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Thread: Seiko 7548-7000 and an Horotec Flashtest

  1. #1
    Craftsman Bodo's Avatar
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    Seiko 7548-7000 and an Horotec Flashtest

    Been tinkering with this bit of kit for a little white and so I'll provide some info.

    Here is a picture of the Flashtest.


    The toy has some nice features; the ability to detect an impulse and set rate, check the power consumption of the circuit and movement, check battery voltage and also check resistance of the coil.

    I first started cleaning the movement up and I must say that the cleaning fluids are much more effective. The mainplate here looking nice and clean.


    Swapped over after installing the crown setting mechanism and ready to install the centre wheel and bridge.


    Train wheels installed along with reset lever.


    Bridge installed and so now is the time to check the coil.


    As you might be able to see from this image there was a sign that someone had slipped and hit the coil with a driver most likely and therfore I was worried the resistance would be impacted.




    We would need to see a resistance that's between the min and max values as per the movement, which would be between 2 and 4 kilohms.


    A coil that shows damage would end up causing us issues in that power consumption would rise or the rate of the watch would be compromised. If the resistance is just under 2kilohms, it might be feasible to allow it to stay in the watch and adjust the rate accordingly, but the movement would consume more power than necessary leading to a shorter battery life. Of course if the coil's connectors had separated then we would see infinite resistance and the watch wouldn't run.

    As can be seen from this picture we are right in the middle of spec for the coil's resistance at 2.91 kilohms.



    The Flashtest is becoming a favourite!

    Next up I'll install the circuit and switch over to get on with the calender side.




    Which, again, is looking spotless thanks to the new cleaners. They might be overkill if you can mix your own chemicals up, but I can tell new that I could not do without the L&R111, and the rinses seem to do an excellent job at... rinsing, but also drying quickly without leaving any residue.

    Once the calender side is installed it was time to check the movement's power consumption. I haven't the results of the test with crown out, but they were in spec, and so with crown in and the movement's total power consumption to be measured what we want to see is a draw no higher than 2.4 microamps crown in, and 0.9 microamps with the crown out. The circuit is still being powered with crown out as the quartz oscillator is still running, meaning the movement quickly jumps into action as soon as the crown is pushed back to the 0 position, but it is significantly less consumption than when crown is in and the movement is ticking.



    With the negative contact held with rodico I could take a picture of the readout! :)



    Great news! Next I want to install the dial and hands and get it ready to be cased up, I'd already cleaned and installed the crystal etc, but just a few snaps taken and I'll post those pictures below, but before that and whilst it's outside of the case I wanted to measure the rate and adjust accordingly. The stronger the pulse signal detected by the Flashtest the more accurate the rate displayed will be. A new battery was installed before installing the dial and hands and the battery was just checked quickly to show we are getting 1.5V out of it. It's a brand new battery, so I don't need to worry about how much life is left in it, aslong as it wasn't a dud straight away!



    The Flashtest counts down from 60 seconds and then displays the results after a further 3 second wait.


    Pretty good! But I wanted to do a little better, bear in mind that these movements are affected by temperature, so what we might see here may not equate to a real world accuracy test, but let's at least see how much better it can be. Adjusting the trimmer on these is almost more delicate than a balance regulator!



    Too far!



    Pleased with that!



    Chapter ring and gasket ring installed, you can see the lip on the inside edge the gasket sits against.


    Retaining ring pressed home.



    A lovely, and very accurate, 7548-7000!

    I hope my understanding is accurate here, but if there are any electronics gurus that want to correct my understanding of say the coil and what happens with an out of spec measurement that would be very interesting.

    Thanks, TZ!
    Last edited by Bodo; 7th March 2018 at 23:34.

  2. #2
    Master Thewatchbloke's Avatar
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    I see you finally bought one, my nagging paid off

  3. #3
    Craftsman Bodo's Avatar
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    :) yup! Tis very useful, thanks, Duncan!

    With hands installed and inside case I'm getting -0.03 spd.


    One more adjustment:
    Last edited by Bodo; 7th March 2018 at 21:01.

