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Seiko 4R38 Movement Details

Thumbnail image of Seiko movement 4R38A (the same as NH38) in model 4R38-01N0. Seiko calibre 4R38 is an automatic (with hand winding) watch movement. Production started around 2011.
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Sub-brands: Presage
Power reserve:41 hours
Accuracy:+45/-35 seconds/day
Day / date?No
GMT / world time?No
Chronograph?No
Hacking?Yes
Rate:21,600 bph
Number of jewels:24
Lift angle:53º
Size / diameter:27.0mm
Height:5.32mm
Notes:Referred to by Seiko as an "open heart" caliber, because of the balance wheel being visible from the dial side. The same as cal. 4R39 but without a 24 hour indicator. Also sold as NH38.
PDF guides: Technical guide : 4R38A & 4R39A
Related movements: 4R35 4R36 4R37 4R39 4R71 4R72

Part Codes

Stem code: 351200 (tap 10)
Balance wheel code: 310198
Mainspring code: 201083
Screw codes: 012168, 012354, 012420, 012919 (ratchet wheel screw)

Videos

Images

Seiko movement 4R38A (the same as NH38) in model 4R38-01N0.
Seiko movement 4R38A (the same as NH38) in model 4R38-01N0. Photo by Ethan Rougon.
Seiko model 4R38-01N0.
Seiko model 4R38-01N0. Photo by Ethan Rougon.
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