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On My Bench - Seiko 7548-700B - Another one!

  1. JimInOz Melbourne Australia Feb 3, 2021

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    I serviced a Pepsi variant of one of these a while ago.

    This one is the plain black bezel version. It's been well used, but not abused. Although the crystal has seen some welding I suspect.

    Dial.JPG

    Caseback is nice and clean and no evidence of Edward Scissorhands doing any tinkering.

    Caseback.JPG

    After the usual check and a brush down to remove crud, the caseback was removed and the battery taken out.

    BatteryOut.JPG

    Then the hands could be aligned and removed.

    HandsOff.JPG

    With the hands off and safely stored the dial is removed, exposing the day/date wheels which come off next.

    DayDate.JPG

    Beneath the day/date wheels are all of the dial side parts which are removed without and problems noted.

    DialSide.JPG

    With all the bits put away, it's flip the movement over to do the working side. Here I've removed the train bridge, exposing the step rotor and the wheels.

    Train.JPG

    The step rotor has been removed and captured in its own plastic container (it's a very powerful mini-magnet!). Similarly, the circuit assembly and coil block are removed and put into safe containers.

    CoilCircuit.JPG

    With the last of the movement parts out and safely stowed, it's time for the case. No dramas and everything is now ready for cleaning.

    CaseParts.JPG

    And does it need some cleaning!

    Grunge.JPG

    More to come.
     
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  2. JimInOz Melbourne Australia Feb 3, 2021

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    The case wasn't the only cruddy item.

    Bezel ring ::puke::

    Crud2.JPG

    But after some elbow grease and some ultrasonic agitation, I think it turned out quite well.

    BezelRing.gif

    As did the case with the same scrub-a-dub-dub and bzzzzzzzzzzzzzzzzzzzzzzzzzzz.

    IMG_5354.JPG
     
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  3. JimInOz Melbourne Australia Feb 4, 2021

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    Last little bits for today.

    With all the case parts cleaned and checked, it was time to drop in the chapter ring, seal ring, crystal seal and press in a new crystal.

    NewCrystal.JPG

    Then the bezel ring was pressed on.

    BezelRingOn.JPG

    That's it for today. I'll take this grungy bezel and let it soak in a weak solution of water/dish liquid overnight and use a soft brush and pegwood to clean it up tomorrow.

    UnderBezel.JPG

    And now I think it's time for a beer before dinner.
     
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  4. JimInOz Melbourne Australia Feb 13, 2021

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    Well, nothing for ten days!
    :whipped:

    Been a bit busy though, getting a car ready to transport interstate for my Grandson's birthday present.
    I wasn't totally slack though. The bezel was let to soak and then cleaned with pegwood and a soft toothprush, then it received its new seal (properly lubricated) and the bezel was pressed on.

    IMG_5360.JPG

    Last step for the case was to clean/inspect/lubricate/install the crown/stem assembly. I'm glad I had my little crown tool to help with that.

    CrownSeal.JPG

    The case was then completed by fitting a new caseback seal to the case so it would be ready for a basic waterproof test.

    CaseCompleted.JPG
     
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  5. JimInOz Melbourne Australia Feb 13, 2021

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    With the case out of the way, I had time to turn my attention to the movement parts.

    MovementParts.JPG

    The main plate/wheels/setting parts etc were "ultrasoniced". Parts unsuitable for wet cleaning were done with fresh Rodico Premium.

    The circuit board was inspected and cleaned, again using fresh Rodico Premium. The circuit board was returned to its light proof container and I cleaned and inspected the coil.

    CoilCheck.JPG
     
  6. LuckyLes Feb 13, 2021

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    Question from the unitiated, why does the circuit board need to be protected from the light?
     
  7. vibe Feb 13, 2021

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    Who makes that press? It looks very nice.
     
  8. JimInOz Melbourne Australia Feb 14, 2021

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    It's just something I noted some time ago when servicing a Seiko Chrono with a caliber 7A28A.

    Screen Shot 2021-02-14 at 18.11.22.png



    I don't know if it's essential to protect the CMOS chip all the time, but it doesn't hurt to do it.
     
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  9. JimInOz Melbourne Australia Feb 14, 2021

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    I guess some company in China. I bought it a few years ago to replace a cheaper version and as yet I haven't had the need to upgrade.

    Just Google "watch crystal screw press".
     
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  10. omegaswisst Feb 14, 2021

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    Out of interest Jim do you press the crystal straight in or do you press a little then rotate the case then press again?
     
  11. jaguar11 Feb 14, 2021

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    Nice read Jim as usual. Looking forward to updates.
     
  12. JimInOz Melbourne Australia Feb 14, 2021

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    First press is light to check that the crystal has seated evenly in the gasket, then it's centred/set up level again and pressed in. I do rotate 90º for a final press, but don't know if it's needed or a recommended procedure.
     
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  13. vitriol Feb 14, 2021

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    That's cool:thumbsup:. I have read about those rings in the old school bezel assembly systems but never had any in my hands.
    I assumed that 7548' ring is the same as 630* ring, but no - 630* rings have L-shaped cross-section while yours is flat.
    .
    technical-drawing.jpg

    So, what does that ring do? Is it still engaged in fixing the crystal?
     
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  14. JimInOz Melbourne Australia Feb 14, 2021

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    Well I called it a bezel ring.
    As per your diagram (which I should have used as a reference) it is actually a "Glass Fixing Ring" and it does have an L-shaped cross-section.
     
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  15. JimInOz Melbourne Australia Feb 14, 2021

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    Re-assembly of the movement starts with the crown/stem being lubricated and installed, then the setting parts are fitted to hold the stem in place.

    IMG_5436.JPG

    Then we start the installation with the battery terminal and centre wheel and centre wheel bridge.

    IMG_5437.JPG

    Followed by the rotor stator, reset lever, step rotor and the remainder of the train.

    IMG_5438.JPG

    The coil and circuit block get fitted, the old battery is fitted for a check to see that all is working correctly.

    IMG_5439.JPG

    Back to the other side and the day/date parts are put on and checked. And that's enough for today.

    IMG_5440.JPG
     
  16. JimInOz Melbourne Australia Feb 14, 2021

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    One of the checks required after assembly of the wheel train is to confirm correct operation of the "hacking" mechanism.

    Screen Shot 2021-02-15 at 13.44.34.png
    And here it is in operation.

    SSLOP.gif
     
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  17. JimInOz Melbourne Australia Feb 14, 2021

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    Argh! I'm hopeless.

    I get so involved with the task at hand I forget to take photos.
    After the dial and hands were fitted it was cased up, given a new battery and will run for a while on my bench so I can keep an eye on it for any problems.

    So, all done.

    IMG_5444.JPG

    I think it turned out quite well.

    IMG_5445.JPG
     
  18. JimInOz Melbourne Australia Feb 14, 2021

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    PS: In closing, didn't anyone notice that it's not actually a 7548-700B as I titled this thread.

    The observant among you should have twigged that it's actually a 7548-7000!

    ;)

    Back.JPG
     
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  19. b-lilja Feb 14, 2021

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    Terrific!
     
  20. DaveK Yoda of Yodelers Feb 15, 2021

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    Cool graphics Jim :cool: