Getting close to TC performance with a standard quartz
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  1. #1
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    Getting close to TC performance with a standard quartz

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    This is my Seiko 7A48-7000. I think it can just about qualify for this forum as it's a direct descendant of the 7A28, which I believe was the first quartz chronograph, and it can be easily regulated. I was lucky to pick up this completely unmarked example which must be about 25 years old. It's not my choice for a daily wear, as I want to keep it near perfect, and the crystal is mineral glass, not sapphire. Plus, it's not very readable - the hands are a bit thin and the date needs a magniying glass. BTW, apologies for having photographed it at exactly New Moon, so that this complication is invisible.

    The regulation is in 0.26 sec/day (95 SPY) steps, so it will always be somewhere in the range of +48 SPY to -48 SPY. The smallest variation I can get is -34 SPY - not too bad, but a bit of cheating can improve on this.

    Unsurprisingly, the watch doesn't have an independent hour hand, so it has to be reset twice a year at DST changes (I'll assume 6-month intervals to keep it simple). So the maximum variation between resetting is only 17 sec.

    Then, by initially setting the watch to 9 seconds fast it will be about 9 seconds slow by the next DST change.

    Voilà! My watch runs at +/- 9 SPY.
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    Re: Getting close to TC performance with a standard quartz

    Having the ability to regulate the timing circuit is certainly a big advantage. As you show, even normal quartz can be made 'reasonable'
    "Forever is composed of nows." - Emily Dickinson

    "The watch has to be surrounded by a history.
    You need more than just a great design. You need to create an atmosphere around the product.
    Who is the company behind it? Why are they using this material?
    People need to be able to identify the watch with themselves. It's based on emotion." - Ralph Furter

    ...that's just my opinion and I've been wrong before and will be again and might be now!

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    Thumbs Up Re: Getting close to TC performance with a standard quartz

    Last time I ran a check on them, I had a dozen or so 7A38's in my collection which were keeping time better than +/- 10s/year. Most had been tweaked at some point, using the 0.26 sec/day rotary step switch (usually only one step either side of default setting) to achieve this. Great movements for allegedly non HAQ.

    Nice 7A48-7000 BTW.

    Not a big fan of moonphase myself, but I've got a couple of the Lassale 7A54-7009 pocket watches.




    The 7A54(A) movement is effectively the same as the 7A48(A) but with gold anodised back-plates.
    Last edited by Seiko7A38; June 8th, 2013 at 17:48.
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    Re: Getting close to TC performance with a standard quartz

    I like those. I assume that the 'pusher' at 6 o'c is purely decorative. Glad you showed the movement; I really didn't want to open mine just for a photo.

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    Re: Getting close to TC performance with a standard quartz

    Quote Originally Posted by chris01 View Post
    I like those. I assume that the 'pusher' at 6 o'c is purely decorative.
    It is indeed purely 'decorative' - a further (useless) appendage to snag the inside of your jeans pocket lining:





    Quote Originally Posted by chris01 View Post
    Glad you showed the movement; I really didn't want to open mine just for a photo.
    I'm sure you could have found one online.



    Most 7Axx series movements: 7A28A, 7A34A, 7A36A, 7A48A all look pretty similar from the back ....
    apart from the gold plated 7A54A and the 7A74A used in the Jean Lassale Thalassa chrono's, that is.


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    Re: Getting close to TC performance with a standard quartz

    Quote Originally Posted by Seiko7A38 View Post
    I'm sure you could have found one online.
    Sure, but it really should have been for my watch.

    Funny thing happened a few months ago: a 7Ax8 was for sale on eBay and was described as fully working except the chrono second hand wouldn't move. The seller had included a photo of the movement and it was clear that the centre spring was displaced from the correct location over the bearing. I sent him a message and he replied to say his watch was now working perfectly. I didn't want that particular watch but I keep wondering if I'd have told him if I had been planning to bid for it.

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    Re: Getting close to TC performance with a standard quartz

    Forgot I had these - a few movement shots from a 7A48-7000 belonging to a chap at work, that I worked on a few months back:





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    Re: Getting close to TC performance with a standard quartz

    Quote Originally Posted by chris01 View Post
    Funny thing happened a few months ago: a 7Ax8 was for sale on eBay and was described as fully working except the chrono second hand wouldn't move. The seller had included a photo of the movement and it was clear that the centre spring was displaced from the correct location over the bearing. I sent him a message and he replied to say his watch was now working perfectly. I didn't want that particular watch but I keep wondering if I'd have told him if I had been planning to bid for it.
    That is the most common (self imposed) fault seen on Seiko 7Axx's - the displaced finger tension spring.
    Usually caused by ham-fisted amateurs and 'professional' high street jewellers alike during battery changes.

    This thread on my forum gets quite a bit of traffic:
    Sticky: The all-too-common Displaced Finger Tension Spring chrono' sweep hand problem
    Last edited by Eeeb; June 9th, 2013 at 01:42. Reason: Removed hyperlink that requires a login (and site registration)
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    Re: Getting close to TC performance with a standard quartz

    Quote Originally Posted by Seiko7A38 View Post
    That is the most common (self imposed) fault seen on Seiko 7Axx's - the displaced finger tension spring.
    Usually caused by ham-fisted amateurs and 'professional' high street jewellers alike during battery changes.

    This thread on my forum gets quite a bit of traffic:
    Sticky: The all-too-common Displaced Finger Tension Spring chrono' sweep hand problem
    I wonder how many 'faulty' 7As are sitting unwanted in drawers around the world. Assuming that you haven't already acquired most of them!
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    Re: Getting close to TC performance with a standard quartz

    I have one 7A38: it was given to me as a pressent in 1985: it is reliable, it has a good accuracy (something like 60 spy) and it is in great shape. At that time it costed around 200$ but, in my opinion, it had a luxury movement that could be found today only in very expensive watches.

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