7750 was working, I touched it, now it isn't....

[AP1875]

Pretty frustrated with this, I have a clone 7750. Everything was running well, however the chrono hand didn't completely reset to 0, literally a fraction off so I thought id reseat it so it was in the centre

I was given some advice by another member here to hold down the reset button whilst gently pressing the hand back on, this would mean the cams were in the correct place and the chronograph hand should then reset to 0 after running.Great shouldn't take me more than 30 minutes.

I removed the movement, popped the hand off and put it back on following the advice given. No drama.

Now when trying to run the chrono the middle seconds hand just springs forward and stops dead. When I reset it, it goes back to its original position.

What have I done wrong? 

At first I thought I hadn't pushed down hard enough and the hand was slipping so it was just springing forward, but it resets so has a good hold of the pinion.

Have I pushed too hard? I was super gentle with it so don't think that's the case. 

I'm using a movement holder with the buttons at the side, and also the screws that sit in the base (what are they for?). Could I have knocked something out of place on balance side?

These aren't  cheap movements and do run well, so it's obviously me......

 

Edited March 25, 2019 by AP1875

[AP1875]

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[AP1875]

Looking again, this spring doesn’t look right. Would that be inline with my problem?






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[m1ks]

Unfortunately I can't assist with the chrono problem but those bits in the bottom of the holder are supports for when pressing hands, cannon pinion etc on, they can be adjusted.

Having a closer look at your pics, the spring certainly doesn't look right, i'd get it under a loupe and look for somewhere it would seat.

Edited March 25, 2019 by m1ks

[nickelsilver]

That spring hooks around the eccentric screw next to it. It keeps the rocking pinion in contact with the chronograph runner when the chrono is engaged.

[saswatch88]

the screws support the pinions when pressing hands on. the hand being off could have just been you not pressing on perfectly. as far as clone 7750 goes they really arent top notch when compared to the eta, the chinese have no quality control and the chrono arms always have more play in them compared to the eta because of the way they are riveted together, make sure there is no play in the rivets.

 

but the spring is 100% your issue it may be popping out when hit the start button look at the pic i attached the spring should but up against the pinion arm. that spring pushes the arm and allows the pinion to make contact with the center wheel which makes the chrono run when you hit the start button, then pull back when stopping chrono.

 

also i have to ask is the rolex real? if so go spend $400 and get an official valjoux 7750. you will thank me later

 

 

Edited March 26, 2019 by saswatch88

[jdm]

6 hours ago, saswatch88 said:

also i have to ask is the rolex real? if so go spend $400 and get an official valjoux 7750. you will thank me later

Even on a genuine Rolex fitting a non-Rolex movement would be very wrong in terms of maintaining correctness, and hence, resale value.

[AP1875]

Thanks for your advice and pointing me in the right direction, I’ll watch one of Marks 7750 videos to help install the spring.

The 7750 movements of today are a lot better than they were 10 years ago. I have some that have been reliable for 3-5 years and still going well. The only real issue is the sec @ 12 movements with the extra gears.

Definitely not a real Rolex, I just buy the clones to practice removing the hands etc trying not to damage/mark the parts. A 7750 will not fit into a Daytona case. This one has frozen sub dials. I have a clone 4130 which is really very impressive.



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[saswatch88]

4 hours ago, jdm said:

Even on a genuine Rolex fitting a non-Rolex movement would be very wrong in terms of maintaining correctness, and hence, resale value.

agreed. didnt think the rolex was real but if it was and he didnt have the rolex movement and the ETA is always better than a clone.

AP yes mark does have a video on the 7750, and there are a ton of other videos as well. update when you fix that spring