Jump to content
  • 0

ETA 7751 triple full calendar; service, tips, tricks, watch-out fors, do's and don'ts advice please .....


Endeavor
 Share

Question

Hello All;

Got myself a nice little project; a triple full calendar 7751 with papers + box from first owner. The gold-plated watch (Berney-Bloneau S.A.) was purchased on 06 Nov. 1995, worn only on social events, never been serviced and never been opened ! (πŸ™‚)

A do assume it's a standard grade 7750 (?)

7751-1.thumb.jpg.b742c5d1a6da0251747510ce24df63c5.jpg

(crown pulled out to prevent the watch from running)

7751-2.thumb.jpg.ff90fda7b5718121b532b679cf494060.jpg

On the timegrapher the movement runs with straight lines. Amplitude DD & DU around the 230 degrees and about 190 degrees in the vertical positions.

As far as I'm aware it's mostly a 7750 but before taking it apart, I like to fully understand the calendar works and perhaps its pitfalls; the do's and most importantly the don'ts.

- Any advice were to look-out for when disassembling the calendar works ? Any notorious "jumpers" underneath the calendar plate / disks?

The ETA Technical communication describes how to assemble the calendar driving wheel (position day-finger and month-finger) and some checks & adjustments.

- When assembling the calendar works are there any other points I've to be aware off ...... ??

My plan is to take pictures of the disassembly / assembly for a walk-through ......

Hope to hear πŸ˜‰

Β 

Β 

Β 

Β 

Edited by Endeavor
  • Like 1
Link to comment
Share on other sites

9 answers to this question

Recommended Posts

  • 0

There's not too much to fret over if you've done a regular 7750 before. There are two wire click springs on the calendar plate that can jump, and 4 jumpers. Two use springs mounted on the plate, and two the wire springs shared with the moonphase advance lever and corrector. The jumpers for the date and year look identical, and they are, in spite of the manual showing different part numbers, so don't worry about mixing them up.

Β 

If you've done a 7750 then you are already familiar with the spring for the hour counter hammer and zero lever, that one is always fun to put in place. There is a flat wire spring for the day corrector here, which is easy to overlook or think that it's secured in the plate, but it comes right out. The manual makes it clear how to orient it when reinstalling. The date advance wheel doesn't need to be oriented like the pair of wheels in a regular 7750 day-date, it advances everything in order without any fuss. Pay attention to the minute wheel- it has a little cap on the pinion which needs to go over the hour wheel teeth. This is easy to miss and will lock things up if not installed correctly. Normal 7750 doesn't have this.

Β 

Otherwise just follow the (very good) manual for lubrication and assembly. They say not to service the barrel but of course you can and should if not replacing it. On a watch this old it might be a good idea to replace it along with the cannon pinion and reverser for the automatic and possibly the rotor bearing. Do the adjustments for the moonphase corrector (again well explained in the manual), the difference between locking up and not working at all is a very small adjustment.

Edited by nickelsilver
  • Like 3
  • Thanks 1
Link to comment
Share on other sites

  • 0

Excellent, such an answer I was hoping for πŸ‘ Thanks a lot !!

Do you have any tips for removing the hammer-spring (45) without scratching the edge of Automatic device bridge (44)?

I know that there is a hole in it, but lifting the spring over the edge of the bridge and releasing the tension doesn't seem to, without making a small scratch, work very well for me. I also tried to carefully remove the bridge, holding the hammer down and then lift the spring ........ bit more tricky of having a "flyer".

What's your way of doing it?

BTW, can you see from the movement whether it's a standard grade?

Link to comment
Share on other sites

  • 0
5 hours ago, Endeavor said:

Excellent, such an answer I was hoping for πŸ‘ Thanks a lot !!

Do you have any tips for removing the hammer-spring (45) without scratching the edge of Automatic device bridge (44)?

