Two Questions About Valjoux 7750

[CKelly]

Hi,

   I've decided to take a couple of days vacation this week. After fixing a leaky bathtub faucet (some vacation) I started to work on a 7750 movement that I bought especially to practice on. I've worked on watches from Accutron  214 to Omegas and lots in between but never had enough confidence to tackle a chronograph. Bought this movement non-running. Got it going fairly quickly but as soon as I engaged the chronograph it quit. First question is was there one made that used dial screws to hold dial? The normal eta hooks are nowhere to be found. Movement is marked with eta logo as well as 7750, also a v2 mark(if I am remembering properly). Next question is does the big end of the oscillating pinion go in first- toward the dial? That's the way it was when I removed it but looking at the manual I have it seems to show it going the other way. I tried to put it back the way it was but that didn't go well. Sure won't sit up as nicely as one I saw in the video.  

Thanks,

Charles K

[omgiv]

Hi Charles,

That does sound like some vacation :). Congrats on tackling the 7750. It is a great movement. I have never seen a 7750 that had dial screws, but that doesn't mean they don't exist. The dial "hooks" are located on the dial side on the 7750. It should be pretty easy to tell if it is supposed to have screws though. The oscillating pinion should be inserted with the bigger side down. The manual from ETA's website is great and can be downloaded or printed.

The movement stopping when the chronograph engaged sounds like something is binding or not meshing properly. Best of luck and please let us know how it goes. Thanks!!!

[CKelly]

Thanks for the reply. I have the eta animated dvd showing the breakdown of the movement as well as the manual. I looked at the movement again and it is marked as "val" under the balance with 7750 to the side of balance. On the other side of the balance is "v4". Think I said v2 earlier. I'm guessing this must be an earlier version. Yesterday I decided to try to put oscillating pinion in as you said. It took me several tries but finally got it to stand up as in video. What threw me off was as I originally took it out I told myself that I better remember how it comes out so I could put it back and that's what I was trying to do.  I've had to order a few parts. There was a makeshift spring that operates the hour counter that I'm waiting on and the day ring is in Arabic so I ordered one in English. I have gotten a lot of enjoyment out of working on this movement.

 

Thanks,

Charles K

[Geo]

Well done Charles!

It's a good idea to take lots of pictures or notes, especially when you come to a bit where you say to yourself "I'll better remember how it comes out".

[CKelly]

You are right about the pictures. I am currently watching the videos dealing with servicing an old Venus chronograph. Right now I'm really enjoying the 7750 and parts are so easy to find or it. Still wondering about the dial screws instead of hooks.

Thanks,

Charles K

[CKelly]

Hi All,

   Just wanted to update you a bit about what I've done so far and ask your opinions. So far I've cleaned, oiled and reassembled the movement. I haven't put dial or hands on it yet as I'm still waiting on day ring. Decided to try it out so I engaged the chronograph and it ran until about ten seconds after the minute counter clicked and stopped. Every time I tried it same thing happened, stops about ten seconds after minute counter clicked. Since it runs well until chronograph is engaged I kind of thought there might be a bad tooth on large second counter wheel. (If that were case why wouldn't it stop after running just ten seconds, should be same place on wheel?) These teeth are very small too see even using 16x magnification. Then I remembered that the teeth of the oscillating pinion and center second counter wheel are supposed to have a bit of space between them when engaged. Very hard too see this. What I did then was to back the clutch spring cam off until the center sweep counter stopped. Then I slowly turned it back until second counter started again. Gave it another fraction of a turn to insure teeth engaged properly with no slipping and stopped. So far it has ran for over an hour with no stopping. The clutch spring cam would need to be rotated another 20 degrees to be where it was set when movement was stopping.

Thanks,

Charles K