Francisco

double posting

I think you have a modified movement. True A7750 has the configuration 12, 6, 9. If you hace another lay-out...the extra gears jump when you press the chrono button. No solution. Francisco.

No good news.....

Yes, be careful...hands are specially bad...the worst are Datytona... pure butter....

Hi: I was told that during a date base backup some of my tutos were lost. I have to upload them again. I will do it..however now I am on holidays. Francisco

I will track the watch I repaired.... In this case the teeth seemed a bit shorter....

I guess so (90% sure). I used an Asian part for the replacament. However, just today I am going to buy the Swiss replacement. Francisco

No turotial needed...just buy this piece and replace the damaged one. Easy work! If this is the problem! Francisco

I like that watch because there is no date loupe. A very beatiful watch..congratulations! Francisco

I am still thinking of offering or not this mod. The problem is the cost of manufacturing and setting. Too expensive now.

sorry...no idea..I sold the watch. I only have the pictures...

I did mod mine: SUMMER BEACH WATCH

I have just repaired one 6497 with this problem. It was the keyless work winding pinnion. Francisco

no. a watchmaker lathe means a precision lathe. It can do the same as a bigger lathe, with more precision and, as it is smaller, with smaler pieces. Francisco

milling, making gears, cutting, polishing...

why not?

Thanks! It is a mod that requieres expensive tools... but I think it is interesting to show how these mods are done. Francisco

The “ratchet wheel driving wheel”, reference 32.033, is a gear of the automatic winding system of the 7750. In some cases this gear will finish with some teeth damaged, as seen on this picture took by Zigmeister: This failure can be produced by frequently manually winding a watch with a 7750 movement. If this failure happens the watch will show a poor power reserve. The ETA 7750 replacement is not compatible with the Asian 7750. The difference is the size of the two pivots of this ratchet wheel. The Swiss spare will not fit in the jewels, as the diameter of the pivots is larger. Here a picture of the Asian ratchet wheel: Next picture shows one of the two pivots that are different: This is a picture of the another wheel face and of the pivot that has smaller diameter in the Asian wheel. The marked pivots have the following dimensions: Asian 7750: 0.19 mm Swiss 7750: 0.27 mm Therefore, the is a difference of 0.08 mm, 8 cents of mm. This difference is large enough to not to use the Swiss replacement, as the pivot cannot fit the jewel. There are three options to use the Swiss part: 1.- To exchange the central part of the ratchet wheel (steel, silver) that it is fitted on the wheel (brass, golden). That means using the central part of the Asian, fitting this part in the Swiss. This task is explained here: http://www.replica-watch.info/phpBB3/viewt...=59&t=53355 2.- To fit the ETA jewels in the Asian plates. I have not research if these jewels are available. Anyway, this is not an easy task. 3.- Modifying the pivots of the ETA ratchet wheel, to reduce the diameter. This task is shown in this tuto. This task requires an extreme precision. It is difficult to show you how small these pivots are. I try ii in the following pictures: First, the size of the gear. The pivot is not visible in the next picture, due to its very small size. On this zoomed image it is possible to see the pivot. A watchmaker lathe will be employed to reduce the pivot diameter. With a good watchmaker lathe a precision better than 0.02 mm is possible, so we can do this task. First step is to measure the ratchet wheel, as shown, it has a diameter of 6.76 mm. Therefore, a collet of 6.8 mm is used: Next picture shows the wheel fastened by the collet in the head-stock of the lathe: Another image to show the vey small size of the pivot: To reduce the diameter a precision milling disk will be employed: The disk is connected to the milling attachment of the lathe: Next step is adjusting the lathe. The milling disk only has to polish the pivot, not other parts of the wheel. We move the disk closer to the pivot until they are touching. In this moment we know we have to polish 0.04 mm, because the total reduction will be 0.08 mm in the pivot diameter. As this task requires so high precision, the scales of the lathe has not enough precision. One of these scales is shown in this picture: We need an external indicator, which has a real precision of 0.01 mm. Next picture shows the indicator, located to measure the distance we move the disc to the pivot. Once the disk is brushing the pivot when it is rotating, the dial is set to 0. Then we are ready to turn. However, the motor is not employed. Just turning by hand as this video shows, to be more precise:

yes, lathe is not cheap, but hours and hours of fan are waiting for me

This story begins when a friend of mine sent me her watch, a Maurice Lacroix with a missed screw of the bracelet, lost a lot of time ago. Well, it is not a beautiful watch

What a good eye! Yes, the arm seems to touch the bottom plate. Francisco

Yes, probably that watch is an unique design. On the other hand...have you considered that hands can touch the glass? Francisco.

Thanks! I answer there... Francisco

I have no experience on this field..so I cannot give any opinion. many people is talking about the ring.... the ring is not the problem itself. The problem is the total height of ring + DW. A cheap ring helps..but the mod of the DW is still there. Francisco

What is the improvement? Will we need still to service the watch after 4/5 years? If so..no improvement for our case. Francisco.