Jump to content

Advice Need On A7750 Chrono Fix

Lolo1972sg

By Lolo1972sg
in Watch Repairs Help & Advice

 Share

Recommended Posts

Lolo1972sg New Member

Lolo1972sg

Posted
Posted

Hi folks

I have a cheapie rolex homage with chrono functions. The movement inside is probably an a7750 (opened once a few years ago and can't remember exactly).

Recently, I tested the chrono function and the chrono started but would not stop, ie, when I press down on the stop chrono button, no click sound is heard and it does nothing to stop the chronometer. Same thing when I tried on the reset chrono button, no click sound neither.

Can anyone kindly advise what can be done by myself (a newbie) or any quick fix please.

Thanks a lot. :)

Link to comment
Share on other sites
Lolo1972sg New Member

Lolo1972sg

Posted
  • Author
Posted

Hi folks

I have a cheapie rolex homage with chrono functions. The movement inside is probably an a7750 (opened once a few years ago and can't remember exactly).

Recently, I tested the chrono function and the chrono started but would not stop, ie, when I press down on the stop chrono button, no click sound is heard and it does nothing to stop the chronometer. Same thing when I tried on the reset chrono button, no click sound neither.

Can anyone kindly advise what can be done by myself (a newbie) or any quick fix please.

Thanks a lot. :)

Any advice please?

Thanks

Link to comment
Share on other sites
Lolo1972sg New Member

Lolo1972sg

Posted
  • Author
Posted

Its probably a Chinese copy of a 7750, terrible movement but good to learn on.

Yes. Very highly likely an Asian clone of 7750.

I am thinking of opening it up and check the chrono button. If anyone has any advice on what to look out for, it would help and I would be much appreciative please.

Thanks in advance

Link to comment
Share on other sites
Lolo1972sg New Member

Lolo1972sg

Posted
  • Author
Posted

Do not assume all Asian movements are bad movements.

Check this blog about (some) A7750 having protection for adjusting date at any time, which ETA doesn't have.

http://watchguy.co.uk/valjoux-7750-terminal-date-change-feature/

Hmmm... Interesting and I did not know about that.

Anyhow, how about anything on the chrono issue I have please? Any help?

Thanks

Link to comment
Share on other sites
jdm Distinguished Member

jdm

Posted
Posted

Anyhow, how about anything on the chrono issue I have please? Any help?

One can't know without looking. To set expectation rights, chrono is all about levers and springs and is considered advanced watchmaking, plus spare parts for Asians movements are practically impossible to get. Of course you could be lucky and able to sort it out easily.

Link to comment
Share on other sites
 Share
Go to topic listing


  • Recently Browsing

    • No registered users viewing this page.

  • Topics

  • Posts

    • Mallard
      Vintage pocket watches from e-bay (winding stems needed)

      By Mallard · Posted

      Hi nickelsilver, thanks for the great explanation and the links! I'll take a good look in the article.  Especially this is great news to hear! Looking through forums and youtube videos I was informed to 'fist find a case and then fit a movement for it'. But seems that's not the case for pocket watches at least?  I guess I should be looking to find some 'male square bench keys' for now. I was thinking of winding the mainspring using a screwdriver directly, but I found a thread that you've replied on, saying that it could damage the spring. 
    • Waggy
      2813

      By Waggy · Posted

      Murks, The rate and amplitude look OK, and the amplitude should improve once the oils you have used get a chance to move bed-in, also I notice that you are using default 52 degrees for the lift angle, if you get the real lift angle (assuming it's not actually 52) this will change your amplitude - maybe higher, maybe lower. I notice that the beat error is a little high, but not crazy high. At the risk of upsetting the purists, if the balance has an adjustment arm I would go ahead and try and get this <0.3 ms, but if it does not have an adjustable arm then I would probably leave well alone. Just my opinion.
    • Murks
      2813

      By Murks · Posted

      Hi everyone on my timegrapher it showing this do a make anymore adjustment someone let me know ?    
    • Waggy
      Epilame / Fixodrop

      By Waggy · Posted

      Maybe I'm over simplifying this and I'm a little late to the discussion, but just by my looking at oil when I use it on a treated cap jewel  the oil stays in one nice bubble, but when I don't it spreads out to the edges of the jewel. I'm not sure (but could well be wrong) but the analogy of a waxed car and rain is accurate in this case, the wax is very hydrophobic and repels the water, however, the process epilame works by is a different physical process based upon cohesion/adhesion (oleophilic) not repulsion (oleophobic)  at least as far as I have read/observed. If one were to use a oleophobic substance equivalent to wax (hydrophobic) then one would need to create a donut shape to fence in the oil, however if one used such a strategy with a epilame which is oleophilic then the oil would sit on the ring of the donut and not in the 'donut hole', exactly where you don't want it. Even if the oil is smeared then the oleophilic epilame should pull it back to the center (see diagram below). Reference For interest the chemical in epilame is 2-(PERFLUOROHEXYL) ETHYL METHACRYLATE, CAS NO: 2144-53-8
    • Waggy
      Dg 2813

      By Waggy · Posted

      Looks lint the teeth on the hour wheel aren't meshing with the teeth on the calendar intermediate wheel, maybe the hour wheel is sitting on top of this instead of meshing?        
×
×
  • Create New...