Help converting an F68 ? - UK Vintage Radio Repair and Restoration Discussion Forum

ntreacy · 18th Dec 2020, 6:51 pm

Can anyone help please. My friend just lost her Grandma and was left this old phone. I think it is an Ericsson F68 from what I can see on google. I am interested in converting it for use on a current standard domestic phone line.
I found some old diagrams on this forum but the wiring was different. This phone has 8 terminal options on each side.
Can anyone help me with this?
I have a small amount of electrical experience but not with phones!
Is it possible to convert?
Many thanks in advance.

Nigel

dagskarlsen · 19th Dec 2020, 1:15 pm

Hi, and welcome!
If you have an ohm meter, the ringer motor's dc resistance may be of importance for some systems. Maybe we should start to look at what kind of system you have. If you have a good old landline with a master socket and slave sockets the master socket splits the voice and ringer circuits to 3 wires. 2 are the old 2 wires, and the third is the ringer wire going trough a common capacitor. One wire is for talking, one common, and one for the ringer.

Since we do not have a wiring diagram you could try to put about 3-4.5V between 2 wires of the phone and try if you hear yourselves speaking. (a small 9V battery will also work because of its high internal resistance)

When you have located those 2 and you try to connect them to the 2 wires giving dial tone, you may use the phone, but maybe not receive a ringing signal, but still it is a good start.

When you are there we may figure out more step by step.

dsk

AndiiT · 20th Dec 2020, 4:48 pm

Hi, the closest match I can find for your phone is the Nordfern (RFT) W63a diagram and wiring details, some way down the page here.
It might be worth taking a look on that list to see if there are any similar models too.

Andrew

dagskarlsen · 20th Dec 2020, 7:31 pm

Thank you for that hint. I found one, and a diagram inside:

Converting to UK system with master socket:

Remove original line cord.
Remove any link found between terminals 3 and 4.
Connect a 2.2k resistor to terminals 3 and 4.
Connect red of the line cord to terminal 2.
Connect white of the line cord to terminal 3.
Insulate the blue and green wires of the line cord.

It will probably work without doing whats marked with blue.

dagskarlsen · 20th Dec 2020, 9:55 pm

One more label:

18th Dec 2020, 6:51 pm	#1
ntreacy Diode Join Date: Dec 2020 Location: Llandudno, UK Posts: 1	Help converting an F68 ? Can anyone help please. My friend just lost her Grandma and was left this old phone. I think it is an Ericsson F68 from what I can see on google. I am interested in converting it for use on a current standard domestic phone line. I found some old diagrams on this forum but the wiring was different. This phone has 8 terminal options on each side. Can anyone help me with this? I have a small amount of electrical experience but not with phones! Is it possible to convert? Many thanks in advance. Nigel Attached Thumbnails

19th Dec 2020, 1:15 pm	#2
dagskarlsen Heptode Join Date: Jan 2008 Location: Hakadal, Norway Posts: 643	Re: Help converting an F68 ? Hi, and welcome! If you have an ohm meter, the ringer motor's dc resistance may be of importance for some systems. Maybe we should start to look at what kind of system you have. If you have a good old landline with a master socket and slave sockets the master socket splits the voice and ringer circuits to 3 wires. 2 are the old 2 wires, and the third is the ringer wire going trough a common capacitor. One wire is for talking, one common, and one for the ringer. Since we do not have a wiring diagram you could try to put about 3-4.5V between 2 wires of the phone and try if you hear yourselves speaking. (a small 9V battery will also work because of its high internal resistance) When you have located those 2 and you try to connect them to the 2 wires giving dial tone, you may use the phone, but maybe not receive a ringing signal, but still it is a good start. When you are there we may figure out more step by step. dsk

20th Dec 2020, 4:48 pm	#3
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Help converting an F68 ? Hi, the closest match I can find for your phone is the Nordfern (RFT) W63a diagram and wiring details, some way down the page here. It might be worth taking a look on that list to see if there are any similar models too. Andrew

20th Dec 2020, 7:31 pm	#4
dagskarlsen Heptode Join Date: Jan 2008 Location: Hakadal, Norway Posts: 643	Re: Help converting an F68 ? Thank you for that hint. I found one, and a diagram inside: Converting to UK system with master socket: Remove original line cord. Remove any link found between terminals 3 and 4. Connect a 2.2k resistor to terminals 3 and 4. Connect red of the line cord to terminal 2. Connect white of the line cord to terminal 3. Insulate the blue and green wires of the line cord. It will probably work without doing whats marked with blue. Attached Thumbnails Last edited by dagskarlsen; 20th Dec 2020 at 7:44 pm. Reason: adding text

20th Dec 2020, 9:55 pm	#5
dagskarlsen Heptode Join Date: Jan 2008 Location: Hakadal, Norway Posts: 643	Re: Help converting an F68 ? One more label: Attached Thumbnails