Seiko caliber VK83 VK83A SII

Hattori SII Caliber VK83

Seiko caliber VK83 VK83A SII

Manufacturer Hattori aka Seiko Instruments Inc. (SII)
Caliber Number VK83, VK83A
Type Quartz (mecaquartz)
Diameter 13 1/2”’ (30.8mm x 29.10mm)
Thickness 5.10mm
Battery Cell Number 394
Frequency Unknown (please comment below)
Quartz Type Tuning fork type quartz crystal
Stem 351177/tap 10 or 351892/tap 11
Hand Sizes 1.50/.90/.32mm
Jewels 0
Functions Hours, minutes, small seconds, date, central chronograph seconds, 20 minute counter, 24 hour indicator
Country of Manufacture Japan (assembled)
Known Models Add to the comments below…

The Seiko SII caliber VK83is part of the hybrid mechanical quartz (mecaquartz) movement line. It is a chronograph movement that uses quartz technology for the main functions of the watch, and a mechanical module for operating the chronograph. Learn more here.

Time Module/Seiko states that the expected accuracy of this movement is less than +/- 20 seconds per month at normal temps. The battery life is about 3 years with normal operation.

Battery replacement:

After installing a fresh battery cell, remember to reset the circuit by touching the AC terminal of the circuit block (look for an arrow labeled AC pointing to a hole) and the switch spring with your tweezers.

Replacement prices of about $35.95 found online.

You might find the caliber VK83 listed as being produced by SII aka Hattori aka TMI (Time Module Inc) aka Seiko Instruments Inc. Learn more about the different names here. Other calibers with the same base movement are VK63 and VK67.

The front of the movement