====== 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...]] **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]] {{tag>Movements GMT_movements Automatic_movements Manual_winding_movements Seiko_calibres}}