[amh82]

I bought a 7549-7010 Tuna from this forum a few weeks back, but when it arrived I found that the second hand was bent and that the Day wheel did not click over properly - neither of these points had been mentioned by the seller!

I got around to taking a look yesterday. The day wheels was easy enough, seems like it wasn't in place correctly.

The second hand, at closer look, was bent at both ends - almost like it had been done for a reason.

I straightened it as best I could, but it also bent in the other plane (i.e. as you look down on it, it's bent) - so it is better than it was, but I will be on the lookout for a new one.

Anyway, I put the hands back on and refitted the movement. Slipped the battery back in...........hmmm, that's not right. The second hand was just ticking back & forth.

So I removed the movement, checked it over, put stem back in, and it was running fine. Put it back in the movement, it stops.

I loosened the case back a bit and it would start running again. It seems that the second hand is fouling the crystal.

I double checked it was fully seated, which it was. Refitted a last time - but I still have the same issue. I'm pretty sure this is why the second hand had been bent down at both ends - but why!?

I'm wondering if the crystal is the correct one. Does anyone know what the profile is like on the inside for these? Should it be flat or internally domed?

Other option is that a gasket is missing so that the crystal is sitting lower than it should be, but if it's an L gasket, the crystal would be loose.

I need to strip the case properly to have a better look, but I'd like to get an idea of whether the crystal could be the problem.

Anything else it could be? The movement looked clean and original, but I have not stripped it down to see if any bits have been swapped over incorrectly.

Any suggestions would be much appreciated

 

[7s26b]

Hi, it should be a domed crystal - here's the tuna crystal reference . And maybe there's another possibility - the second hand pinion height? http://www.thewatchsite.com/12-reference-articles-faq-model-guides/130-seiko-tuna-shrouded-divers-crystal-guide.html

 

[amh82]

Hi, thanks, I had already had a look at that.

Mine is domed externally, but not as high as some pics I have seen, but should the interior of the crysral be domed as well, or flat?

 

[deco]

Hi Andy,

I found the original one and the interior of the crysral is domed too

 

[nzwatchdoctor]

Hi, it should be a domed crystal - here's the tuna crystal reference . And maybe there's another possibility - the second hand pinion height? http://www.thewatchsite.com/12-reference-articles-faq-model-guides/130-seiko-tuna-shrouded-divers-crystal-guide.html

Domed inside.
I've just finished restoring one for a customer and got him a replacement glass - costly but correct.

Re the secondhand pinion - this movement has the longest pinion of all the 75XX series movements. Hence why the domed glass.

 

[amh82]

Thanks for confirming guys

I will remove the crystal today or tomorrow and take a better look at it.

 

[amh82]

OK, bit of a bump - but I had my 7549-7010 apart today as it was annoying me that I had not worn it for months.

I removed the crystal and it has a very subtle double dome, put a straight edge across the internal edge, there is approximately 1mm of internal dome in the centre. Does that sound right or too shallow?

Also, some of the later tunas have a spacer ring under the crystal gasket, should the 7549?

Last thing! With the crystal retaining ring, should it be nipped up tight or can it be fully tightened, to the bottom of the thread maybe? I was worried about over tightening and tearing the gasket or cracking the crystal!

 

[7s26b]

OK, bit of a bump - but I had my 7549-7010 apart today as it was annoying me that I had not worn it for months.

I removed the crystal and it has a very subtle double dome, put a straight edge across the internal edge, there is approximately 1mm of internal dome in the centre. Does that sound right or too shallow?

Also, some of the later tunas have a spacer ring under the crystal gasket, should the 7549?

Last thing! With the crystal retaining ring, should it be nipped up tight or can it be fully tightened, to the bottom of the thread maybe? I was worried about over tightening and tearing the gasket or cracking the crystal!

Yes, the tech pdf shows a holding ring for glass gasket, and the glass fixing ring should also have a gasket underneath - to allow the ring to be tightened down with a case back tool and not damage the glass.
http://thewatchsite.com/d1/files/Seiko Technical Manuals/7548A_7549A.pdf
Here's the cross section of a 1000m one to show the thread/gasket relationship

 

[amh82]

Just to follow this up, a few months back I bit the bullet and bought a 1:1 sapphire crystal, as I was convinced it had to be a problem with incorrect crystal.

Sure enough, fitted the new 1:1 crystal and now the second hand does not touch - the old crystal did not have enough internal dome.

I straightened the bent hand as best I could, but have recently found a NOS 7549 second hand, so will use that once it arrives.

I tried a 7548 second hand but it did not fit, whether it was too far out, or just needed broaching I am not sure.

 

[tritto]

Hi amh82. Where did you get your 1:1 replacement? Was it sapphire or Hardlex and did you go for AR? I've got a Hardlex replacement on the way from Spencer Klein over on WristSushi. He's very well regarded so I assume his will also be a good 1:1 copy. I'm not a huge fan of the cool blue tint given by the AR so went for a non-AR option.

After reading your earlier experience I decided not to take a punt on eBay listings for sapphire crystals.


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[amh82]

Hi tritto,

I got the sapphire from a guy on ebay.

His id was crystal times.

I was unsure about the AR initially, but decided to try it - I'm happy with the result, fairly subtle.

 

[tritto]

Thanks mate. I've seen crystaltimes but never bought any of their stuff. Good to hear their product was good.

How about some pics when you've got that new seconds hand fitted ;-)


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[diesel powered seiko]

Crystal Times have always impressed me with their crystals (maybe I'm easily impressed? ). Their service is good to.
Regards, David