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Chronomaster: 4 1/2 sec band over 5 years with new movement; what do I do now that batty is dead?

1769 Views 13 Replies 7 Participants Last post by  Hans Moleman
I bought my Citizen Chronomaster through Katsu Higuchi in Japan in 2007. Subsequently I posted much data here at Watchseek showing how the watch rapidly sped up over time and way out of spec, repeating that bad behavior after going back to Japan for service. Finally Higuchi decided it needed a new movement and in fact after that it performed MUCH better. I'm enclosing a graph showing that in the ~5 years it ran on its latest battery the watch stayed within a 4 1/2 second band compared to UTC, although that would not have been true for much longer.

But now the battery is dead and the watch is out of warranty. Higuchi did not reply to my last request for information about how to get the battery replaced and the watch regulated.

I have two questions for you better-informed people.

1) How can I get the job done by Citizen, presumably in Japan?

2) I can replace the battery myself, and grease the o-ring. I can certainly NOT regulate the rate, and beyond that I'm worried that the rate and TC parameters might be stored in volatile memory and would be lost if the battery is changed. Does anyone have experience changing the A660 battery at home?

Any help will be greatly appreciated!
Text Line Plot Slope Pattern
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Thanks, guys, for your comments. And Hans, for explaining why my Citizen lost two seconds and not only one. I suppose that this is more likely to happen when the battery has weakened.
I see that the Grand Seiko has a mechanical control for rate adjustment. It's not clear to me whether that changes an internal digital value or an analog trimcap, but in any case it is nicely accessible. The online photo of the A660 movement shows no access to the inside other than by several probe-able electrical contacts. I'm not ready to try to guess how to use those.

Tom, here is an old photo of my Chronomaster on my timing setup. It looks good as new today after being worn for most of 12 years.

Batteries are arriving from Amazon on Tuesday, when I will install one unless something changes my mind before.


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Ok, I replaced my Chronomaster battery. The last person to replace the back in Japan torqued it down very hard; I needed to make a simple but sturdy jig to hold the watch case when I removed the back.

Anyway, in the few days on the new battery the watch has been running fast at an average of about 4.1 seconds/year, worn 24 hours per day except while showering or measuring. As is my habit, I include a graph. The variation in slope among the segments may be due to ambient temperature changes.

Thanks for your comments and suggestions! Text Font Line Rectangle Parallel

wbird: hmm, I didn't look into this. I just replaced the battery with a drugstore Duracell 370/371. Oh well, when this cell runs out I'll probably be ready to set the time again anyway.
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