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      SeiyaJapan blog

      A way to rebirth of Seiko’s mechanical watches Vol.2/ 4S movement

      A way to rebirth of Seiko’s mechanical watches Vol.2/ 4S movement

      Summarized and translated the article, “A way to rebirth of Seiko’s mechanical watches”
      (p.5-9, GS9 "Grand Seiko Magazine / Grand Seiko Nine" TWO, March 2015) 

      Production of the new 4S caliber

      Seiko formed an in-house mechanical watch project team due to the
      positive response received from the 6810 UTD series.
      But no engineer with experience in mechanical caliber design was
      available in a company.

      So, the new caliber, 4S35 was decided to manufacture based on the old
      52 caliber, which was produced 20 years ago.
      The 52 caliber prided itself on precision of the 1970’s Chronometer standard.

      At last, 200,000 4S calibers were produced. Seiko understood it was
      too many. However, manufacturing new caliber costs a lot. Seiko had to
      make 200, 000 calibers.

      The first watch fitted with the 4S was on sale at the end of 1992.
      It was SCVK001 (4S35-8000) with 4S35 caliber.

      Mechanical watches became the focus of attention in the media.
      This boosted Grand Seiko’s mechanical type revival.

      Tanaka wanted to create new Grand Seiko with new high-end caliber. But
      because there were too many 4S caliber surplus, company didn't want to
      develop new caliber.

      As Seiko had to keep to use 4S calibers, they made mechanical watches
      like "Credor Chronometers GBAY992”,  "KING SEIKO 2000 repro model", Laurel, and SUS with 4S calibers.

      Grand Seiko’s mechanical type revival

      Some years later, Seiko began to produce new Grand Seiko with new
      mechanical caliber. It was 1996.

      A young engineer, Jujo Kouichiro tried to fine-tune 4S calibers for new Grand
      Seiko first. But he soon understood it was impossible. Because Grand
      Seiko needs more precision accuracy.

      Each and every retired technical expert was interviewed in order to
      form the new movement.
      Many test products were developed by utilizing 3D CAD computer
      technology. The precision and structure of the test products were
      redone over and over again by ”Ohira Akira”, allowing the completely new movement to be
      completed in just 2 short years.
      (Please search ”Ohira Akira” by Google) 

      The Grand Seiko SBGR001 mechanical type was revived on November 27, 1998.


      Citizen watch instructions are available online only


      I have an announcement to make.

      Citizen has ceased to provide instructions for their wristwatch lineup.

      Their instructions have been made available online.

      They are available in English, French, Spanish, German, Italian, Portuguese, and Chinese.

      They can be printed,  but it will use up a lot of paper, so please print only the necessary pages.



      About the OCW-T200 series Mobile Link "Oceanus Connected"

      The OCW-T200 easily connects to your smartphone via Bluetooth where you can check the information available on Oceanus.


      Top screen


      History of Self Adjustment

      You can view its history of self adjustment records to view time zone corrections via radio waves and Bluetooth.



       Solar Power Charging Transition

      The amount of energy generated by the solar cell of the watch is displayed.


      Latest Updates

      It updates with the latest time zone and summer time information from each country.

      Phone finder 

      It searches for your smartphone.