Seiko 4S77

	Brand:	Credor, Seiko
	Family:	Seiko 4S Family
	Height:
	Jewels:	28
	Reserve:	50 hours
	Frequency:	28,800 A/h
	Winding:	Automatic, Bi-Directional Automatic Winding
	Diameter:
	Complications:	24 Hour Hand, Date, Date by Pointer, Day, GMT Hand, Hacking Seconds, Hand Winding, Independently-Adjustable 12 Hour Hand, Quick Date Correction, Quick Day Correction, Retrograde Day
	Hands:	24 Hour Hand at 9:00, Central Hour Hand, Central Minute Hand, Central Seconds Hand, Date Pointer at 6:00, Retrograde Day Pointer at 2:30

Distinguishing Technical Characteristics
Clockwise Balance Cock Screw Regulator Balance Balance at 4:30 Barrel at 12:00
Production: 1996 – 2005
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

Cal. 4S77, made from 1999 through 2005, is one of the most complicated automatic movements produced by Seiko. Complications on this modular movement include retrograde day, date by pointer, 24 hour subdial, and independently adjustable hour hand. It was part of the second “wave” of movements in the Seiko 4S family, which itself was derived from the historic Seiko 52 stream of movements. Cal. 4S77 is similar in design to Cal. 4S27, but with more upscale finishing and regulation for use in Credor watches. Unlike most 4S movements, Cal. 4S27 has 50 hour power reserve.

Most watches using this movement have the look of a chronograph, with subdials at 6:00 and 9:00 and a power reserve pointer near 3:00. A second crown at 2:00 on the dial adjusts the central 12 hour hand in 1-hour increments, leaving the 24 hour subdial as “home time.” Many examples include a rotating inner bezel with a third crown at 4:00, completing the chronograph look.

• A retrograde pointer at 2:30 shows the day clockwise on a “fan”
• A subdial at 6:00 shows the date using a small pointer
• A subdial at 9:00 shows “home time” using a hand on a 24 hour scale

Cal. 4S77 was used in the Credor Pacifique and Phoenix GCBG watch series from 1999 through 2005. Some reports suggest that it was introduced as early as 1996.

• 1999-2002 Credor Mechanical GCBG999
• 2001-2004 Credor Pacifique GCBG997
• 2001-2002 Credor Pacifique GCBG996
• 2000 Credor Phoenix 2000 Kumakawa GCBG987 (Limited Edition of 1000, introduced at BaselWorld 2000)
• 2002 Credor Phoenix FIFA GCBG977 (Limited Edition of 500)
• 2003-2005 Credor Pacifique GCBG975
• 2003-2005 Credor Pacifique GCBG973
• 2004-2005 Credor Pacifique GCBG971
• 2004-2005 Credor Pacifique GCBG969

Complicated Seiko 4S Movements

After 2000, Seiko had more diverse mechanical movements to choose from. The 4S family was moved upmarket as a base for modules to use in complicated upscale watches. The last 4S movement was retired in 2015.