Jump to content

Tag Heuer 7750 movement (chronograph wheel)

AP1875
 Share

Recommended Posts

AP1875 WRT Addict

AP1875

Posted
Posted

I was offered a Tag Cal 16 at a good price so I bought it to practice on. All functions were working correctly.

I have serviced a 7750 previously about 18 months ago, took me a while but no issues.

I’ve finished assembling the chronograph, installed the hammer and clutch springs however when the pinion is pressed against the chronograph wheel the chronograph does not turn. Everything locks up which causes the balance to stop.

The chronograph wheel does not spin freely with the chronograph bridge installed when I try to turn it with a plexi stick. It feels rough and tight. The reverser and minute chronograph wheel turn freely. The jewel is still in place on the chronograph bridge.

I’ve taken the chronograph apart and rebuilt it twice, tried 2 chronograph wheels, doesn’t seem like there’s much I can adjust.

Hit a bit of brick wall. Any advice on further checks welcome please.
 

 

 

 

IMG_7405.jpeg

IMG_7404.jpeg

nickelsilver Distinguished Member

nickelsilver

Posted
Posted

You're in the stop position there, so the brake should be pressing against the side of the chrono runner wheel. Put it in the run position, make sure the rocking pinion is correctly in it's hole in the mainplate, and in its bridge (and right-side-up- little teeth to the chrono runner), and that the friction spring is correctly in position under the chrono runner. There, with the rocking pinion pulled away, the chrono runner should turn freely.

  • Like 1
AP1875 WRT Addict

AP1875

Posted
  • Author
Posted

Hi @nickelsilver this is after I have tried to run the chronograph, I have stopped it and removed the clutch spring, hammer spring and removed the chronograph bridge for reference.

I have rebuilt it this evening, when I press start after 10 seconds or so the balance stops. This is because the pinion is pressed against the chronograph wheel but the chronograph wheel won’t move freely.

I press reset the pinion moves away and the balance runs. Pinion orientation is correct.

 

IMG_7412.jpeg

IMG_7413.jpeg

IMG_7414.jpeg

IMG_7415.jpeg

IMG_7416.jpeg

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing


  • Recently Browsing

    • No registered users viewing this page.

  • Topics

  • Posts

    • AndyGSi
      Reusing mainsprings in an automatic and slipping

      By AndyGSi · Posted

      I've found with Russian watches they don't stick to the Swiss numbering system. The problem with the mainspring is that as this is a dual barrel system they're very small compared to most automatics. If you look on Cousins the weakest 1.45mm high spring is 0.085mm which could be too powerful for this movement and is also designed for a 7.5mm barrel. If you then look at the GR Catalogue and work back from the GR3930X, this is the first auto with correct power rating. Although you'd probably have to go back further to this one to make sure it fits.    
    • TimepieceTinkerer
      Title: ETA 2836-2 Not Ticking After Pallet Fork Replacement – Need Assistance

      By TimepieceTinkerer · Posted

      Hi all, I’m currently working on an ETA 2836-2 movement. I replaced the pallet fork with a new one (ETA2801710, sourced from CousinsUK). After full reassembly and lubrication, I’ve encountered a strange issue: The movement is fully wound and has power. When I fit the balance assembly, the movement does not tick at all—completely dead. When I remove the balance, the gear train suddenly releases and spins freely, indicating power was present. The pallet fork just “floats” without snapping side to side—almost as if it isn’t even there. No interaction with the escape wheel is visible at that point. However: Before fitting the balance, I checked the pallet fork manually — it was working as it should, clearly interacting with the escape wheel. I’ve inspected the pallet bridge jewel (where the pallet fork sits) and everything looks normal. No signs of misalignment or obstruction. I’ve rechecked everything I can think of and I’m completely out of ideas. Has anyone seen this behaviour before? Any suggestions would be greatly appreciated. Thanks in advance! TT
    • dnhb
      Loose pinion

      By dnhb · Posted

      Thanks for the prompt response. I apologise for not stating the issue more clearly. The problem is that - what I now know I should have called - the centre wheel is not being turned by the pinion (which is driven by the barrel) with which it shares the arbour (1st photo above). The pinion & arbour are indeed reverse threaded but the arbour (the 'screw') is clearly damaged ('rounded' rather than 'sharp' threads) with swarf evident. When the pinion is screwed on there is only enough connection to prevent the pinion being lifted off but not enough to stop it turning on the arbour. Is a (reversible) repair (threadlocker?) possible in the short term while a replacement centre wheel assembly is sought so that the viability otherwise of the watch can be established?
    • BertsBoy
      Straightening a bent seconds pivot

      By BertsBoy · Posted

      Sorry this is a bit late but how did it go for you?   I'm working on a 561 with a similar issue. Cheers, Martin
    • rozcoeb
      Help! Mainspring releasing power!

      By rozcoeb · Posted

      I'm struggling to put it back so I'm going to watch a tutorial so may be a few hours.
×
×
  • Create New...