Seiko Grand Quartz 9943-800A on my bench

vienna · Jan 8, 2026

For the first time on my bench, a twin quartz thermo compensated 9943 movement from 1978. The second quartz is used for the temperature correction, both signals from the regular and the auxiliary quartz crystals are processed and the corrected signal goes to the coil to initiate the induktive field to move the rotor.

it‘s a beautiful movement, and the textured blue dial with the highly polished markers is outstanding. The case us allready cleaned, movement will follow in the coming days.

Since I have two incoming vintage quartz testers, one of them a Seiko QT 77, I will also regulate the movement according to the service manual.

Enjoy the pics and kind regards,

Max

vienna · Mar 3, 2026

As good as it gets 😁

HamDoctor · Mar 3, 2026

I really love these Seiko Grand Quartz watches. I'm just thankful that there's still people about who are disdaining quartz and don't consider these "genuine Grand Seikos", otherwise these would be unaffordable, and rightfully so. A watch that is almost 50 years old and was rated to +-10 seconds per year? Where else does something like this exist? (Besides the Twin Quartz 9983 Superiors, of course...)

I always like to recommend this article by The Grand Seiko guy, it has a very good insight into the place and history of these watches:

https://thegrandseikoguy.substack.com/p/a-history-of-grand-seiko-1975-to-1988

And finally, here's mine:

Seiko Grand Quartz 9943-8000 Wristshot 03.webp

Seiko Grand Quartz 9943-800A on my bench

vienna

vienna

HamDoctor

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