Strange Problem of the Crown on ETA7750

[rckh]

Dear All:

This is the 3rd times I have got the same problem on my ETA7750 crown. Before they have problem; they work fine; winding smooth & keeping very accurate time as they should be. After 6~8 months later. I found they just stop in my winder. Then I found that once the crown had been tighten. The automatic winding won't work; if I unscrew the crown & put them back into the winder. They'll work perfectly......Any one have any idea about this problem? Seems all my A7750 didn't have this strange problem.

Best Regards,

Raymond

[RWG Technical]

It sounds like your reversing click wheel is sticking, the only fix is to take the movement apart, clean the reversing wheel and autowinder gears, lubricate them, and put it back together.

If you feel resistance when handwinding, DON"T do it, you will strip the teeth from the gears and ruin the autowinder.

RG

[Francisco]

Following The Zigmeister comments, you may have a look here:

http://www.rwg.cc/members/Repairing-manual...ind-t93138.html

Francisco.

[rckh]

Dear The Zigmeister & Francisco:

Thx for your comment & reply! When the 2nd time this problem appear. I brought it to my local watchsmith & he told me that the problem was came from the bad crown design. I wonder a gen eta7750 also got same kind of problem 3 times....The many point is: after I un-tighten/ un-screw the crown. It work perfect & automatic winding normally; even I try to manually wind it. It's very smooth. once the crown screwed back. It won't wind anymore. So, is it the problem came from reversing wheel; not from the crown?

Best regards,

Raymond

[kbh]

Here's a possibility.

As the o-ring in the top of the crown gets older and more compressed, you are screwing the stem farther into the movement. Maybe this is binding up something inside the movement. If it all works properlywhen you unscrew it a half turn to a turn, I'd try replacing the o-ring.

[freddy333]

I am assuming (from the screwing/unscrewing) that this is a Rolex rep. Rep Rolex crowns are crummy, at best. So if you are having any problem that relates to the crown or crown tube, the 1st thing I would do is replace the stem with an ETA 7750 stem (julesborel.com or cousinsuk.com) & the crown/tube with gen parts (ebay or your watchmaker, if he has a Rolex parts account).

From your description, another possibility is that you may be screwing the crown down too tightly - if so, screw the crown down only until you begin to feel it bottom-out & then STOP. Do not tighten it. Many people think that they must screw the crown down very tightly to make it watertight. That is NOT true. Once the internal rubber gaskets sandwich/seal between the tube & the inside of the crown, the seal is made. Any further tightening beyond that point is only going to deform or damage the gaskets.

Another possibility is that the stem may be too long, so that when the crown is screwed down it is applying too much pressure on the gearing. Either way, the only way to know for sure if either of these is the problem would be to leave the crown unscrewed & see if the problem occurs again.

[redbird]

Appx how many turns should a 7750 be getting on a watch winder to reach full charge (or by me sitting there and spinning the thing in a circle)? Sounds like the tootsie roll owl maybe? Any way to tell when it's fully wound?