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Discussion Starter · #1 · (Edited)
Hi everyone, I'm new here, but have enjoyed owning a Citizen Promaster NY0040 automatic for several years.

I would like to share some stuff I learned while trying to improve the accuracy of the watch.
I'm curious to know what your experiences are with this.

When I bought it, the Citizen was about 10 seconds too slow, daily.
I searched for information on how to tweak the accuracy and found a clear photo of what I needed to do. So I decided to have a go and try to get it as accurate as possible.

(sorry, can't post the photo here due to my newbie status :rolleyes:)

Inside the movement (in my case a Miyota 8203 but the Seiko movement in the photo I had found had a similar part) there is a sort of “regulator arm” marked with a + and - symbol, that can be pushed in either direction in order to tweak the accuracy of the watch.

By tweaking this regulator by tiny, nearly imperceptible amounts and then checking again after a week or so and then tweaking again I managed to gradually increase the accuracy of the watch. After several weeks of trial and error I got the accuracy down to more or less 2 seconds per day.

I imagine many of you know this already but I didn't at the time: while keeping track of the offset every day I noticed the accuracy of the movement depended very much on the resting position of the watch when it was not being worn.

The watch had an offset of + 1.5 seconds per 15 hours when worn on my wrist.
If during the night the watch was resting on its back with the dial up, or on its face with the dial down, the offset would be +1.5 seconds after 9 hours.
When resting on its side with the crown down the offset would be -3.5 seconds. With the crown up it would be +1 second.
And if the watch was vertical, with the 12 o’clock up, the offset would be -2 seconds and with the 12 o’clock down it would be -5 seconds.

That's great actually: you can easily correct the daily offset by simply placing the watch in a certain position at night, or perhaps on weekends.
I wonder if these variations are unique to each movement, or do other watches behave in similar ways?

Anyway, I hope this might be useful to someone! :)

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