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On My Bench - Seiko 7548-700B

  1. JimInOz Melbourne Australia Feb 26, 2020

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    While waiting for parts for another watch, I decided to get to work on another one that had turned up.

    The owner wanted new seals and battery and asked me to see if I could fix a problem with the setting mechanism.

    It's a nice Seiko quartz diver, you can see the state of the crystal, and the dial underneath is in excellent condition, although it's hard to tell in this shot.

    Front.JPG

    Caseback is in good condition, doesn't look like anybody has used scissors or circlip piers to open it.

    Back.JPG

    First thing is to open it.

    CasebackOff.JPG

    Movement looks OK, no signs of water entry or battery leakage.

    Movement.JPG
     
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  2. JimInOz Melbourne Australia Feb 26, 2020

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    Disassembly.

    Movement is taken out and the hands removed to be stored for safekeeping along with the movement (in seperate containers).

    HandsOff.JPG

    Then we can pop the bezel off. Eeew....cruddy.

    BezelOff.JPG

    Glass ring and glass/gasket and dial ring all removed and ready for cleaning.
    (Pictures are not just for your enjoyment, they're a reference so I put everything back in the right order, not an issue here, but some assemblies are a bit more complex).

    GlassOut.JPG
     
  3. zinengineer Feb 26, 2020

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    I find myself “following “ all of these
     
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  4. JimInOz Melbourne Australia Feb 26, 2020

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    After some brushing and ultrasonic cleaning (not the dial ring though!), the case parts are ready to be put back together.

    CaseCleaned.JPG

    The dial ring is fitted, then the gasket ring and gasket, then the glass is pressed in.

    GlassPressed.JPG

    The glass bezel is pressed on and then we're ready for the rotating bezel to go on after the gasket is lubricated and fitted.

    ReadyForBezel.JPG
     
  5. JimInOz Melbourne Australia Feb 26, 2020

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    The crown stem assembly is next, it was pretty dirty and I only took a pic of the grease in the crown :eek:.

    StemGunk.jpg

    The crown/stem is in two parts so the spring and washer have to be pushed in so the stem can be removed and then we can access the crown seal and pull it out.

    CrownSealOut.jpg

    Now we can fit a new crown seal (after lubricating with silicone grease). All done.

    NewCrownSeal.jpg

    A fixture is needed to hold the crown and re-fit the stem. I used my lathe chuck mounted to a wood block.

    StemFitted.JPG
     
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  6. JimInOz Melbourne Australia Feb 26, 2020

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    With the case assembled and the freshly restored crown/stem fitted it was time for a pressure test, So off to the kitchen. The watch case is placed in water in a vacuum container, a good vacuum pumped out (as much as I could manage) and the case checked for bubbles.

    Success! No bubbles!

    VacTest.JPG

    The vacuum is released and the watch sits in the water for about five minutes to allow atmospheric pressure to force water into the case.
    It's too cold outside today to sit the watch in the sun to warm it, so the case is warmed to 45ºC in one of my drying units (an incandescent 10W pilot globe and some old bean cans).

    Warming.JPG

    Out of the warmer and a drop of ice cold water is put onto the crystal and left for 10 seconds and quickly wiped away. If a condensation spot is seen under the crystal it means that water has penetrated.
    In this case, success! No condensation! ::psy::

    IceTest.JPG

    Part one finished, I can investigate the issue with the movement and service it as well.
     
  7. Jeeper Feb 27, 2020

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    Absolutely brilliant.

    Thanks for posting. I am waiting for the other one to finish.

    What sort of time does it take you to service a 3 hand automatic, I would be interested to know.

    Thanks

    Jeeper
     
  8. JimInOz Melbourne Australia Feb 27, 2020

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    Actual time?

    About 4 to 6 hours, depending on problems or glitches.

    However, total time can get pushed out due to other interruptions, e.g.: life, gardening, shopping, searching for parts, waiting for parts, many other little things that get in the way.

    The last one (on a Tudor 390.......shudder) took about three months from receipt to return in real time.
     
  9. Jeeper Feb 27, 2020

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    Thanks, JiminOZ, nice bit of business for Omega in UK £450 GBP for a service on PO with 2500

    Jeeper
     
  10. wsfarrell Feb 27, 2020

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    Beer?
     
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  11. JimInOz Melbourne Australia Feb 27, 2020

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    The movement has now been stripped and is ready for cleaning.

    All the parts laid out.

    StrippedForClean.JPG

    I had an idea of what was causing the setting problem so I checked the setting components, and sure enough here is the problem.

