7a38-6010, crystal code and replacement tips - Seiko & Citizen Watch Forum Japanese Watch Reviews, Discussion & Trading
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Old 04-22-2018, 10:24 AM   #1 (permalink)
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Default 7a38-6010, crystal code and replacement tips

I've checked the documentation available in the manuals forum, but I can't track down the proper replacement crystal sizing for a 7a38-6010. I picked up a junker on ebay that looks to have good lume but a terrible crystal. Does anybody know what kind of crystal it takes, and even better how to find this kinda info in the future?

Also, any gotchas around replacing crystals in these watches?

Thanks!
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Old 04-22-2018, 10:29 AM   #2 (permalink)
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285W26GN00
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Old 04-22-2018, 03:46 PM   #3 (permalink)
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Good luck with finding one at a reasonable price. Last time I saw a genuine Seiko crystal on eBay was over a year ago.

http://www.ebay.co.uk/p/Seiko-Glass-...040/1271022101



To fit a replacement crystal to a 7A38-6010, you first need to remove the bezel, because the bezel insert overlaps the crystal slightly. Then remove the dial / movement and the plastic Tachymeter ring and press the old crystal out from inside the watch case.
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Old 04-22-2018, 03:51 PM   #4 (permalink)
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Quote:
Originally Posted by flimshaw View Post
7a38-6010. I picked up a junker on ebay that looks to have good lume but a terrible crystal.
I this is the 'junker' you picked up:



I guess you're going to need a new bezel too.
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Old 04-22-2018, 04:07 PM   #5 (permalink)
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Ouch! for that kind of money you could probably get a sapphire crystal from crystaltimes.
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Old 04-22-2018, 06:35 PM   #6 (permalink)
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A sapphire crystal is an overkill and a waste of money. Besides, I guarantee the OP won't find one of the correct specifications. The Seiko p/n 285W26GN00 is a bit of a 'special' - it measures 28.5mm x 1.85mm thick, with a polished bevel edge. That bevel is needed to clear the underside of the bezel insert. There is no Sternkreuz equivalent. You could use any generic flat round mineral glass measuring 28.5mm x 1.5mm thick, but it will leave a gap around the edge of the bezel insert. You could alternatively try fitting a 28.5mm x 2.0mm thick generic, but chances are it will foul on the underside of the bezel insert. I did it myself once, but I really had to give that 2.0mm thick crystal some 'extra welly' to make sure it was pushed down low enough to clear the bezel insert.


Last edited by Dazzler; 04-22-2018 at 06:48 PM. Reason: Adding photo
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Old 04-22-2018, 06:40 PM   #7 (permalink)
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You can buy a generic stsupply for $12.50.

For that price I would give it a go. I have had some great success with their generics.


http://www.stsupply.com/catalogsearc.../?q=285W26GN00
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Old 04-22-2018, 08:58 PM   #8 (permalink)
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Quote:
Originally Posted by Dazzler View Post
A sapphire crystal is an overkill and a waste of money. Besides, I guarantee the OP won't find one of the correct specifications. The Seiko p/n 285W26GN00 is a bit of a 'special' - it measures 28.5mm x 1.85mm thick, with a polished bevel edge. That bevel is needed to clear the underside of the bezel insert. There is no Sternkreuz equivalent. You could use any generic flat round mineral glass measuring 28.5mm x 1.5mm thick, but it will leave a gap around the edge of the bezel insert. You could alternatively try fitting a 28.5mm x 2.0mm thick generic, but chances are it will foul on the underside of the bezel insert. I did it myself once, but I really had to give that 2.0mm thick crystal some 'extra welly' to make sure it was pushed down low enough to clear the bezel insert.
Crystaltimes would be exact specs if they make one, 50 is a bit much for a stock hardlex.
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Old 04-23-2018, 02:53 AM   #9 (permalink)
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...50 is a bit much for a stock hardlex.
Of course it is. But there were two people out there desperate enough to pay that rip-off price.
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Old 04-23-2018, 06:20 PM   #10 (permalink)
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Thanks for the replies! That was indeed the very ebay item I picked up. Lume is nice and white, all functions work, but the buttons are gluey and the crystal is a nightmare.