I know that there is a hole in it, but lifting the spring over the edge of the bridge and releasing the tension doesn't seem to, without making a small scratch, work very well for me. I also tried to carefully remove the bridge, holding the hammer down and then lift the spring ........ bit more tricky of having a "flyer".

What's your way of doing it?

BTW, can you see from the movement whether it's a standard grade?

You can put a piece of Scotch tape on the bridge, the translucent one, not the clear one (it sticks just enough but no residue), to protect from scratching with the hammer spring. I put both spring and hammer before the bridge; it almost always stays put (chrono in "run" mode so the hammer isn't on the chrono wheels). IΒ  can only remember once in the last few years having one that didn't want to do that.

Β 

Can't tell what grade it is. Even standard grade tends to hit chronometer level rates, or close to it, even after 30 years of being run without servicing. It's not the prettiest chrono but it's a runner.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

  • 0

Thank you, I'll try the "running"-mode tape-method πŸ˜‰

Yes, it's amazing how accurate you get these 7750's to run when, if all else good, you spend time to adjust the Etachron properly.

I think I know enough to get started πŸ™‚

Thank you for your help so far ...... πŸ‘

Link to comment
Share on other sites

  • 0
11 hours ago, nickelsilver said:

Master

Unlike some who like to think they are, you truly are ! πŸ˜‰ πŸ‘

The 7751 is back together, ticking & showing no less than the 11 functions very happily.

Awaiting new crystals to complete the case and for the final walk-through picture ....

Edited by Endeavor
  • Like 2
Link to comment
Share on other sites

 Share



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • I have a few questions on the use of a (lever-type) jeweling tool in the adjustment of jewel endshakes, as I have never done this before. 1. If the endshake is too much or too little, how do you choose where to adjust the endshake? Do you adjust the endshake on the train bridge, or the main plate, or both? How do you decide which is the best? 2. When inserting the pusher into the spindle of a lever-type jeweling tool, such as a Favourite, is the best practice to take out the entire spindle from the tool frame to insert the pusher? And likewise, take out the entire spindle from the tool frame to remove the pusher? Or is it perfectly ok to insert or remove the pusher when the spindle is still inside the jeweling tool frame. Which way is safer/ best practice. 3. Is there an attachment to the base of the jeweling tool to hold the mainplate or bridges? I don’t seem to see any for sale, new or otherwise. Can I make one?
    • In the USA, you could try: https://www.jewelerssupplies.com/ or http://www.julesborel.com/ Cousins in the UK might be a possibility (although Waltham is a US watch, I'm sure some of them made it across the pond). https://www.cousinsuk.com/ Mark also has a list here: https://www.watchfix.com/category/watch-parts-tools-suppliers/watch-parts-tools-suppliers-us/
    • Yup. It's like the song from The Greatest Showman.... Never Enough! Never, never...
    • Somewhere else the group weΒ  we had a discussion on finding lift angle which is similar to this. I've found that using a certain type of highlighting pen with liquid ink worked much better than any other color because it would fluoresce under UV light. So you just dim the lights down and it glows really brightly and it makes it really easy to see the amplitude. There's another way to do it but unfortunately it's astronomically expensive and no I don't know how expensive it is but I think of we would have to ask it's beyond our price range I do wonder if we will for a clever whether we could do something similar? In any case they put a Mark on the balance arm the use a camera system to film it and then they can measure the actual physical amplitude and they can also determine the left ankle. Thishttps://www.witschi.com/en/products/wisioscope-2/ The experience with This Group Has Been They Usually Don't Work the Best. And Then There Is the Other Minor Little Thing Whether You Have a Timing Machine or an App You Going to Have To Figure out How Many Beats per Hour This Is? Because the Age It May or May Not Be 18,000 Fortunately the Timing Machines Usually Have All the Standard Frequencies That It Probably Is and You'll Just Have To Figure out Which One It Is. Β 
    • I bought the balance staff removal tool first then realized I needed the staking set. lol. Buying more tools never seems to be a problem. Matt
×
×
  • Create New...