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seiko_4s15

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seiko_4s15 [03.12.2022 14:06] (current) gerdlothar
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 +====== Seiko 4S15 ======
 +**4S15** is one of a family of high-end [[automatic]] watch movements from [[Seiko]]. Other closely-related members of this **4S** family include the **4S12**, **4S24**, **4S25**, **4S27**, **4S28**, **4S35**, **4S36**, **4S71**, **4S76**, **4S77**, and **4S79**.
 +
 +===== Overview =====
 +The **4S** family was introduced in [[1992]] with the **4S35** as a higher-end automatic alternative to the mainstream [[Seiko 7002|700x]] and [[Seiko 7S26|7S]] families. The line is based on the [[King Seiko]] [[Seiko 5206|5200]] series from the 1970's. Unlike most other [[Seiko]] movements, the 4S family operates at 28,800 vph and includes both [[automatic]] and [[hand winding]] variants.
 +
 +The 4S15 was a high-end movement, adjusted to +15/-10 seconds per day from the factory. This is nearly as accurate as the "Top" grade [[ETA 2892]] and similar movements. It features a thermo-compensating balance and hairspring, and the movement [[hacking|hacks]] and can be [[hand-winding|wound by hand]]. Cal. 4S15 was only used in two watches The Seiko SCVK001 and SCVK002, both targeted at the European market. A nearly-identical movement, Cal. **4S71**, was used in [[Credor]] watches and is gold plated. A less-adjusted movement, the **4S15**, appeared later and is the most common of the family.
 +
 +Once Seiko introduced the [[Seiko 6R15|6R family]], the 4S was moved upmarket and the simple movements were discontinued. The series was refreshed in [[1995]] with the addition of the more-complicated **4S71** and derivatives. These remove the date window and add subdials and complications such as [[small seconds]], [[retrograde day]], date and [[24 hour]] subdials, and [[power reserve indicator]]s. Since [[2007]], the 4S series has been limited to Seiko's Credor range.
 +
 +This family of movements powered Seiko's line of [[GMT]] and [[dual timezone]] watches, inheriting that task from the [[Seiko 6200|6200]] and [[Seiko 6100|6100]] series of the 1960's and the [[Seiko 5600|5600 series]] of the 1970's and lasting from the mid-1990's through 2013.
 +
 +The Calibre 4S family is assembled at Seiko's [[Shizukuishi Watch Studio]] in Morioka, Iwate prefecture, Japan, along with other high-end Seiko movements.
 +
 +===== Variants =====
 +The 4S family operates at 28,800 A/h, an unusually [[high beat]] rate for Seiko.
 +
 +There are essentially three "generations" of 4S movements 
 +
 +  - The **4S15** and derivatives (4S12, 4S15, 4S24, 4S25, 4S28, and 4S35) are simpler movements with few complications directly derived from the [[Seiko 5206|5200]] line. They were used for mid-range watches while Seiko developed the less-expensive [[Seiko 6R15|6R]] family of movements.
 +  - The family moved upmarket with the **4S71** and derivatives (4S77, 4S79, and 4S79A). These add complications to compete with higher-end Swiss watches and powered the first Brightz and Credor automatics. The ultimate 4S movement was the hand-crafted 4S79 used in the limited-edition Credor GBAY992 and GZAY999 (limited to 500 and 20, respectively), with a weight attached on the [[hairspring]] like the [[King Seiko 44KS]] for chronometer accuracy.
 +  - The final family members were complicated movements exclusively used in Brightz and Credor watches, including the 4S27/4S77 and 4S36/4S76.
 +
 +Special note: The 4S15, 4S25, and 4S35 are all essentially the same movement. The 4S15 is the base model, with the 4S25 being essentially identical on paper. The 4S35 is adjusted to +15/-10 seconds per day, while the others are certified to +25/-10.
