where to attach alarm latch

jtvx

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My trusty Junghans trivox mechanical from the 90s is rattling. Upon disassembly, I found a spring and a latch(for the alarm?) loose inside. The clock used to have a low ding, pre-alarm feature(is there an official name for that?) which stopped working a while back. I presume this is what this latch is for. I am trying to figure out where to attach those 2 parts. Suggestions?

alarm-spring2.jpg front.jpg parts-view1.jpg parts-view2.jpg
 

roughbarked

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This is a later model than the ones I worked on.
Bivox is two alarm tones, Trivox is three. Vox = voice or sound.
The alarm starts out with a quiet sound and gets louder then louder again.
Now the parts do look as if they are part of the system though how they got to fall off is beyond me. Junghans made everything tight. It was often hard enough to get the parts off. Therefore it is difficult to imagine parts falling off.
Is there a collar on the alarm arbor for this lever to sit on and is there room for a clip to hold it there?
 

Dick C

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Never seen one; however I would start by looking at possible wear of the metal where the spring may have rubbed.
 

jtvx

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Ahhh, hence the name Trivox, thank you!

I tinkered with the alarm mechanism some more, trying to work out the mechanical movement of the 3 stages.
There seems to be the 3 possible positions of the 2 alarm latches.(maybe that is the tri from the Trivox?)

When I initially opened the case, one of the 4 top brass hex nut is also free. I am not certain which one now.
While I don't see a collar for the lever to sit on. Is it possible the lever sits under the nut in the blue circle?

My guess (sofar) from looking at the spring length:
- attach one end of the spring to the red circle
- attach the other end of the spring to the small hole on the lever
- hook the big hole of the lever to the screw post under the hex nut(blue circle)
(I tried this setup; however it didn't seem to make sense once the pieces are in, maybe I have the lever backword?)

When you were servicing the older Trivox models, anything in particular stood out?

Would anyone with a working Trivox share some internal photos?

possible-functions.jpg position3.jpg position2.jpg position1.jpg
 

Dick C

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Ahhh, hence the name Trivox, thank you!

I tinkered with the alarm mechanism some more, trying to work out the mechanical movement of the 3 stages.
There seems to be the 3 possible positions of the 2 alarm latches.(maybe that is the tri from the Trivox?)

When I initially opened the case, one of the 4 top brass hex nut is also free. I am not certain which one now.
While I don't see a collar for the lever to sit on. Is it possible the lever sits under the nut in the blue circle?

My guess (sofar) from looking at the spring length:
- attach one end of the spring to the red circle
- attach the other end of the spring to the small hole on the lever
- hook the big hole of the lever to the screw post under the hex nut(blue circle)
(I tried this setup; however it didn't seem to make sense once the pieces are in, maybe I have the lever backword?)

When you were servicing the older Trivox models, anything in particular stood out?

Would anyone with a working Trivox share some internal photos?

View attachment 648861 View attachment 648862 View attachment 648863 View attachment 648864
With what you suggested, blue to red, is the spring the correct length?

When I look at the part, it appears that on one side the big hole shows some wear as does the small hole?
 

roughbarked

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With what you suggested, blue to red, is the spring the correct length?

When I look at the part, it appears that on one side the big hole shows some wear as does the small hole?
These are important questions.
I'd suggest winding up the alarm and triggering it. watching how it works. See if you can pick vox 1, vox 2 and by then it should be beginning to become apparent where vox 3 goes.
 
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jtvx

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Yes, the lever has more wear on one side, see detailed lever photo attached.

I took off all 4 hex nuts and only the yellow and blue sites have visible wear marks.
I ruled out the yellow post because it would mean stretching the spring into high tension.

I attempted to hook the lever on the blue post in the following 4 orientations:
- position 1, 2, 3 both
a) lock the lever in place
b) prevents that long cam hook from moving freely.

- position 4 is the configuration I described in the previous red/blue post.
The spring length fits and gives just enough tension to engage the long hook.
However, it bothers me to see the spring bent touching the alarm striker.
Currently there is no wear marks on the body of the spring itself.
Yes, I have tried putting the spring on either sides of the lower hook that is part of the alarm striker.
(position 4 photo shows the spring on the right side of that hook).
In both cases, the alarm will no longer trigger.

For many times, I wound up the alarm spring and then rotated the alarm dial to trigger the ring.
Without the missing pieces attached, it goes directly to a full stage 3 ring.

What else should I try?

lever-scratchside-up.jpg lever-scratchside-down.jpg possible-functions.jpg hex-nut-post-yellow.jpg hex-nut-post-blue.jpg lever-on-blue-scratchside-up-position1.jpg lever-on-blue-scratchside-up-position2.jpg lever-on-blue-scratchside-down-position3.jpg lever-on-blue-scratchside-down-position4-attached.jpg
 
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Dick C

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Did you try the last photo with the piece 45 degrees clockwise? Could the tab be a stop of some sort?
 
