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Certina 25-661 movement - Date driving wheel


Ced

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Hello all,

I have been servicing a Certina 25-661 movement. Everything went fine until I reassembled the calendar work.  

The movement is running well, the date can be changed manually via the time setting position...but, when letting the movement run, it won't change the date automatically. The tiny teeth of the date driving wheel would push against the teeth of the date wheel, but won't move any further, while the balance wheel is still running.

I wonder whether I missed some proper alignment of the date driving wheel or if there is not enough power/torque coming from the mainspring.

Thank you for letting me know what you think about this issue.

Cedric.   

 

IMG_20210615_172155.jpg

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The fact that the watch keeps running whilst the date change remains locked and fails to change would suggest to me that there is a lack of traction or slippage in the calender work, Does the watch continue to work in this condition although the date remains unchanged. I would remove and closely inspect the drive components and check for wear on the points and changer.

If you have a look at the Ranfft site  it will list all the family variants of his movement.

attached is the tech sheet with calender parts should you need it.

1806_Certina 25-65, 25-651, 25-652 (2).pdf

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Hello !

I did not think of it that way, thank you for your recommendation and technical information, I will disassemble and scrutinize the calendar work.

To answer your question, once the teeth are in contact, the time stops while the balance continues to run.

On this picture, we can see the date wheel moved slightly, but remains stuck at that point.

Will let you know the outcome,

Thanks again,

Ced.

IMG_20210616_123038.thumb.jpg.6453977b45cd50fefba69d16c68f66d9.jpg

 

 

 

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Alleluia !

Upon close inspection of the calendar work, I could not find any anomalies.

Therefore I replaced the canon pinion with another one coming from a scrap movement.

And yes, it works !

Many thanks !

 

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