Seiko 7A28 Movement Details

Seiko caliber 7A28 is an analog quartz watch movement produced from around 1982.

Sub-brands: Sports 100, Speedmaster
Battery:SR936SW / 394 (Silver oxide)
Accuracy:±15 seconds/month
Day / date?No
GMT / world time?No
Chronograph?Yes
Hacking?No
Rate:32,768 Hz
Number of jewels:15
Size / diameter:29.0
Height:3.5mm
Stem code: 354726
Development division:Suwa (Nagano)
Notes:The world's first analog quartz chronograph and, unlike many other quartz chronographs, uses metal rather than plastic parts making it fully serviceable. Used in watches supplied to the British and South African air forces. Has a battery life indicator function. The same as cal. 7A38 but without day and date display.
PDF guides: Technical guide for 7A28A
Related movements: 7A34 7A36 7A38 7A48 7A54

Articles