    ClutchWheelRemoved.jpg

    The clutch wheel has been severely worn down. After all the parts were cleaned I had another look and compared it to a clutch wheel from a different Seiko. A view from the top.

    ClutchWheelUpper.png

    You can see how badly it's worn, the difference is obvious when looking at them together from the side.

    ClutchWheelSide.png

    So how does this happen? Possibly a design fault, or incorrect assembly at some time.

    I found out that others have had similar issues with this movement, see this example where Martin had a problem with the setting mechanism. Although slightly different, it points to a latent defect with this setup (IMO).

    Here's an explanatory pic I borrowed from Martin's blog. It shows a small pillar (my pointers in blue) on the end of the setting wheel lever, this is held down by the date wheel plate so it is meant to stop the setting wheel lever from riding up when the clutch wheel is engaged and turning, but there is too much clearance between the top of the pillar and the date wheel plate. This allows the assembly to lift, thereby partially disengaging the clutch wheel and causing wear. As the wear increases, the twisting force of the worn teeth cause the clutch lever to jump over the teeth of the setting wheel.

    7548-minute-wheel-bridge.jpg

    Solution?

    A new Clutch Wheel (the setting wheel is OK). I'll have a look through my parts as this one is used in a large number of Seiko movements.

    If I don't have one, the search will begin. But I'm getting used to that :D.
     
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  12. JimInOz Melbourne Australia Feb 28, 2020

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    Oh how I love the variations on eBay :rolleyes:.

    Screen Shot 2020-02-28 at 4.58.56 PM.png
     
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  13. jaguar11 Feb 28, 2020

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    Great read!!!!!
     
  14. verithingeoff Feb 28, 2020

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    :D
     
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  15. S.H. Feb 28, 2020

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    Still working with what looks like a ding in the coil? Lucky!
     
  16. JimInOz Melbourne Australia Feb 28, 2020

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    Yeah, worried me when I saw it but luckily it was hit with a "blunt object" I suspect, no wires cut or broken. There's another small ding just to the left of centre, and again, no breaks.
     
  17. JimInOz Melbourne Australia Apr 1, 2020

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    Long time no update.

    The good news. ::psy::
    The owner sourced a new setting lever assy and clutch wheel from Cousins in the UK, and after a voyage slightly shorter then the First Fleet they arrived.

    The Bad News. :mad:
    He ordered a setting lever for a Seiko 6309, not a 7548. :whipped:

    The Good News, Evening Edition. :cool:
    It appears that the setting lever assy, like many other parts, are based on the 6309, so although it has a slightly different part number, it is identical in form, fit and function.

    So where are we?

    The new parts were inspected then test fitted, then removed, lubricated, installed and checked with the complete watch in running/adjusting modes.

    Everything is now working like new and the watch is undergoing a timing check for the next few days.
    Sorry, no pics at the moment, been too busy with other projects but I'll post a shot tomorrow if anybody wants to see the completed project.

    ;)

    Cheers

    Jim
     
  18. tomkenmag Apr 1, 2020

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    Awesome post, love these step-by-steps with pictures.
     
  19. JimInOz Melbourne Australia Apr 1, 2020

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    As a final action on this one, a picture.

    Vange_7548_Fin.JPG
     
  20. SuperJazz Oct 27, 2020

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    Hi - great job!

    I have just refurbished mine, using your tips and photos. A first for me; I have attached a photo. I've replaced the Hardlex crystal with sapphire, put in a new bezel insert, replaced the hands (they were beginning to rust up), crown and stem (this was a challenge, as they came in pieces) and relumed the indices.

    As a longtime diver and instructor I bought the watch in 1978 in Cyprus to do my first diving expedition there, and it has undertaken over 1200 dives. So despite owning Seamasters, other brands (and other Seikos) over the years, I'd always wanted to get it back to 'fitness'.

    I don't know if you can help me with a small problem? The bezel was missing it's ballbearing when I removed it, which explained the absence of 'ratchet' capability for a few years. I replaced the spring and ballbearing during refurbishment, having obtained them from an online vendor. The ratchet now works, but the bezel is almost impossible to turn - it is very stiff indeed. I have removed it several times and cannot see any damage or obstructions. I've replaced the gasket. If I leave the ballbearing out it turns freely, but of course doesn't click as it should. I'd like to sort it if I can. Do you have any suggestions?

    Thanks in advance for your help.

    Best regards

    Steve Qi9OG4vsRZ6lMZvOhtVW7w.jpg