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SW200 Ratchet Wheel Replacement

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  • SW200 Ratchet Wheel Replacement

    Some of you may know, some may not, when Sellita first introduced the SW200 automatic movement there some issues. One of the more common issues that people ran into was with the gear teeth shearing off on some of the wheels/gears. Both the design of the teeth and the strength of the metal used were causing the issues. With the introduction of the SW200-2, these issues were addressed and resolved.
    This is the issue with one of my older SW200 movements. Several teeth sheared off of the ratchet wheel, in two different locations on the gear.
    Without getting all crazy technical, I will try to give a brief explanation of the parts that are included in this repair.
    The ratchet wheel sits atop of the barrel, which in turn houses the mainspring. The mainspring stores the "energy" that is used to power the movement. The ratchet wheel is turned by two different sources in an automatic movement, the crown wheel and automatic winding module. The crown wheel receives its power from the crown when the movement is manually wound. The automatic winding module receives its power from the rotor/oscillating weight.
    So, when the watch is manually wound with the crown, the power/energy is transferred from the person winding the crown to the crown wheel to the ratchet wheel to the mainspring, where it is stored and ultimately released to run the movement. When the watch is wound, via the rotor, the power/energy is transferred from the person wearing/moving the watch to the rotor/oscillating weight to the ratchet wheel to the mainspring, where its is stored and released.
    With the sheared and broken teeth on the ratchet wheel, it was difficult and dangerous to manually wind the movement. I could feel the "slip" of the gears as the crown wheel made contact(or lack of contact) with the broken teeth.
    Finding parts for the SW200 is not very difficult, as most are interchangeable with the ETA 2824 and other "clone" movements.

    This is a fairly simple and straight forward repair. Fortunately, I was able to keep the movement in the case for this repair, as only a few parts needed to be removed and all of these parts are easily accessible through the case back. A few very important things to keep in mind...
    TAKE YOUR TIME, DO NOT RUSH YOURSELF.
    USE THE RIGHT TOOL FOR THE JOB. If your screwdriver is too big or too small parts can get damaged, let alone the frustration.
    USE PROPER LIGHTING. Do repairs in a well lit area, without carpeting. If a screw or other part drops onto the carpeting, you will NOT find it. Trust me

    1-Remove the case back.
    2-Inspect the movement for any foreign objects, like broken teeth from gear.
    3-Remove the rotor screw and set aside. You may need to brace the rotor depending to prevent it from moving while removing the screw. If you do, take caution not to damage anything.
    4-Carefully lift and remove the rotor. Keep the related parts together so you don't mix up screws or forget what goes where.
    5-The automatic winding module is now accessible. There are two, small blue screws on opposite ends of this plate. These two screws hold the plate/winding module in place. Remove these two screws and set aside.
    6-Carefully lift and remove the winding module/plate. You may need to GENTLY "pry" this loose.Again, GENTLY! There are gears attached to the underside of the plate that come into contact with the ratchet wheel, be cautious not to damage these gears or their teeth. Remember to keep the two screws, that hold this plate in place, with the plate and do not loose them.
    7- Now the ratchet wheel and crown wheel are exposed. If the movement is running, you need to release any power from the mainspring. To do this, there is a small lever mechanism next to the crown wheel. This lever allows the crown wheel to turned, winding the mainspring, and prevents the reverse turning of it with the small post that engages with its gears. Using the tip of your tweezers or a small screw driver, push on this lever while slowly turning the crown counter clockwise. By holding and turning the crown, it prevents the rapid and dangerous release of energy from the mainspring, which could damage or break it. Once all of the energy is released and movement stops running, you can remove the ratchet wheel.
    8-Unscrew the ratchet wheel screw and remove it. The wheel can now be removed. Be careful when doing this, it is in contact with the crown wheel and the gear teeth should be interlocked. Again, you may need to GENTLY pry the wheel up. Remove the damaged wheel and set aside.
    Time to reassemble the movement.
    9-Insert the new ratchet wheel carefully. Before attaching the screw, slightly turn the crown to ensure that the teeth of the ratchet wheel and crown wheel are engaged properly. Secure the ratchet wheel screw, being sure not to over tighten it.
    10-Reattach the automatic winding module plate. Again, patience and precision. Align the plate, screw holes and gears, but DO NOT press down on the plate yet. The gears need to be in place and interlock with before securing the plate. As above, slightly turn the crown to allow the gears to line up and interlock properly. The plate should "fall" into place when everything is correctly in seated.
    11-Secure the two blue screws that hold the automatic winding module in place. Do not over tighten. These screws are very very small and the threads can be easily stripped.
    12-Before attaching the rotor, check the alignment and ensure that everything is working properly by manually winding the crown a few times. If there is no resistance, (other than normal), the mainspring is being wound, and the movement is running, than everything was assembled correctly.
    13-Place the rotor on the automatic winding plate and align the screw hole. Attach and secure the screw.
    14-Again, check and ensure proper winding and functions of the watch/movement.
    15-Reinstall the case back.

