7D Dial function after rebuild

[Tom B]

I've stripped and cleaned a number of 7D dials, but I  recently rebuilt one and now it won't break dial tone - I should know this, but what have I done wrong?

[JorgeAmely]

The normally closed contacts are not opening for some reason. Do you have this problem for all digits?

[Tom B]

Jorge
It seems to be moving as it should - cam lobe correctly set etc - contacts are opening and closing when i dial - what am I missing?

[Dennis Markham]

Tom, can you post a photo of the back side of the dial?

[Tom B]

Dennis
I hope these pictures are clear enough

[JorgeAmely]

Do you see the contacts on the right hand side of the picture open and close as the dial winds down?

[Tom B]

Hi Jorge
They close at the start of the dialling sequence and then open at the end

[Dennis Markham]

Things look normal in the photo.  When you turn the dial "off normal", do the contacts on the left side of the photo make contact?  They need to close while the dial is not at rest.  The right contacts should pulse during the return.  I think you said they are doing this.  The only other thing is to ask where the wires are connected at the network.

[Tom B]

Dennis
All seems as it should be. That's why I 'm confused - simply, could the dial be shot?

[Dennis Markham]

I doubt the dial is shot....if the wires are properly attached to the network, and the contacts are doing what they're supposed to be doing the only other thing I can think of is that one of the solder joints could be bad where the wire is soldered where the contacts attach at the top.

I suppose it could be a switch contact but if it was working before you worked on the dial then there is a problem with the dial.  Do you have another similar dial you could attach to this phone to see if it work?

[Tom B]

That was my thought also - I 'll let you know the outcome - thanks as always to you and Jorge for taking the trouble

[Dennis Markham]

Double check your wires at the network.  Blue to F, Green to RR, White to GN, White to R.

[Bill]

I'm an old radio guy, so the first thing I would do is disconnect all the wires from the dial, and then use an ohmmeter to confirm that the contacts are indeed opening and closing. Occasionally, the eyeball test doesn't work due to a thin film of oxide on a contact.

Don't try to clean the contacts with an abrasive (sandpaper) or an implement (knife blade). Do you have any spray contact cleaner? In the old days, we used to say that you could clean these contacts by pulling a white index card through them, especially after giving them a shot of cleaner. I never had a lot of luck with this approach ...

Bill

[LarryInMichigan]

I have had problems where dialing did not break dial tone, and the problem was not always in the dial.  On one phone (WE 500), there was a short in the ringer which was keeping the line "off-hook".  On other phones, wires/spades were touching where they should not have been.  I would suggest carefully checking all of the connections and possibly disconnecting the ringer.  A shorted ringer capacitor would cause the same effect.

You might also see what happens if you push and release the hook switch plungers quickly a few times.  If that does not break dial tone, there is a short or incorrect connection somewhere.


Larry

[Russ Kirk]

I agree with NOT using abrasives.

Here is a photo of a WE 265C CO switch tool.  I think the switch techs of yesteryear used this tool for cleaning and adjusting contacts.  It has a contact burnishing attachment.  Touching it with my fingers it feels smooth. But using my lips I feel that it is slightly abrasive, perhaps at a grit of 1000 or higher.  

I knew I kept this 265C tool for a reason, I only had to wait 25 years to show it off!

Russ.....