  4. #4
    Craftsman geran's Avatar
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    That's a great piece of kit.

  5. #5
    Master Mouse's Avatar
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    Quote Originally Posted by geran View Post
    That's a great piece of kit.
    I don't need one, I can't afford one either ......... but I now want one!

    Thanks for posting OP

    ;-)

  6. #6
    Master Thewatchbloke's Avatar
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    Quote Originally Posted by Bodo View Post
    With hands installed and inside case I'm getting -0.03 spd.
    Having it cased and the hands installed will make no difference, the circuit will pulse at the same rate regardless - even if there's no train installed! It will fluctuate very slightly during normal running but the one thing that will affect it is temperature.

  7. #7
    Grand Master
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    Hadnít realised these Seiko quartz movements had a trimmer! Definitely not something to fiddle with if you donít have the Flashtest machine.

    How much does this wonderful machine cost?.......I guess it wonít be cheap.

    Paul

  8. #8
    Craftsman Bodo's Avatar
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    It wasn't cheap! Cousins have them, Paul. I don't want to think about the price too much. :)

  9. #9
    Master huytonman's Avatar
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    Interesting and useful post - more so for me as I dismantled a 7548 movement 18 months back, cleaned it ready for reassembly then other things took priority and now when I look at the components Im not sure I can put it back together! Your pics etc are a huge help though so I'll use them as inspiration to have a crack at it. To the comment about not fiddling with the trimmer, yes, dont! I did once and that was it regards regulation on that movement, the smallest adjustment sends the rate off some way and getting back proved impossible.
    Keith

  10. #10
    Grand Master
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    Digital camera is always your best friend when dismantling a watch! I keep all the pictures on the computer, I never rely on my memory. Close up pictures taken on macro setting are a must.

    Paul

  11. #11
    Craftsman Bodo's Avatar
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    Few more detailed pictures here Keith that may help.

    http://forum.tz-uk.com/showthread.ph...ssion-Complete

    Also Martin's superb posts that helped me a tonne...

    https://adventuresinamateurwatchfett...ry/seiko/7548/

  12. #12
    Master huytonman's Avatar
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    Quote Originally Posted by Bodo View Post
    Few more detailed pictures here Keith that may help.

    http://forum.tz-uk.com/showthread.ph...ssion-Complete

    Also Martin's superb posts that helped me a tonne...

    https://adventuresinamateurwatchfett...ry/seiko/7548/
    Great stuff, much appreciated!

  13. #13
    Master
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    what a great piece of kit! Thanks for write up & photos

  14. #14
    Journeyman
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    Looks like a useful bit of kit Bodo, I don't have much quartz in the collection, but often the ones friends bring to get fixed are quartz, so this might make its way onto the 'want' list.

    Where is the trimmer? Ive not had to adjust one yet :-)

  15. #15
    Grand Master Daddelvirks's Avatar
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    Great post/kit/movement :)

    Nice to see this "workhorse" amongst the quartz movements in parts, of which quite a lot are metal to my amazement.
    Got a new watch, divers watch it is, had to drown the bastard to get it!

  16. #16
    Craftsman Bodo's Avatar
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    Quote Originally Posted by Seang View Post
    Looks like a useful bit of kit Bodo, I don't have much quartz in the collection, but often the ones friends bring to get fixed are quartz, so this might make its way onto the 'want' list.

    Where is the trimmer? Ive not had to adjust one yet :-)
    The little gold screw at 3 o'clock, just next to the battery strap screw. :)


    Anticlockwise -
    Clockwise +

  17. #17
    Master
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    Quote Originally Posted by Bodo View Post
    It wasn't cheap! Cousins have them, Paul. I don't want to think about the price too much. :)
    Youíll have shares in Cousins soon Guy

  18. #18
    Craftsman Bodo's Avatar
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    If I had a spare 5k..I'd be adding a lot to the basket.:)

  19. #19
    Thank you for posting your work. It's always interesting to see someone who knows what they're doing posting.
    It also belies the myth that quartz watches "have no soul."
    Great stuff!

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