Question about Sea-gull ST25 movement

Thread: Question about Sea-gull ST25 movement

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  1. #1
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    Question about Sea-gull ST25 movement


    I have the below watch (Seagull M308S with ST2528 movement). The watch has a small seconds hand at the 6 o'clock position.


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    When I look closely at the seconds hand on my watch, I can see some choppiness and irregularity in the movement. It is very, very subtle, but visible. It does not appear to affect timekeeping. I most often see the choppiness between the 1 and 4 o'clock position on the subdial, but it is not always there and it appears randomly in other places as well. I have tried holding the watch in different positions to see if this causes any noticeable variation, but it does not. I read elsewhere that the ST25 is set up for a directly driven center seconds hand.
    Does this mean that my watch, with the seconds hand at the 6 o'clock position, has an indirectly driven seconds hand? If so, could this be the reason for the choppiness--perhaps caused by slack in the gears? I read that some movements with an indirectly driven seconds hand have a flat spring that keeps pressure on the gear to eliminate this choppiness. Does the ST2528 have one of these springs? I am new to mechanical watches and do not know much about movements. I did some reading online before posting this, which led me to believe the choppiness could be caused by slack in the gears, a loose spring, or just by poor quality control in manufacture. Any information you can provide is most appreciated. I am not necessarily going to fix the issue (unless it gets worse) but I am interested in learning more about the cause. I would also like to know if this watch has a directly or indirectly driven seconds hand.

    Thank you!

  2. #2
    Mod. Russian, China Mech. Chascomm's Avatar
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    Re: Question about Sea-gull ST25 movement

    That all makes sense to me but unfortunately I don't know exactly how power is transmitted to the indirect seconds hand, even after reading this detailed description:
    17jewels.info - Sea-Gull ST2503

    One possibility is that the second hand is simply mounted on the centre of the 'flying wheel' thing seen on some open-heart versions, which seems to be driven at its perimeter but I can't figure out how. Anyway, this would be rather different to the 3rd-wheel-to-pinion arrangement common to Vostok, Miyota and DG movement.

    Experts please comment!
    Chascomm
    Moderator, Russian Watches & Chinese Mechanical Watches Forums
    (no, I am not going to list all my watches here)

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    Re: Question about Sea-gull ST25 movement

    Quote Originally Posted by Chascomm View Post
    That all makes sense to me but unfortunately I don't know exactly how power is transmitted to the indirect seconds hand, even after reading this detailed description:
    17jewels.info - Sea-Gull ST2503

    One possibility is that the second hand is simply mounted on the centre of the 'flying wheel' thing seen on some open-heart versions, which seems to be driven at its perimeter but I can't figure out how. Anyway, this would be rather different to the 3rd-wheel-to-pinion arrangement common to Vostok, Miyota and DG movement.

    Experts please comment!
    Chascomm, thanks for your reply and for the link. You might be right about the seconds hand being attached to the "flying wheel"--that's a good suggestion. I know that the ST2528 was the basis for the 2011 f72 project watch, and I am hoping someone on here has seen that movement disassembled and can comment on how the seconds hand is driven. Thanks again!

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    Re: Question about Sea-gull ST25 movement

    I have the watch in question. Mine has no choppiness. Can't help you with you quest to find out why. I can say that I've dropped mine on the concrete floor before and the second hand has been very choppy and inconsistent. Would even stop on occasion when it reached the 11 o'clock position. Sent it off for repair and eight weeks later it's running like a dream. Good luck!

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    Re: Question about Sea-gull ST25 movement

    Quote Originally Posted by Bucks View Post
    I have the watch in question. Mine has no choppiness. Can't help you with you quest to find out why. I can say that I've dropped mine on the concrete floor before and the second hand has been very choppy and inconsistent. Would even stop on occasion when it reached the 11 o'clock position. Sent it off for repair and eight weeks later it's running like a dream. Good luck!
    Out of curiosity, did you send it to China for repair or have it done locally? I have only had mine for about two months, and I know that it took a beating during shipment. The seller shipped it with no padding whatsoever and it arrived broken. I sent it back and asked for a new watch, but they sent me the same one which they apparently had repaired. Nonetheless, the watch appears to be in good shape, and it runs well (except for this slight stutter in the seconds hand which I am trying to figure out...)

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