====== Seiko 6S78 ======

{{wst>author|[[Foskett, Stephen|Stephen Foskett]] ([[https://grail-watch.com/|Grail Watch]])}}

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== Picture links ==
  * [[https://i847.photobucket.com/albums/ab33/nikidasi/6S37/SEIKO%20FLIGHTMASTER%206S37-0010%200D0254/IMG86686.jpg|Picture of the calibre Seiko 6S37A]]
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**6S78** is one of a family of [[column wheel]] [[chronograph]] movements from [[Seiko]]. Other closely-related members of this **6S** family include the **6S74**, **6S77**, **6S99**, and **6S37**

===== Overview =====
The **6S** family was introduced in [[1998]] to power Seiko's 3-register [[Credor]] "Phoenix" [[chronograph]]s. The project was a major development for Seiko, with the company calling in watchmakers from retirement to develop a truly modern and advanced movement. The resulting 6S78 was critical in showing that Seiko could compete in the resurgent high-end mechanical watch market. The "Phoenix" chronograph series were marketed exclusively in Japan and were embraced for this reason.

The first calibre was the [[automatic]] 34 jewel 6S78, and this is the basis for this family. The 6S78 was used for the Credor Phoenix Chronograph, model GCBP, from 1999 through 2004.

In [[2001]], Seiko also released a special high-end Prospex Flightmaster, model SBDS001, with Cal. 6S37 which added a power reserve indicator at 2 30 on the dial. This remained in production through 2011. Cal. 6S37 was also used in the Brightz Phoenix Chronograph, model SAGH, and Credor Signo chronograph, model GCBK, from [[2010]] through [[2016]]. The Credor version of this movement was Cal. 6S77, which was used in the Credor Pacifique chronograph, model GCBK, from [[2003]] through [[2005]].

The high-end Credor mechanical chronograph, model GBBL993, was introduced in [[2002]] and produced through [[2005]]. It used Cal. 6S99, a gold-plated skeletonized version. The [[hand winding]] 35 jewel 6S74 variant adds a [[power reserve indicator]], and is identical to the skeletonized 6S99.

In [[2005]], Seiko introduced Cal. 6S28, which was essentially similar to the original 6S78. It was used in the Brightz chronograph, model SAGP, through [[2007]] before moving to the Brightz Phoenix chronograph, model SAGH, from [[2008]] through [[2013]]. In [[2012]], Cal. 6S28 was redeployed for the Ananta brand in the limited-edition Automatic Chronograph, model SSD001, and SAEH line. These were out of production in just a few years.

A final variant is the automatic 6S96 which is similar to the 6S77 but lacks the date window and 2 jewels but thus gains an additional 10 hours of power reserve.

The Calibre 6S family is assembled at Seiko's [[Shizukuishi Watch Studio]] in Morioka, Iwate prefecture, Japan, along with other high-end Seiko movements. Although the lower initial number (6) might indicate otherwise, the 6S chronograph is generally considered a higher-end movement than the [[Seiko 8R|8R family]]. This despite the fact that the newer 8R has a [[vertical clutch]] rather than the [[oscillating pinion]] of the 6S.

===== Variants =====
The [[TAG Heuer Calibre 1887]] is a derivative of the Seiko 6S37.

^Movement ^Winding ^Hands ^Date ^Subdial ^Jewels ^Decoration ^Power Reserve ^
|6S78, 6S28 |Automatic |Hour, minute, chrono seconds |Date |[[Chronograph]], small seconds |34 |Brushed plates, [[colimaconnage]] rotor, gold plated |50 Hours |
|6S77 |:::|:::|:::|Chron0graph, small seconds, [[power_reserve_indicator|power reserve indicator]] |40 |:::|:::|
|6S37 |:::|:::|:::|:::|:::|Brushed plates, colimaconnage rotor, [[rhodium plated]] |:::|
|6S96 |:::|:::|None |:::|38 | |60 Hours |
|6S74 |Manual |:::|:::|:::|35 |Tokyo stripes, gold plated |:::|
|6S99 |:::|:::|:::|:::|:::|Tokyo stripes, gold plated, [[skeletonized]] |:::|

===== Applications =====
  * 6S28
    * Ananta (SAEH, SSD), Brightz Phoenix (SAGH)
  * 6S37
    * Credor Signo (GCBK), Prospex Flightmaster (SBDS), Brightz Phoenix (SAGH)
  * 6S77
    * Credor Signo and Pacifique (GCBK)
  * 6S77
    * Credor Phoenix (GCBP)
  * 6S99
    * Credor (GBBL)

===== External links =====
  * [[http://people.timezone.com/library/cjrml/cjrml0024|Four Hundred Years After, Part II, The Legacy of Seikosha]]
  * [[http://fnord.phfactor.net/2008/03/20/where-my-watch-came-from/|Where My Watch Came From]]
  * [[http://www.seiko-watch.co.jp/resource/pdf/manual/BSB6SCAN.pdf|Seiko 6S28, 6S37 Manual]]
  * [[http://www.seiko-watch.co.jp/resource/pdf/manual/BGMCE.pdf|Seiko Credor 6S37, 6S74, 6S77, 6S78, 6S96, 6S99 Manual]]
  * [[https://reference.grail-watch.com/family/seiko-6s/|Seiko 6S Family Reference]]


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**Description:**
  * [[Automatic]] or [[manual winding]] movement
  * [[Column-wheel]] [[Chronograph]]

**Functions:**
  * Hours, minutes, seconds
  * [[Automatic]] [[bidirectional]] winding
  * [[Diashock]]
  * Chrono function [[central seconds]], 30-minutes, 12-hours
  * [[Power reserve indicator]]
  * Date wheel

**Data:**
  * 28.4 mm, H 7.2 mm
  * 34, 35, or 40 [[jewels]]
  * 28,800 A/h
  * [[Power reserve]] ca. 50h

**Production period:**
  * Since [[1998]]
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{{tag>Movements Chronograph_movements Automatic_movements Automatic_chronograph_movements Manual_winding_movements Seiko_calibres Column_wheel_chronograph_movements}}