Seiko Caliber 5R65

Seiko caliber 5R65 found in the Seiko Marinemaster Golden Tuna. This movement has 30 jewels and a power reserve of 70 hours. Made in Japan.

Accuracy:

According to Seiko official documentation, they claim that this movement has an accuracy rating of +/- 15 seconds per month in normal operating conditions and temperatures (-10 ~ +60 degrees C).

Power Reserve:

The caliber 5R65 has a power reserve of 70 hours. Once the mainspring is fully wound, it cannot be over-wound thanks to a slipping mechanism that prevents the mainspring from over-winding. Watches with this caliber typically have a power reserve indicator on the dial. According to Seiko:

The mainspring of the watch becomes fully wound when it is worn for twelve hours for three to five consecutive days. In a case where you wear the watch for a short period of time each day, observe the power reserve indicator to check the level of the remaining power. If necessary, manually wind the mainspring.

Smoothness:

This Spring Drive automatic movement is most notable for it’s super smooth Glide-Motion second hand. You can see it up-close in action here.

5R65 VS 5R64:

There is a similar caliber 5R64. The 5R65 has 30 jewels and the 5R64 has 32 jewels. Both of these calibers have the same functionality with the main difference being that the 5R65 has a central sweeping seconds hand and the 5R64 has a small seconds hand.

5R65 VS 5R66:

There is also a caliber 5R66 with a GMT complication. All other specs are the same other than the GMT.

Crown/Stem Removal:

To remove the crowna nd stem on the 5R65, make sure the crown is in winding position. Press the detent button (setting lever) gently until the stem can be extracted. Pressing too hard can damage the datewheel.

Service/Repair:

At the time of this post, Seiko calls for all repairs and overhauls to be sent to Seiko Watch Company in Japan for service. They will not provide any movement parts to watchmakers.

Resources:

• All about the Seiko Spring Drive
• Caliber 5R65 official manual

Note: a photo of this movement is desperately needed to complete this listing. If you have an original photo that can be posted, please let us know.