    Bam! A new ratchet wheel installed and a perfectly functioning timepiece again.....

    All of the removed parts could and should be cleaned and lubricated prior to reinstalling them. As well, the gasket should be inspected and lubricated if need be.

    Thank you for reading this long and boring post...

  • #2
    SW200 Ratchet Wheel Replacement



    Here you can see the damaged ratchet wheel

    And the new wheel to be installed






    The automatic winding module/plate and rotor after being removed





    SW200 with automatic winding mechanism removed and ratchet wheel exposed




    Damaged ratchet wheel removed. You can see where the teeth are missing, around 12 o'clock and 4 o'clock

    Comment


    • #3
      SW2)) Ratchet Wheel Replacement

      First things first great job. I have a grand diver with a sw2)) and could feel the crown not winding the watch and called invicta and they told me I didn't need to wind the watch just shake it. I started laughing at him and demanded they fix it which they did. I never knew they had a wide spread issue with the movement. Thanks for sharing

      Comment


      • #4
        SW2)) Ratchet Wheel Replacement

        Great DIYer if one can... You are a brave man, my hands are too shaky for this kind of work.;)
        Everybody's Got Something To Hide Except Me And My Monkey...

        Comment


        • #5
          SW2)) Ratchet Wheel Replacement

          Great work and info!

          Thanks for taking the time to post it.

          Comment


          • #6
            SW2)) Ratchet Wheel Replacement

            Thanks guys. I think it took long to type the instructions than it did to actually do the repair. You know, its only 4 screws that need to be removed.

            Comment


            • #7
              SW2)) Ratchet Wheel Replacement

              Excellent post. I've feared getting an original SW2)) because of this very issue but so far have only accumulated the -). Should I ever come across a movement with this issue, having your post in mind will surely help.[br]Thanks again.

              Comment


              • #8
                SW2)) Ratchet Wheel Replacement

                That's advanced. Good job!!!

                Comment


                • #9
                  SW2)) Ratchet Wheel Replacement

                  Wow, you are the man. Great post and toast.[img src=http://www.pic4ever.com/images/)28fs3)8)8).gif]

                  Comment


                  • #10
                    SW2)) Ratchet Wheel Replacement

                    Thanks for the lesson, nice job.
                    Hazy....try again...

                    Comment


                    • #11
                      SW2)) Ratchet Wheel Replacement

                      Great write-up and photos! Thanks for sharing that with us.
                      Android to Aragon - Wing's the thing.

                      Comment


                      • #12
                        SW2)) Ratchet Wheel Replacement

                        Another DIY success story. Thanks for sharing!

                        Comment


                        • #13
                          SW2)) Ratchet Wheel Replacement

                          Great Post thanks for sharing!

                          Comment


                          • #14
                            SW2)) Ratchet Wheel Replacement

                            Thank you for posting this cool DIY, and congrats[br]on a job well done.

                            Comment


                            • #15
                              SW2)) Ratchet Wheel Replacement

                              I actually need this for an Invicta I have. Thanks, I have been wondering what to do about it, now I can experiment.
                              Stop looking at the world through rose colored bifocals.

                              Comment

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