camrok
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Post by camrok on May 29, 2017 15:00:09 GMT -8
You may have caught my post a while back about resurrecting this digital solar Seiko a258.  The original xr9527 is no longer available. In the interest of science I have purchased the closest rechargeable capacitor. An MT920. The height is slightly different. (920 vs 927 in traditional batter cell size) I stuck my multimeter on it as soon as it arrived.  It didn't fire up initially and I stuffed around with spacers trying to rectify the height. Then I popped a standard sr920 in at 1.55v to check it... bingo it worked perfectly. Then I returned the mt920 and it worked well.  The display is a bit faint and definitely not as bright as the sr920. I have stuck it in the sun today and will see how it charges. I will test it on the multimeter again. Tonight. |
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tritto
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Post by tritto on May 29, 2017 15:45:58 GMT -8
An excellent experiment to document as there are plenty of old solar digitals about and no batteries. Sure, you can mod them to disable the charging circuit and put a regular battery in, but that defeats the purpose of having a solar digital watch.
So the MT920 is a 1.4v battery, or was that just the result of a low charge?
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Deleted
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Post by Deleted on May 29, 2017 15:59:23 GMT -8
An excellent experiment to document as there are plenty of old solar digitals about and no batteries. Sure, you can mod them to disable the charging circuit and put a regular battery in, but that defeats the purpose of having a solar digital watch. So the MT920 is a 1.4v battery, or was that just the result of a low charge? Rechargeable button cells are nominal 1.2V but when fully charged, be around what you saw on the meter. The display probably won't get any brighter but at least it is still perfectly serviceable as a time display  |
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camrok
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Post by camrok on May 30, 2017 4:06:01 GMT -8
Update: the results are in after a full day of autumn non direct sun- 1- crisp black LCD segments.  2- multimeter @ 1.685 up .3v  3- Light works.  Conclusion. The MT-920 is a suitable replacement for the XR9527 A follow up study is required to see how it holds its charge! |
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tritto
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Post by tritto on May 30, 2017 4:08:04 GMT -8
Excellent work and great news.
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Deleted
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Post by Deleted on May 30, 2017 8:00:23 GMT -8
Update: the results are in after a full day of autumn non direct sun- 1- crisp black LCD segments. 2- multimeter @ 1.685 up .3v 3- Light works. Conclusion. The MT-920 is a suitable replacement for the XR9527 A follow up study is required to see how it holds its charge! Now that is interesting. The voltage on your meter shows this cell to be a 1.5V cell. I guess the slightly different chemistry of these button cells compared to the bigger Lithium Ion AA, AAA, etc. allows for the higher voltage. I am glad to see that it took a full charge and the display is so sharp With any luck you will find a fresh crystal and the watch will be a real eye popper :dance: |
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Post by sumonini on Mar 6, 2023 13:17:44 GMT -8
Hi,
Sorry - I know this is an old thread, but I find myself in the same position - I have the same watch and I am wondering which battery to use!
Curious to know - did the MT920 hold up well and allow for continuous, good use?
Thanks in advance
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camrok
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Post by camrok on Mar 21, 2023 2:30:03 GMT -8
It’s been a while sorry. Yes the 920 was fine from what I remember. It just needed some padding to make sure it sat snugly in the module
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Post by sumonini on Mar 30, 2023 0:47:10 GMT -8
It’s been a while sorry. Yes the 920 was fine from what I remember. It just needed some padding to make sure it sat snugly in the module Many thanks for the reply - that's great to know. I actually have this and a Casio Solar DW-2000 so planning on trying it on that too. |
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Post by sumonini on Mar 30, 2023 0:49:08 GMT -8
It’s been a while sorry. Yes the 920 was fine from what I remember. It just needed some padding to make sure it sat snugly in the module Also - I just want to add my thanks and appreciation for the original post, very informative and detailed - extremely useful even after these years! |
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camrok
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Post by camrok on Mar 30, 2023 19:46:20 GMT -8
It’s been a while sorry. Yes the 920 was fine from what I remember. It just needed some padding to make sure it sat snugly in the module Many thanks for the reply - that's great to know. I actually have this and a Casio Solar DW-2000 so planning on trying it on that too. They are also not that expensive and from memory the cap I bought for the Seiko was marketed for a Casio solar. |
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