Seiko 7A38 - by the numbers

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Forum Home > Parts Info, Tech Tips and Tinkering > Misaligned inner tachymetre 7A28-7069

Michael Plant
Member
Posts: 3

Hi all,

I've been a lurker here for at least two years but this is my first post. Several years ago my father picked up a 7A28-7069 from a friend in the air force and gifted it to me. It is in very nice shape and had recently been serviced with a new crystal fitted. Unfortunately, whoever did the work installed the tachymetre rehaut badly misaligned ( the first "a" in "Tachymetre" is at the 6 o'clock position). My local watchmaker won't touch it because he doesn't think he can get a  replacment crystal for it. Is this a job I can tackle myself (I've replaced lots of bezels/bezel inserts and have some experience getting the backs off watches and futzing around...)?

If so, any pointers? Thank you,

Mike.

August 7, 2016 at 10:10 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 12355

One of the easiest 'faults' to rectify, Mike. ;)

The plastic Tachymeter ring has a series of small pips moulded on its underside, which should engage cut-outs around the perimeter of the dial and ensure correct alignment, but you'd be amazed at the number of watch tinkerers who still manage to get it wrongly positioned. In most 'conventional' 7Axx's the Tachymeter ring is usually sandwiched betweet the bezel and the case, but free to rotate. In which case, you simply push it around to the correct orientation with the point of a wooden cocktail stick. Sometimes it just sits (loose) on top of the dial plates.


Goes without saying, you'll need to withdraw the crown stem and pop the movement out to re-position it.

I don't do 7A28's so I'm not familiar with this particular model, but here's a photo I've borrowed from SCWF, which may help.




One pointer (no pun intended), but I always align all the hands with '12' or '0' before removing a dial / movement. Less chance of damage if you happen to fumble it. ;)


August 7, 2016 at 11:39 AM Flag Quote & Reply

Michael Plant
Member
Posts: 3

Thank you so much - I'll give it a go. I'm a bit embarrassed as I searched the SCWF before posting here - missed that photo entirely.

Cheers,

Mike

August 7, 2016 at 11:42 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 12355

Mike.

There is another variation in the method of Tachymeter ring location and that's where it sits beneath an upper metal dial ring, which in turn is held in place by the crystal gasket. I've had a look at the parts list for the 7A28-7069 and there is no separate bezel listed. Which indicates it might fall into this category. Have a look at my photos of a stripped 7A28-7040 case in this thread.

Either way, unless the watchmaker who fitted the replacement crystal was extremely brutal and over-compressed the gasket, you should still be able to rotate the Tachymeter ring from underneath.


August 7, 2016 at 11:59 AM Flag Quote & Reply

Michael Plant
Member
Posts: 3

Ah, thank you. I haven't gotten around to opening mine up but will refer to both your first reply here and the thread you link to above when figuring out what to do. Hopefully I'll find time next week. Waiting for house guests to arrive now and have spent the day cleaning and tarting the place up!

August 7, 2016 at 6:00 PM Flag Quote & Reply

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