I recently got myself a GPO 746. A very old rotary dial pulse dialling
type telephone.

Usually, to dial a number you just put your finger in the hole and
turn it. HOWEVER. The thing doesn't "turn back" correctly. It'll give
a pickup as if I just picked up the phone again. I think this is
because it's not going back as fast as it should.

If I pull a number and push it back into position manually, a bit
faster. It'll dial that number! So I think the retaining springs
inside are a bit loose. Would anyone here know how I could either
tighten this spring or would I have to get a new spring?

Thanks very much in advance!
Dan

wrote in message
ups.com...
I recently got myself a GPO 746. A very old rotary dial pulse dialling
type telephone.

Usually, to dial a number you just put your finger in the hole and
turn it. HOWEVER. The thing doesn't "turn back" correctly. It'll give
a pickup as if I just picked up the phone again. I think this is
because it's not going back as fast as it should.

If I pull a number and push it back into position manually, a bit
faster. It'll dial that number! So I think the retaining springs
inside are a bit loose. Would anyone here know how I could either
tighten this spring or would I have to get a new spring?

Thanks very much in advance!
Dan

There is usually a 'bucket and weight' centrifugal governor on the dial
return, which is worm driven. The end float of the shaft is adjustable with
a screw, and I have known this to be over-tightened by people such that the
governor is too tight for the return spring to move it. Likewise, if the
grease on the governor drive and bearings has gone hard and sticky, this can
also jam or restrict it.

The dial assembly is easily removed to work on it. There is a single screw
at the bottom, which needs only to be loosened. The dial then hinges up and
away from its mounting cradle at the bottom, and then lifts out at the top.
The dial return speed can be checked, once you have it on the move again, by
dialing a zero, and then saying out loud "One-thousand-one-hundred-and-one".
That's without any gaps in the words and just at normal talking speed.

The dial should hit stop just as you finish speaking. The exchanges are (
certainly used to be ) fairly tolerant of the pulse repetition speed, but if
it is too far out, a mis-dial can occur. If the spring is broken , it
usually goes at the looped end-anchor. By heating it in a gas flame, you
might be able to bend a new anchor on it. The other option might be to use a
section of an old clock mainspring.

It's been a long time since I worked on one of these, so it's all from
memory, but I think I'm about right. Hope it helps.

Arfa

Hi Dan

I made a pulse dialer once and this may help you.

Return time from Zero dialing to rest position should be about 1.1 seconds in America and I think is a bit different in Europe. I remember tone pulses at 10 pulses/second.

I think you should clean the inside clutch which makes uniform return rather than tighten spring and adjust the press screw to get this rate.

Hope this work..

Regards

John_H

On 11 May 2007 12:19:44 -0700, wrote:

I recently got myself a GPO 746. A very old rotary dial pulse
dialling
type telephone.

Usually, to dial a number you just put your finger in the hole and
turn it. HOWEVER. The thing doesn't "turn back" correctly. It'll give
a pickup as if I just picked up the phone again. I think this is
because it's not going back as fast as it should.

If I pull a number and push it back into position manually, a bit
faster. It'll dial that number! So I think the retaining springs
inside are a bit loose. Would anyone here know how I could either
tighten this spring or would I have to get a new spring?

Thanks very much in advance!
Dan


This is probabbly the best site for old UK phone info
http://www.telephonesuk.co.uk/phones_1960-80.htm#746

Circuit etc.
http://www.samhallas.co.uk/repositor.../0000/N846.pdf

Dial type 21 (basically the type 12 dial with plastic case and clear
finger plate)
http://www.samhallas.co.uk/repositor.../0000/N581.pdf

When a rotary dial has been unused for years it will generally become
slower in operation (or not work at all) due to lubrication drying
out, or somebody has played around with the tensioning of the governor
arms (or both). The only way to fix it is to totally strip it and then
re-assemble. This means you have to know what you are doing and how to
set it up and adjust it if it is to work properly. Techs in training
usually spent a week performing this operation under supervision
before they became proficient at dial refurbishment.