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Improving the Precision of the A7750 Minute Counter


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As you know, the Asian 7750 movement is a copy of the ETA 7750. The Chinese factories have copied all the pieces of the Swiss 7750. However, some pieces are different, some are still compatible, some not, or need modification.

These differences are some times visible in the functioning of the Asian 7750. One of the differences in some movements (there are several factories) is that the minute counter increments one minute before than the Swiss movement. Next video shows the problem. Please check that minute counter moves before the seconds hand reaches the 12 position.

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Guest avitt

Thank you. I wish I had this tutorial handy when I changed out a chrono wheel a few weeks ago...It would have saved me some time (and I also would have used the Swiss part).

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Thank you. I wish I had this tutorial handy when I changed out a chrono wheel a few weeks ago...It would have saved me some time (and I also would have used the Swiss part).

sorry friend.... I am working as fast I can ;)

Francisco.

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Wow...this is amazing mate. Excellent tutorial. This one should become a sticky.

This has been one of my biggest gripes with the A7750 movements....and now thanks to you....there seems to be a solution. Though my watch tinkering skills are non-existant....am sure I can buy the parts and get a watchsmith to do this.

Do any of our modders on-board do this?

Cheers

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Someday.. maybe I can disassemble a throw away movement. this is such a valuable tool .. I need to add it to my fav list so when I have time ..(LOL) I can go through it .. when I am not rested my attention span is very short :p

thanks so much Fransico !!

Aloha~Cheers

L

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Great stuff. Francisco, I wonder if you can comment on this issue I have seen with the A7750 (one of a few reasons I've always swapped out to ETA 7750s).... The hour totalizer moves past the hour mark well before the minute totalizer has gone around 30 minutes two times. In other words, somewhere around the 40 to 45 minute mark, the hour totalizer is already showing 1 hour of elapsed time.

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Great stuff. Francisco, I wonder if you can comment on this issue I have seen with the A7750 (one of a few reasons I've always swapped out to ETA 7750s).... The hour totalizer moves past the hour mark well before the minute totalizer has gone around 30 minutes two times. In other words, somewhere around the 40 to 45 minute mark, the hour totalizer is already showing 1 hour of elapsed time.

It is the first time I have heard that problem! The 7750 movement is so complicated...

Sorry, I cannot imagine what is going on without having a look...

Francisco.

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Well done Francisco.

If I can suggest a different way to make the hole in the seconds hand bigger.

I use small broaches to drill out the hole and then it doesn't need to be glued to the post. The broaches are tapered and you can control the size of the hole and test it as you do the drilling, once it fits the post, you stop.

Here is the type of broaches I am speaking about

Hand broaches

Bergeon 1896-H Assortment of 12 Pivot Smoothing Broaches

Diameters 0.05 to 0.30

BERG-1896-H

$23.30

RG

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Man that was just brilliant. The legitimacy of the forum is unimpeachable with posts like this. I belong to sever gen watch forums and NEVER do we get stuff like this - it's just awesome. As Lanakai said - get me a beater movement so I can start playing. The effort that goes into these posts is evident and appreciated. Man if The Zigmeister and Francisco every joined forces...cue diabolical laughter, while rubbing hands together, "BWAH HA HA HA HA HA!!!"

THANK YOU.

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Well done Francisco.

If I can suggest a different way to make the hole in the seconds hand bigger.

I use small broaches to drill out the hole and then it doesn't need to be glued to the post. The broaches are tapered and you can control the size of the hole and test it as you do the drilling, once it fits the post, you stop.

Here is the type of broaches I am speaking about

Hand broaches

Bergeon 1896-H Assortment of 12 Pivot Smoothing Broaches

Diameters 0.05 to 0.30

BERG-1896-H

$23.30

RG

Hey! I was looking for this reference!

Thanks!

Francisco.

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Great and I mean great tutorial! But what if you want to remove the hands again in the future? You will probably bend or destroy the chrono second hand due to the epoxy is it not?

No really. The strength of whatever glue depends on the surface area of contact. The area here is so small...

Francisco.

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  • 2 weeks later...
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As you know, the Asian 7750 movement is a copy of the ETA 7750. The Chinese factories have copied all the pieces of the Swiss 7750. However, some pieces are different, some are still compatible, some not, or need modification.

These differences are some times visible in the functioning of the Asian 7750. One of the differences in some movements (there are several factories) is that the minute counter increments one minute before than the Swiss movement. Next video shows the problem. Please check that minute counter moves before the seconds hand reaches the 12 position.

This tutorial shows how to solve this problem. Following the steps of this tuto the chrono will work like the next video shows, like the gen ETA 7750.

In some movements no mod is needed. However, in other movements the read of the chrono may be wrong due to this issue. For example, if the correct read must be 2 minutes and 58 seconds, the chrono will show 3 minutes and 58 seconds

Hi

 

Where is the tutorial gone, as i have this issue with my 7750 watch

 

thanks

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