Looking for tech sheet for Rare Seiko Dolce 8N41 or 8N20

Alex Hamilton

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Jan 29, 2021
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I have a rare Seiko Dolce 8N41-5040 which is a very accurate quartz movement that can be regulated to 20 spy. I have looked everywhere including AWCI's database and it just does not seem to be available anywhere. There are 6 dip switches on the movement for regulation, but I don't know what's what. You guys are my last option. If anyone has access to the tech sheet or know how this is regulated, I will be eternally in your debt.
Thank You.

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Chris Radek

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Apr 13, 2014
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I suspect they have binary weighting, each switch having twice the effect on rate as the previous. It would be very straightforward to flip them one at a time and measure the effect on a timer. Mine reads to 0.01 sec/day in just a few seconds.
 

Alex Hamilton

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I suspect they have binary weighting, each switch having twice the effect on rate as the previous. It would be very straightforward to flip them one at a time and measure the effect on a timer. Mine reads to 0.01 sec/day in just a few seconds.
Hi Chris,
Thanks for the reply. I have the Handy Tech 2 which also reads to 0.01 spd, but I am unfamiliar with the procedure to "flip the Switch". Since I don't know if the tech sheet will ever show up, if you have a chance to elaborate it would be much appreciated.
 

Alex Hamilton

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it seems like worst-case 20 seconds a year shouldn't really be an issue? in other words your watch is way more accurate than a normal quartz watch so do you have a concern about the timekeeping?

not what you're looking for but I did find the users guide at the link below.




https://storage.seikowatches.com/production/files/2018/03/20/143934646414/8N41.pdf
Hi John,
Thanks for the reply and the user manual. Unfortunately it's running at around + 30 spy. In the HAQ world that is equal to a Hamilton 4992b running +/- 60. Its a beautiful watch with a solid 10k gold case that just needs a little love to make it perfect.
 

John Runciman

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running at around + 30 spy.
one of the problems when timing something that is seconds per year that whatever your timing against has to keep better time. For instance the reference to the timing machines that will time to .01 seconds per day looks fine on paper but how accurate is its time source for timing for a year? so basically you have to time against something that's traceable to some national standard and atomic clock someplace

then sometimes a minor problem I have when answering questions is not paying attention the title and vversus the text in the body. As you're looking for a tech sheet but in the title you're looking for 2 separate tech sheets had I have noticed that I would a given you this last reply. But I didn't include it because it's not the same number as the one in the text. The just as a reminder if you put something in the title also put it in the text for us people it don't pay attention to both simultaneously..

then you may find the link below interesting. They service Seiko watches looks like the cost of servicing yours is $154..that it does say they'll adjust the timing to specifications worst case you go this route.


Serviceprice - SeikoServiceCenter
 

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Alex Hamilton

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Jan 29, 2021
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one of the problems when timing something that is seconds per year that whatever your timing against has to keep better time. For instance the reference to the timing machines that will time to .01 seconds per day looks fine on paper but how accurate is its time source for timing for a year? so basically you have to time against something that's traceable to some national standard and atomic clock someplace

then sometimes a minor problem I have when answering questions is not paying attention the title and vversus the text in the body. As you're looking for a tech sheet but in the title you're looking for 2 separate tech sheets had I have noticed that I would a given you this last reply. But I didn't include it because it's not the same number as the one in the text. The just as a reminder if you put something in the title also put it in the text for us people it don't pay attention to both simultaneously..

then you may find the link below interesting. They service Seiko watches looks like the cost of servicing yours is $154..that it does say they'll adjust the timing to specifications worst case you go this route.


Serviceprice - SeikoServiceCenter
John,
It's my understanding that the analyzer I'm using, Wischi Handy Tech II, is measuring the inductive rate of the stepping motor which is the rate that the watch will actually display. I would think the software in the analyzer would be pretty accurate. Of course, accuracy on the wrist could be different, you would think movements at this level would be pretty stable.
I also apologize for the confusion in the title. The tech sheet I was looking for was the 8N41. That's the movement in the watch i have. The second movement should have read 8N65 which I believe has a similar adjustment system. Once I posted it I didn't notice the error until it was pointed out.
Thanks again for your time.
 

John Runciman

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It's my understanding that the analyzer I'm using, Wischi Handy Tech II, is measuring the inductive rate of the stepping motor which is the rate that the watch will actually display. I would think the software in the analyzer would be pretty accurate.
when I was trying to figure out was were going to ignore the accuracy of the machine because it looks really really good. It is a really nice stable oscillator they even give you the specifications for the first year they look really really good. But were still stuck with some other problem? In other words the resolution of your machine if you look at the manual is 0.01 seconds went on the seconds per day scale. If you go to the seconds per month he only have a resolution of one second. now is where I'm not a math whiz but in my simple math skills the resolution of the machine becomes a problem. So we look at the worst-case timing of 20 seconds and you look at that per month that would be 1.66 seconds on the month scale you're going to be off because you only get a resolution of one. Looks like the second per day scale would be better much better get you much closer. But there's still a minor little problem?

interesting problem when your measuring stepping motor frequency is if the watches using digital regulation then you have to have the right gate time or you're not going to get the right rate. Then it be nice to have the tech sheets because maybe there's something else you're supposed to be doing? I'm attaching the battery cross reference chart from Seiko which is interesting because it has additional specifications. PDF page 9 towards the bottom answers questions that lease that I have. So you find out you need a gate time of 10 seconds. Then there's a note on the very bottom of the page you need that the crown in the right position it be interesting to see if that changes your timing at all?
 

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Alex Hamilton

NAWCC Member
Jan 29, 2021
22
3
3
61
Carolina Beach
Country
when I was trying to figure out was were going to ignore the accuracy of the machine because it looks really really good. It is a really nice stable oscillator they even give you the specifications for the first year they look really really good. But were still stuck with some other problem? In other words the resolution of your machine if you look at the manual is 0.01 seconds went on the seconds per day scale. If you go to the seconds per month he only have a resolution of one second. now is where I'm not a math whiz but in my simple math skills the resolution of the machine becomes a problem. So we look at the worst-case timing of 20 seconds and you look at that per month that would be 1.66 seconds on the month scale you're going to be off because you only get a resolution of one. Looks like the second per day scale would be better much better get you much closer. But there's still a minor little problem?

interesting problem when your measuring stepping motor frequency is if the watches using digital regulation then you have to have the right gate time or you're not going to get the right rate. Then it be nice to have the tech sheets because maybe there's something else you're supposed to be doing? I'm attaching the battery cross reference chart from Seiko which is interesting because it has additional specifications. PDF page 9 towards the bottom answers questions that lease that I have. So you find out you need a gate time of 10 seconds. Then there's a note on the very bottom of the page you need that the crown in the right position it be interesting to see if that changes your timing at all?
Hi John,
The Value Checking PDF is a great source of information. I had a copy, but this will be a great source for others in the future. I agree that SPD is the most accurate and the timing interval length is adjustable. I thought the tech sheet might explain the procedure for adjusting the switches but it appears to quite elusive.
Thanks for your time and input. Its greatly appreciated
 

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