@Dazzler: The bezel is definitely stiff but clicking fine. I've done a crystal replacement on a 6139-8050, but never on anything with a rotating click bezel. Am I correct in thinking the process would be:

1. remove the movement and store in a safe place
2. remove the rotating bezel with a jeweler's knife
3. remove internal ring & use a crystal press to press the crystal out from inside the case
4. replace... gaskets etc? fuzzy on this part
5. press new crystal into place from outside
6. press rotating bezel into place from outside
7. replace movement and enjoy

The service manual didn't seem to have info for models with*the clicking bezel so I want to be sure I'm on the right track before I get started. Any other parts I should stock ahead of time? Anything I might need to fix/loosen the bezel clicking?

Thanks again, you guys are lifesavers.
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Old 04-23-2018, 09:15 PM   #11 (permalink)
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Aren't the SternKreuz XMF range bevelled?
In fact I remember buying one. Tomorrow morning I'll dig it out.
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Old 04-24-2018, 03:56 AM   #12 (permalink)
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Quote:
Originally Posted by rob3rto View Post
Aren't the SternKreuz XMF range bevelled?
In fact I remember buying one. Tomorrow morning I'll dig it out.
Some of them are - indeed they're intended as specific 7Axx replacements, like their p/n's XMF320.927 and XMF300.860.
But none of their XMF285.xxx's are suitable for this application.

Last edited by Dazzler; 04-24-2018 at 04:59 AM.
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Old 04-24-2018, 05:03 AM   #13 (permalink)
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Quote:
Originally Posted by flimshaw View Post
Am I correct in thinking the process would be:

1. remove the movement and store in a safe place
2. remove the rotating bezel with a jeweler's knife
3. remove internal ring & use a crystal press to press the crystal out from inside the case
4. replace... gaskets etc? fuzzy on this part
5. press new crystal into place from outside
6. press rotating bezel into place from outside
7. replace movement and enjoy ....

More or less, except with this particular watch case, the dial ring (Tachymeter) sits on top of the dial, rather than being sandwiched between the glass and / or the case / bezel. So, as you withdraw the dial / movement it will probably drop down with it. Careful it doesn't snag the hands.


Regarding point 4 - I tend to re-use the existing nylon crystal wherever possible (assuming it's undamaged). If you've ever tried fitting a new one you'll know the reason why !

Last edited by Dazzler; 04-24-2018 at 05:08 AM.
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Old 05-10-2018, 10:48 PM   #14 (permalink)
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UPDATE: the crystals on ST were pretty good actually! Definitely not an exact replica on the edge bevelling, but close enough and causes no problems with the click bezel. I cleaned and de-gunked the pushers but they still feel really gummy. All functions work though and there doesn't appear to be any rust or water damage. Just the rubber gaskets that are gumming it up?

The bad news:
I realized after I got it all together that one of the buttons looked like it was about to fall out. I opened it back up (after painstakingly getting the inner bezel aligned properly) and damn, looks like I lost TWO circlips! I didn't make careful note when I was putting it back together, and the case has been sitting out on my bench for a week so they aren't necessarily kicking around inside the movement... right? Ordered a handful from Esslinger but have to forego wearing it until I get that sorted.

Thanks for the help! It's coming along.
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File Type: jpg 7a38-new-crystal-and-cleaning.jpg (395.8 KB, 6 views)

Last edited by flimshaw; 05-10-2018 at 10:50 PM. Reason: embeeded image was too big
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Old 05-11-2018, 12:05 AM   #15 (permalink)
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Quote:
Originally Posted by flimshaw View Post
UPDATE: the crystals on ST were pretty good actually! Definitely not an exact replica on the edge bevelling, but close enough and causes no problems with the click bezel. I cleaned and de-gunked the pushers but they still feel really gummy. All functions work though and there doesn't appear to be any rust or water damage. Just the rubber gaskets that are gumming it up?

The bad news:
I realized after I got it all together that one of the buttons looked like it was about to fall out. I opened it back up (after painstakingly getting the inner bezel aligned properly) and damn, looks like I lost TWO circlips! I didn't make careful note when I was putting it back together, and the case has been sitting out on my bench for a week so they aren't necessarily kicking around inside the movement... right? Ordered a handful from Esslinger but have to forego wearing it until I get that sorted.

Thanks for the help! It's coming along.
Yeah you have to replace the pusher gaskets and they will feel like new.

The original Seiko pusher gasket is EC0060B0A

The E on this codes indicates that it is a special Seiko profile. Luckily Cousinsuk have reproduced these (EC0060B01) and they are super cheap!

They can be purchased as part of a kit of common Seiko and Citizen micro gaskets or in packs of 10.

https://www.cousinsuk.com/product/d-...o-ring-by-size

They are a bit of a pain to get on, but if you grease them first before you fit them.

The pushers will be as good as new!

Dan
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