 +
 +^Movement ^Date ^Winding ^Hands ^Date ^Subdial ^Jewels ^Power Reserve ^
 +|4S12 |1997-1998 |Automatic |Hours, minutes, seconds, [[24 hour]] [[GMT]] |Date |None |25 | |
 +|4S35, 4S25, 4S15 |1992-1997, 2000 |:::|Hours, minutes, seconds |:::|:::|:::| |
 +|4S24 | |Manual |Hours, minutes, seconds |None |:::|21 | |
 +|4S28 | |:::|Hours, minutes |:::|[[Small seconds]]|24 | |
 +|4S71 |1995 |Automatic |Hours, minutes, seconds |None |None |25 |40 Hours |
 +|4S77, 4S27 |1996-2006 |:::|:::|Subdial |Date, [[retrograde]] day, [[24 hour]] [[GMT]] |28 |50 Hours |
 +|4S76, 4S36 |2004-2013 |:::|:::|:::|Date, [[retrograde]] day, [[24 hour]] [[GMT]], [[power reserve indicator]] |31 |:::|
 +|4S79, 4S29 | |:::|Hours, minutes |None |[[Small seconds]], [[power reserve indicator]] |:::|40 Hours |
 +|4S79A | |Manual |:::|:::|:::|31 | |
 +
 +
 +===== Applications =====
 +  * 4S12
 +    * Seiko SCFF, SUS GMT
 +  * 4S15
 +    * Brightz (SAGN), Laurel (LHAM), Alpinist (SCVF), Titanium Diver, SUS Military, King Seiko LE (SCVN001)
 +  * 4S24
 +    * Seiko (SCVG), Laurel LJAL
 +  * 4S25
 +    * Seiko (SCVJ)
 +  * 4S27
 +    * Brightz (SAGN)
 +  * 4S28
 +    * Brightz (SAGN)
 +  * 4S29
 +    * Laurel (LJAR), Brightz (SAGN)
 +  * 4S35
 +    * Seiko SCVK001/2
 +  * 4S36
 +    * GMT Retrograde (SAEN, SARN)
 +  * 4S71
 +    * Credor
 +  * 4S76
 +    * Credor Node (GBBT, GCBT)
 +  * 4S77
 +    * Credor Retrograde GMT (GCBG)
 +  * 4S79
 +    * Credor (GBAY, GCAY, GZAY)
 +
 +===== External links =====
 +  * [[http://people.timezone.com/library/cjrml/cjrml0024|Four Hundred Years After, Part II, The Legacy of Seikosha]]
 +  * [[http://www.timekeeper.co.nz/viewtopic.php?f=20&t=763|Qualified for Time Travel: SEIKO 4S36 GMT Retrograde SARN001]]
 +  * [[http://fnord.phfactor.net/2008/03/20/where-my-watch-came-from/|Where My Watch Came From]]
 +  * [[http://www.watchprosite.com/show-forumpost/fi-657/pi-5568098/ti-824423/t--interview-akira-ohira-watchmaking-father-of-modern-mechanical-grand-seiko/|Interview: Akira Ohira - watchmaking "Father" of modern mechanical Grand Seiko]]
 +  * [[https://musingsofawatchaddict.wordpress.com/2015/02/02/the-enigmatic-seiko-4s-movement-continued/|The enigmatic Seiko 4S movement ...continued]]
 +  * [[http://www.seiko-watch.co.jp/resource/pdf/manual/4S15.PDF|Seiko 4S15 Manual]]
 +  * [[http://www.seiko-watch.co.jp/resource/pdf/manual/4S27.PDF|Seiko 4S27 Manual]]
 +  * [[http://www.seiko-watch.co.jp/resource/pdf/manual/4S36.PDF|Seiko 4S36 Manual]]
 +  * [[http://www.seiko-watch.co.jp/resource/pdf/manual/BGMCE.pdf|Seiko Credor 4S71, 4S76, 4S77, 4S79 Manual]]
 +  * [[https://musingsofawatchaddict.wordpress.com/2016/09/05/seiko-scvk001-the-start-of-the-seiko-4s-family/|Seiko SCVK001 - The start of the Seiko 4S family...]]
 +
 +
 +<WRAP ud ud_mov>
 +
 +**Description:**
 +  * [[Automatic]] or [[manual winding]] movement
 +
 +**Functions:**
 +  * Hours, minutes
 +  * [[Central seconds]] or [[small seconds]]
 +  * Rapid calendar advance
 +  * [[Automatic]] [[bidirectional]] winding
 +  * [[Diashock]]
 +  * [[24 hour]] [[GMT]] subdial
 +  * [[Power reserve indicator]]
 +  * [[Retrograde]] day
 +  * Date wheel
 +
 +**Data:**
 +  * 21, 25, 28, 29, or 31 [[jewels]]
 +  * 28,800 A/h
 +
 +**Production period:**
 +  * Since [[1992]]
 +</WRAP>
 +
 +{{tag>Movements GMT_movements Automatic_movements Manual_winding_movements Seiko_calibres}}
  

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