Manufacturer | Seiko |
Caliber Number | 5206, 5206A (Seiko catalog number 52-06-1) |
Movement Type | Automatic, self-winding mechanical |
Diameter | 25.6mm |
Height | 3.95mm |
Jewels | 23 or 25 |
Beat Rate | 28,800 bph |
Lift Angle | 52 degrees |
Power Reserve | ~40 hours |
Rotor Style | Ball-bearing |
Hand-Windable? | Yes |
Anti-Shock Device | Diachock |
Hand Count | 3 |
Functions | Central hours; central minutes; central sweeping seconds; bi-lingual day/date at 3:00 |
Hacking Seconds? | Yes |
Quickset Calendar | Yes |
Country of Manufacture | Made in Japan |
Known Models | Seiko Lord Matic (Add your watch to the comments below…) |
The Seiko caliber 5206 (5206A) is a vintage automatic watch movement in the 52 or 5200 family of calibers. The 5206 was equipped with a day/date calendar complication and is found in Daini Seikosha produced Lord Matic watches from the early 1970s (1970~1973).
Some of the topics covered in this caliber listing:
Different Jewel Counts:
The Seiko calibre 5206A has two variants with different jewel counts: 23 or 25. The main difference appears to be that the 25J version includes an upper hole jewel for the barrel and an upper hole jewel for the 1st reduction wheel. Another difference is the part number for the rotor since the jewel count text is different depending on the number of jewels.
Day/Date System:
The day/date on the 5206 is the instant or “spontaneous” type, meaning it switches over at midnight. Both are “quickset” and the day of the week has a bilingual change-over system.
Seiko 5206 VS 5216:
Around 1972, the cal. 5206 evolved into the Seiko caliber 5216A with a more efficient calendar system, but also eliminated the “spontaneous” instant day/date changeover at midnight. Many of the parts are interchangeable, except for several parts for the day/date system. All this means is that rather than the day/date changing together instantly at 12:00AM, the date will change at 12:00AM and the day of the week will change about an hour or so after that.
With the 5206A system, the manual advancing of the calendar was much more sensitive compared to the updated 5216 (see the safe zone below).
Setting the Calendar:
To set the day/date, pull the crown out one click to calendar setting mode.
- To advance the date, turn the crown clockwise.
- To advance the days of the week, turn the crown counterclockwise.
To avoid damaging the movement in your 5206 powered watch, Seiko has issued the following precautions for calendar correcting:
- Safe zones for setting the date are with the hands set between 3:45AM and 9:00PM.
- Safe zones for setting the day of the week are between 7:00AM and 11:00PM.
Interesting side note: when setting the date, the mainspring also gets wound a little. This, of course, does not create an issue with over-winding (as an automatic movement, this caliber cannot be over-wound), but if the same calendar system was used on a manual-wind watch, it could potentially pose a problem with over-winding.
Video: Seiko 5206 Disassembly and Service
Additional Resources:
Recent Comments
Hi Omega caliber 571 and 570 escape wheel is same or different
Yep, 763e. That has to be it. Thanks for your confirmation. Many thanks
https://calibercorner.com/ronda-caliber-763e/
Ah, I believe it's a 763e Am I correct?
Glad you found it! https://calibercorner.com/ronda-caliber-763/
Without taking mine apart, I found the same exact watch with the Ronda movement. Face…
Hi Keith, please try posting a picture of the movement and watch in the forum.