones with 2x 500 ohm coils to make have a value of 1REN instead of their original 4REN. But aren't 500s 1REN anyway? So what's he talking about the resistor for?

Anyway, I put the red/slate wire back where I found it, having taken the resistor out again and coupled the line red to L1, white to L2 and the blue bell wire to G. I did all this without moving any of the original connections and it seems to work.

What 2cvbloke said about just connecting the red and white line connections didn't work for me. The phone didn't ring with those just connected to L1 and L2. I had to reconnect the blue wire of the cord to G to get it to ring.

So it's now working ok, but should I be taking the slate/red wire off  A and adding it onto K to cut out the internal cap? Is the phone running through both the one in the socket and the one in the phone the way I've got it?


Call me on C*net 0246 81 290 from the UK
or (+44) 246 81 290 from the rest of the world.

For telephone videos search Andys Shed on Youtube.

andy1702

Quote from: Dan/Panther on July 14, 2017, 11:43:47 AM
Can you post more photos of the top phone in the set ?

D/P

I tried, but now I'm getting that stupid forum 'security' error. This is despite the fact the photos were all taken at the same time, with the same camera and were all resized with the same software to be the same size!!! It's SUCH a hassle posting photos here! >:(
Call me on C*net 0246 81 290 from the UK
or (+44) 246 81 290 from the rest of the world.

For telephone videos search Andys Shed on Youtube.

twocvbloke

Quote from: andy1702 on July 14, 2017, 11:48:31 AMWhat 2cvbloke said about just connecting the red and white line connections didn't work for me. The phone didn't ring with those just connected to L1 and L2. I had to reconnect the blue wire of the cord to G to get it to ring.

So it's now working ok, but should I be taking the slate/red wire off  A and adding it onto K to cut out the internal cap? Is the phone running through both the one in the socket and the one in the phone the way I've got it?


Given you're getting ringing with the bell wire connected to G, then that means you left the black wire from the ringer on G, which usually gets moved to L1, which would give you the two wire setup as I'd mentioned... :)

andy1702

Quote from: twocvbloke on July 14, 2017, 11:54:19 AM

Given you're getting ringing with the bell wire connected to G, then that means you left the black wire from the ringer on G, which usually gets moved to L1, which would give you the two wire setup as I'd mentioned... :)

Just checked and you're right, that's exactly what I've done. Am I right in assuming it's ok for it to stay there though? the original wiring is a bit on the crispy side, so I don't really want to move anything I don't have to.
Call me on C*net 0246 81 290 from the UK
or (+44) 246 81 290 from the rest of the world.

For telephone videos search Andys Shed on Youtube.