Seiko 7A38 - by the numbers

I've got an interesting little challenge set for me this weekend. As it says in the title.

Word of my 'fame' is spreading at work.  A chap I know and had previously noticed wearing a rather nice looking all-titanium Seiko chronograph asked me if I could fit a new battery for him. I hadn't looked that closely at it before, but from the 1980's style had incorrectly assumed it was a 7T32 of some sort. When he handed it over, I realized it wasn't, but a dreaded 7T62 ! 

My initial reaction was to say No, Sorry - I didn't want to take the risk of buggering up his watch. 

This is a partial copy of the email I sent him yesterday evening:

I’m not sure how widespread this problem with the 7T62 is. 

Here’s an instance I remember fairly well, because I contributed to the thread (as ‘Seiko 7A38’) on another forum:

http://forums.watchuseek.com/f21/7t62-movement-button-doesnt-work-after-battery-change-757647.html

It’s been reported (on and off) since 2008: 

http://www.network54.com/Forum/78440/thread/1208667043/1208780497/Any+problems+with+Seiko+7T62+movement--- 

These may come in handy (for both of us): 

http://www.seikowatches.com/support/ib/pdf/SEIKO_7T62.pdf 

http://service.seiko.com.au/i/seiko/documents/technicalguides/7T62A-7T92A-7T94A_c.pdf

Wish me luck !  

This is the watch in question - a 7T62-0FD0 SNA559P1

Perhaps you can see what I meant by the 1980's styling - anodized titanium and two tone. By modern(ish) standards, it's also relatively small - only 37.5mm in diameter. It's also incredibly light. The serial # on the one I'm currently working on begins 87xxxx, so I'd suspect it was manufactured in July 1998 (rather than 2008). Though when I tried using John Gauch's Seiko Watch Production Date Calculator it came up as 'Unknown' - which probably means he hasn't yet added the 7T62 to his look-up table yet.

Here's a photo I took of it earlier this afternoon - as received. Note the chrono' hands (sweep for 1/5 second and 12 o'clock sub-dial for 60 minutes) are all over the place, rather than zero'd. Something which concerned me a bit - before I'd even unscrewed the case-back.

Et voilà ....

As you can see from the finger-marks it's had at least one battery fitted before. It was a Seiko SR927W, so I replaced it with a Maxell #399 direct equivalent. There's no AC reset needed (as with a 7T32). Fortunately when I turned it over, it had started ticking away merrily and the chrono' hands were static - in exactly the same place. Sigh of relief !

I zero'd the chrono' hands using the procedure shown on page 7 of the user manual I'd linked above (mostly for my own benefit):

Worked perfectly first time. 

So after reading all those tales of 'doom and gloom' on other watch forums, I'm pleased to say I didn't encounter any problems at all.

Or maybe just one small unrelated issue. I told the watch's owner that if everything went well, I'd replace the scratched crystal at the same time. The tiny release lever was initially rather reluctant to allow me to withdraw the crown stem, but I got there eventually and popped out the movement, which like other 7Txx's, carried on ticking away without the stem connected. I'd already guessed the crystal was a 31.0mm and around 1.5mm thick, so I'd been planning to replace it with a Sternkreuz MSM310, of which I've got a few in stock.

It came out cleanly and measures 31.0mm x 1.65mm thick. But it also has a gold decorative rim on the underside, which is just about visible in my Q&D photo. Sounds familiar ?

The Seiko p/n for this particular crystal is 310P03HB0A. It's normally only used in the 7T62-0FD0 SNA557P1 and SNA559P1.

But occasionally found in the odd 7A38.  Here's a partial quote of Simon's post dated March 8th last year from this thread:

My newest ........ that would be this - a 7A38-7180 in black:

which even before it arrived,  Paul had pointed out that it didn't look 'quite' right - with the gold inner ring above the tachymeter ring.

I hadn't spotted this - having just assumed this was the way it was meant to be - picking up those gold highlights 

This picture tries to show this ring a bit better:

Well, once Paul had pointed this anomoly out, and the watch had arrived I just had to see what this gold ring actually was. Popping the crystal out revealed that it was a transfer, applied to the underside of the crystal.

I did consider removing the transfer, but instead ordered a Sternkreuz MSM 310 crystal, which after it arived today I fitted.

This picture tries to show this ring a bit better:

Simon had indeed captured 'the gold ring' far better than I had (spectacularly failed to do so) in my previous photo of the 7T62-0FD0.

Suspecting that it was probably the correct p/n 310P03HB0A crystal I needed, I emailed Simon a 'begging letter'. He duly obliged. 

The crystal arrived yesterday; I fitted it about 10 minutes ago. Not the best of photos, but this one does show the decorative gold ring: