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Mendes458

Its gone a bit wrong again

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Mendes458

So I had my first A-level exam today. Yesterday, however, I planned to use my Chrono to time how long to spend on each question. E.g. five marks 5 mins. However, after a 25 marker (25 mins) I pressed the reset pusher and the minute subdial reset to a random point. I also learnt that the scale on the dial is not the true scale, so it's pretty useless regardless. But I'm hoping that someone else has had this problem and there is an easy fix. 

I just had it serviced by Nick, who has done an excellent job, but it would be the second time I would have sent it back as the automatic winding was messed up before which he took back and fixed. I don't want to go straight back to him because he might think I'm taking the piss. 

It is an Asian 7750 Valjoux Working Chronograph movement, 28800bph.

If needs be I might have to send it back but I'm hoping there is fix.

Thanks in advance for all your help.

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Jasonbaylee

I rarely use the chrono functions. It is especially wrecking if activated between 2200hrs n 0200hrs if u have your date correctly set otherwise it creates the same havoc on your watch even it is in the daytime


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GenTLe
I rarely use the chrono functions. It is especially wrecking if activated between 2200hrs n 0200hrs

There is absolutely no connections between the day/date automatic change function and the chrono. Seriously.

About the OP problem: either the minute hand slipped on the pinion (probable if the second hand continue to properly reset to 12) or you have a problem with the reset hammer of the chrono: I am remounting a 7750 these days and I have a similar problem caused by the hammer (4) not properly pushing (with the two 5s) against the reset cams (3 and 2) of the minute (3) and second (2) chrono gears:

PIC86O.jpg

 

In my case I suspect it's just a lack of play between the plate where the hammer is pivoted and the one that is screwed over it.

 

 

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Jasonbaylee

Really Gentle???

Geee... Thk you


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Mendes458
3 hours ago, GenTLe said:

either the minute hand slipped on the pinion (probable if the second hand continue to properly reset to 12

I presume It is this as all the other hands correctly reset to 12

I also presume I don't have the skill to fix it so it may have to go back to Nick

Thank you GenTLe for all your help and thanks to Jasonbaylee for getting involved :D

 

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Monkey_Business
3 hours ago, GenTLe said:

There is absolutely no connections between the day/date automatic change function and the chrono. Seriously.

About the OP problem: either the minute hand slipped on the pinion (probable if the second hand continue to properly reset to 12) or you have a problem with the reset hammer of the chrono: I am remounting a 7750 these days and I have a similar problem caused by the hammer (4) not properly pushing (with 5 and 6) against the reset cams (3 and 2) of the minute (3) and second (2) chrono gears:

PIC86O.jpg

 

In my case I suspect it's just a lack of play between the plate where the hammer is pivoted and the one that is screwed over it.

You are god

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GenTLe
You are god
Ahahah, no, let's call the things for what they are... I'm just a passionate about watches.
There are many people here that know things better than me (@Rolie to cite one) and are just not as prolific as me with posts. And many others that do the same tasks I do and simply don't speak about them.

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GenTLe
Really Gentle???

Geee... Thk you


Sent from my iPhone using Tapatalk
Yep :) They (the day/date changers) are triggered by the hour gear train on the upper part of the movement. The chrono instead engages directly from the main gear train and all the main parts (apart the hour counter clutch and reset hammer) are in the lower part of the movement.

Oh, there is a third possible cause for the problem: if the 7750 is a modified one and the minutes counter is not at 12, then there are transfer gears to move it from the 12 position to whenever it has been placed. In that case it can be a sloppy hearing between these gears the one that made the minutes counter out of synch.

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Jasonbaylee

Thank you for that insight Gentle


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