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Chopin

Intriguing ETA 2678 issue

Question

Hello everyone, hope you're doing great!

I have a watch with an ETA 2678 automatic movement. Everything functions correctly but there seems to be a small issue.

When adjusting the hands, at some point, the crown seems to slip just a bit and I think that I can hear a click or two (like something is slipping inside).

It doesn't happen in the same spot from what I can see. It happens once ever 4-5 crown revolutions, maybe more... When it happens the crown itself slips a bit. If I rotate it counter clockwise it doesn't do the same thing.

Also, if I rotate it backwards and then forward again it'll do the same thing in the same area/position.

I'm only posting because I don't really want to take this apart, or at least maybe I can just remove some of the parts and not the whole thing.

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you need to open it to check the teeth of different parts: minute wheel, intermediate minute wheel, sliding pinion. You also need to check the propper sitting of the yoke spring.

Edited by matabog

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Hi   this looks like a problem with the crown or castle wheels could be worn or tooth missing it is also possible the ratchet wheel is either worn or damage in places Is it possible to post a photo of the front and back plates the yoke and spring, lots of possibles probably will need to remove hands and dial to gain access to the keyless work and check the action.

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Have only removed the case back and checked the wheels that were visible and I saw no damaged teeth. I guess I'll have to take it apart when I have more time...

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If the crown feels hard to turn  and considering it slips only in clockwise direction, I say the min train bridge is letting one cog ride/ jump over another

If the crown feels normal to turn it is a broken cog.

Dose it feel harder to turn in clock than anticlock direction?

If the crown feels normal and only get hard to turn when its about to slips,  it is a faulty teeth.

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Everything runs smooth. It's just the crown that slips a bit (and I hear around 2-3 small clicks when it happens) at some point.

Which side should I try to disassemble first ? The dial one or the other ?

PS: I don't mind taking it apart but it's such a small movement...  :(

Edited by Chopin

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Thanks guys... Will give this a try one of these days.

I too was thinking of a broken gear/wheel but was hoping that it might be something else that didn't require part replacement.

Fortunately we're not talking about a Rolex movement so I guess the parts will be easy to find.

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I presume that the correct stem is fitted, and is not badly worn or "egged" i.e. worn to an egg shape rather than round, on one side or at one edge, causing the keyless work to sit "squinty", or the clutch to have excessive travel/play.

Edited by AndyHull

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Alright so I think that I found the problem. The circled gear seems to have the tendency to raise up just a bit when adjusting the hands which, I think, makes it slip from the clutch wheel.

The movements runs smooth but could it be possible that the canon pinion might be a bit too tight ? I kind of have the feeling that it is...

IMG-8125.jpg

How would one loosen up a bit such a canon pinion ?

Edited by Chopin

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Hi Chopin    the cause of the problem has been identified don't for get to check the canon pinion is not too tight this could have caused the problem in the first place by putting pressure on the minute wheel until a tooth gave way.

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I did check the pinion. It was a bit tight but I did loosen it a bit. Not sure what caused the tip of the tooth to break but something was probably too tight, indeed.

Interestingly enough is that it mostly seems to slip only clockwise. Counterclockwise it functions better. Probably because of the angle of the smaller steel wheel that turns the minute wheel and pivots a bit depending on whether you adjust the hands clockwise or anti-clockwise.

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that tooth did not break because of the canon pinion, imho. it interacts with the hour wheel. Maybe the minute and hour hands were interacting at a point in time...

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Yeah I think I found it. Minute wheel #260. Now I have to source one.

Minture bridge looks warped and screw as OH mentioned , wrong screw I think, you should also find out whàt turns hard to cause  gear ride over the pinion.

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When I take out the canon pinion. It all functions as it should. When I add the canon pinion the crown eventually slips and it seems to do so when the small steel gear "reaches" the slightly broken tip of the minute gear's tooth.

I have loosened the canon pinion just a bit but I don't think that it's enough...

Would I be able to make this work by loosening it a bit more ? That damaged tooth is only missing a fraction of it's tip...

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