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onzenuub

Repairing when crown does not change day / date (7750)

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onzenuub

And again a fabulous one from Francisco.

 

This is a Porsche with A7750 movement. The day/date cannot be changed using the crown. However, the change works at midnight, as following videos shows:

 

 

Therefore, given the problem that this watch has, there are two possible sources: a keyless work problem or a problem in the piece that pushes the two day/date wheels (double corrector). So we know where to have a look.

 

The screwed case back is removed:

 

4046276168_0001587d3b_o.jpg

 

The movement is removed:

 

4045531221_3a64a69d8b_o.jpg

 

Time to remove hands and dial:

 

4046276246_fd7fe11948_o.jpg

4046276280_c2ba8713a0_o.jpg

 

It is very easy to remove the day wheel:

 

4045531359_6006047219_o.jpg

 

Red arrow in following picture shows the piece that pushes the day/date wheels (double corrector) when the crown is rotated.

 

4046276354_ef05af6fe7_o.jpg

 

As it was said before, this piece is one candidate to be the source of the problem. When I touched it to examine it… it is broken:

 

4046287692_5258956010_o.jpg

 

Red Arrows in previous picture show two parts of the double corrector that are released. One is a washer, and a gear that pushes the wheels. The gear is assembled through the hole shown on the picture. Below the hole, there is a gear that is connected to another gear that rotates when the stem is rotated.

 

To remove the double corrector (the part of it that is not released) we have to remove the date wheel. Following pictures shows the parts to be removed in order to free the wheel:

 

4046276392_abc739ff8f_o.jpg

 

The date wheel has been removed:

 

4046276434_9546f0a1ec_o.jpg

 

And now we can remove the broken part. Following picture shows the gear that rotates when we rotate the stem/crown to change the day/date. This gear connects to the gear of the double corrector:

 

4045531479_b865d1f8f8_o.jpg

 

The broken double corrector:

 

4046276496_ec52d9b2c1_o.jpg

4046276518_2d320e30d1_o.jpg

 

I tried to repair the double corrector…. With no success… not a very durable solution…

 

4046276550_e976f99f99_o.jpg

 

Therefore, we use a new double corrector. Cousinsuk’s reference:

 

VAL77502569: Valjoux 7750 2569 Double Corrector £5.90

 

After replacing the new double corrector we have to assemble all the parts, just following the same steps back. Watch is repaired, as the following video shows:

 

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juju38

very instructive post

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KeNnY

A W E S O M E ! :Thinking:

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Wiz

Thanks a lot for putting this together, I'm sure it will save me some watchsmith expenses in the future :Thinking:

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tissotman

A very good topic as ive had i few problems with similar watches.

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MikeMcNair

how doe one get a hold of this "fransisco" person? i have an A7750 i need fixed and i cannot do it myself. i would LOVE to send it to this guy.

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KBH

Francisco, is mostly on RG and RWGjr. But he's in Spain so I'm sure you could find someone closer.

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onzenuub
how doe one get a hold of this "fransisco" person? i have an A7750 i need fixed and i cannot do it myself. i would LOVE to send it to this guy.

 

 

For the next 10 days he is on a vacation.

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GenTLe

I've the exact same problem on a brand new IWC 3717.

Is there a way to understand in advance (before to unassemble the watch) if the problem is at keyless or at double corrector level?

I'd like to order the part in advance and not leaving the watch unassebled for a week or so while waiting for the piece.

 

Thanks GenTLe

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