Author Topic: WE 500 7D Rotary Rebuild  (Read 3801 times)

Offline sbreen

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WE 500 7D Rotary Rebuild
« on: March 07, 2011, 10:02:18 PM »
Hello,

I'm looking for some help. My Western Electric 500 series phone's rotary was sticking so I decided to take it apart and clean it up. After tearing apart and cleaning and putting back together it no longer works.

I believe it has to do with the plastic piece on one of the gears. I'm not sure of the terms, but there is the piece that spins and creates the pulses, and the piece that sticks out that I think is not positioned correctly.

I can't figure out where I went wrong and am looking for some help - here are the photos.:

A side topic, don't think it is related, when it was working the phone would chime after dialing each number. It always worked and I thought it was a nice feature but don't think it was supposed to do that.

Thanks in advance for any help,
Scott


Pictures:
IMG_1795_Photo1_EndState.jpg : After spinning dial and it's end state. In this state when I pick up I get no dial tone.

IMG_1796_RotaryCranked.jpg: Turned the dial for number 0 but before release

IMG_1797_ToGetDialTone.jpg: After dial there is no dial tone, but tapping phone or jiggling rotary it will end up in this state after which there is a dial tone.





Offline Phonesrfun

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Re: WE 500 7D Rotary Rebuild
« Reply #1 on: March 07, 2011, 10:14:07 PM »
There is a very specific position the nylon cam needs to be in while at rest.  If you have another 500, you can use it as an example.  If not, I believe Dennis Markham has some photos he has done that show the position.  It would not be easy to talk you through it.  In this case, a picture is worth a thousand words.

There are two ways of adjusting the cam.  One is to take the gear train apart and try to anticipate where it will wind up at rest, and then reassemble the train.  This is always a frustrating experience for me.  I believe Dennis has a way of prying the cam off and then pushing it back on facing the right way.

Dennis??
-Bill G

Offline sbreen

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Re: WE 500 7D Rotary Rebuild
« Reply #2 on: March 07, 2011, 10:46:59 PM »
There is a very specific position the nylon cam needs to be in while at rest.  If you have another 500, you can use it as an example.  If not, I believe Dennis Markham has some photos he has done that show the position.  It would not be easy to talk you through it.  In this case, a picture is worth a thousand words.

There are two ways of adjusting the cam.  One is to take the gear train apart and try to anticipate where it will wind up at rest, and then reassemble the train.  This is always a frustrating experience for me.  I believe Dennis has a way of prying the cam off and then pushing it back on facing the right way.

Dennis??

A picture may be worth a thousand words, but I'm pretty certain your words were enough. Thanks for the quick reply. I should have noticed the cam had 4 phases - I'm 90 degrees out of phase. I tried a quick experiment it seems like once I fix that it will work.  I'll take a before and after close up after I get to it tomorrow and post it for future reference. I'll probably just take it apart and put back together as opposed to pulling the nylon off the gear, that seems high risk.

Thanks,
Scott


Offline Dennis Markham

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Re: WE 500 7D Rotary Rebuild
« Reply #3 on: March 07, 2011, 11:36:47 PM »
Bill, you're correct.  I'll have to track down the photo.  The small plastic lobe should be in the 10:00 position or maybe 9:30-10:00 when at rest.  This pushes those contacts together to make dial tone when the phone is off hook and the dial at rest.  It is very easy to simply take a flat head screw driver and carefully pry upward under the plastic pieces.  The lobe will come off at the top.  You can reposition it properly and save yourself from having to fiddle with the gear train to align the gears.  There are four pieces associated with this.  From the top there is the lobe (that is out of position), beneath that is a very tiny washer, below that the other plastic piece with the arm that separates the contacts for pulsing and finally at the very bottom is another washer type piece of copper.  It has a bend in it which causes it to keep the plastic piece above it from resting on the bushing.  It also has a break in it so that in essence it is "C" shaped but nearly closed at the opening.

In the attached photo you can see the proper position for that lobe.

Offline JorgeAmely

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Re: WE 500 7D Rotary Rebuild
« Reply #4 on: March 08, 2011, 12:01:02 AM »
It is always nice to go back to the basics to understand why it doesn't seem to work.

The pair of contacts on the left, actuated by the black nylon block attached to the main gear are there to mute the speaker when you actuate the dial. It does that by closing a pair of contacts and thus placing a short across the speaker.

The second pair of contacts, actuated by a cam (same shape as a car camshaft), pulse the line current (upon which your conversation is superimposed) from on to off and back to on, depending of what digit you dial. That means that at rest, in order to sustain your conversation, these contacts need to be closed. In addition, in order to guarantee the correct dial timing, the cam has to be pointing just slightly above the nut that holds the main gear in place.

In some place there is an ITT diagram that shows this in detail. Found it! It is attached.
« Last Edit: March 08, 2011, 12:04:22 AM by JorgeAmely »
Jorge

Offline sbreen

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Re: WE 500 7D Rotary Rebuild
« Reply #5 on: March 08, 2011, 08:31:29 PM »
Dennis, Bill & Jorge,

Thanks for all the excellent information. Problem solved. Attached are two photos with the phone in the initial / end state, one when the phone was not working and one after correcting the problem thanks to your replies.

IMG_1801_INCORRECT.jpg - Before correction, not working
IMG_1802_WORKING.jpg - After correction and working

Scott