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Dick C

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It appears from one photo that the movement is B 71 or B 7..

Also, I found the complete clock in a 1999 Junghams catalog listed as model 107.7000.00

Perhaps this can be used to further identify the movement.
 

shutterbug

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The obvious things to me is that the spring attaches to the smaller hole on the metal piece and the metal piece screws onto something else. I would be looking for a threaded hole and a corresponding small hole or a pole with a groove where the other end of the spring hooks.
 

jtvx

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Pictures 7 or 9 look to be closest.
The spring needs to go between the two small holes on the levers that have them?
Did you try the last photo with the piece 45 degrees clockwise? Could the tab be a stop of some sort?
The obvious things to me is that the spring attaches to the smaller hole on the metal piece and the metal piece screws onto something else. I would be looking for a threaded hole and a corresponding small hole or a pole with a groove where the other end of the spring hooks.
Thank you for the suggestions!

  • rotated the lever 45 degrees clockwise on the last photo (position 4 scratch side down). However, with the tension from the spring it won't stay unless the hex nut is screwed down tight to prevent play. The result was the same.
  • flipped lever so the scratch side now facing up. But the larger end of the lever(the half hexagon shape) is preventing the long hook from moving freely. No effect in triggering the alarm.
Examining the lever in more detail, It became clear that the scratch was from the the brass hex nut.
This means the scratch side of the lever should face up.

After much tinkering on the blue pole(the bent spring still bothers me), I put the lever on the green pole.
The locking tab, spring position and length now all look surprisingly natural. The spring dampens the

alarm striker as those 2 pieces gradually move clockwise during the initial phase of the alarm trigger.
This is very exciting! We are definitely on the right track. Unfortunately, I am still only getting the stage-3 full blast alarm.

possible-functions.jpg lever-on-green-scratchside-up-position5.jpg
 
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roughbarked

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Yep. Don't know why I didn't see that before. Your initial images show the shadow of that piece on the alarm guard(shiny bit).
So you now have it in the right place.
I'm interested in the lever that has the big E clip on it. Can you describe what you see this lever doing?

You see, I cannot get away from the fact that the clock came to you with bits loose yet the nuts were in place. This indicates that someone has been inside playing. In my mind, there may be a pinion missing where the sharp end of the lever rests? Also, the lever with the hook end seems out of place unless that hook end does something.
 
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jtvx

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I have been its original owner for 2 decades. The nut at the green site was one of the rattling pieces. I secured it back in place upon opening because it was obvious where it came from. This all begin to make sense now, the tug and release of the spring from each alarm over the years eventually freed those 3 pieces, a design flaw.

trivox-alarm-parts.jpg
The lever(A) under the E-style retaining ring is part of the voxing mechanism.


When the alarm spring(R) is fully wound:
trivox-position1-fully-wound.jpg
  • lever(A) tugs the white plastic piece(D) and they top out together SW.
  • tiny compression spring(C) between the vertical hook(B) and the plastic piece(D) is relaxed, at it max length; [vertical hook(B) is part of lever(A)]
  • long hook(J) is in the east most position, stopped by the vertical hook(J) and post(E).
  • the short hook(F) is also in the east most position, stopped by post(E).
  • extension spring(X) is relaxed with no tension


... over the course of the alarm, long hook(J), short hook(F) progressively rotates towards lever(A),


after the alarm goes silent
trivox-position2-ring-complete.jpg

  • lever(A) and the plastic piece(D) are in the NE most position
  • long hook(J) and short hook(F) are both stopped by the plastic elbow(D) and post(E)
  • tiny spring(C) is fully compressed
  • extension spring(X) is in tension
the ring hammer(G) is directly secured the the snooze hook(N)

I still do not understand how the long hook(J), the short hook(F) and spring(X) work together to achieve the 3-stage action.

Do you still have a Trivox in your collection?
 
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jtvx

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Thank you for digging up the Trivox!

This clock has not been serviced elsewhere. This is the 2nd time I had opened it in 20 years.

Could it be this piece?
p1.jpg p2.jpg
It is actuated by a lever connected to the hammer. This sprocket also has 15 teeth and I do not see any other gear with that number.
See
VIDEO

I am really curious now of how the 3-stages are engaged and I plan to fully document it once I understand its inner workings. Would it be possible to share a video of the alarm mechanism in action?
 
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roughbarked

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Sorry. That video site was not working for me.
The wheel you are pointing to in the photos is the equivalent of the alarm escape wheel.
The pinion I refer to has fallen off at some stage and if it isn't still inside the clock then have a look on the floor. They usually don't come off easily.
 
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jtvx

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Haha. nothing on the floor here, the roomba must have eaten it, 10 years ago. Oh well.
 

roughbarked

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At least now, you know what it looks like and can seek one out or even make your own. It doesn't have to be exactly the same. All that would do would make it ring slightly differently. This pinion ticks off certain phases of the alarm until it falls over and rings fully.
 

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