Certina 25-661 movement - Date driving wheel

[Ced]

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.   

 

[watchweasol]

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

[Ced]

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.

 

 

 

[Plato]

8 hours ago, Ced said:

once the teeth are in contact, the time stops while the balance continues to run.

A loose cannon pinion maybe? 

[Ced]

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 !

 

[watchweasol]

Good well done, it had to be drive failure, you nailed it.   

[ScottNB]

Hey thanks guys! I have a Gubelin watch with a Gubelin A1022 movement which is a re-branded Certina 25-661 and had a very similar problem.  All seemed fine with the watch until around midnight when the seconds hand would stop and  no date flip over . Scratched my head for days on this problem and then found this posting. Got hold of a spare 25-661 movement and replaced the cannon pinion in the A1022. All is working perfectly today! Many, many thanks again for sharing your expertise and knowledge .

[Nucejoe]

16 minutes ago, ScottNB said:

 All seemed fine with the watch until around midnight when the seconds hand would stop and  no date flip over . 

So was the old canon pinion damaged? 

[ScottNB]

38 minutes ago, Nucejoe said:

So was the old canon pinion damaged? 

didn't look to be damaged, just worn I guess

[Nucejoe]

2 hours ago, ScottNB said:

didn't look to be damaged, just worn I guess

When the seconds hand stop, its usually either one of these cases,

1- Oscilator stops as well.

2- Oscilator continues oscilating.

 Case No 2 is the most common, which often is a case of loose canon pinion, in which case you don't need a replacement , just tighten the canon pinion.

Case 1,  Usually points to a damaged part, or many other possibilities. 

Spotting the fault helps improve diagnostics.

Regs