Seiko 7A38 - by the numbers



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Sir Alan
Posts: 457

I quite like the moonphase complication, so when a 7T36 came up on ebay recently I decided to go for it.

Interest was surprisingly lacking - I won it for the opening bid of £50. The listing did come with the all too familiar "was working when it last had a battery in it" line, which from experience can mean the watch is as dead as a dodo.

It arrived last week in a very grungy state, both inside and out.

Opening it up I wasn't sure what to expect - there was a lot of debris but no specific signs of battery leakage or water ingress.

I popped a battery in, and .......................... it started working :D

Oh happy days.  I'd been looking around for a donor watch incase this one was dead, but they seem pretty scarce.

I decided to clean it up, which I assumed would be pretty straightforward.

Removing the crowns was easy, but getting the movement out proved much trickier. It just wouldn't come out no matter how I angled or levered it.

The next thing I knew one of the sub-dial hands had popped off (as the dial started to come away from the movement. Then two more came off :roll:

I was being as careful as I could, but at this point I was pretty committed.

With the dial quite loose, I got the movement out and rescued the hands. I could see that the 3 pushers were fouling on the movement/dial.

Luckily, no damage was done (I've had the sub-dial hands pop off before when working on the 7T34 movements).

What was interesting about the pushers was that instead of those pesky little metal retaining c-clips, this watch used green plastic cylindrical c-clips. Much easier to get off (and to re-fit when I put it all back together).

I assume that I should have removed these while the movement was still in the case, then withdrawn the pushers to allow the movement to come out without fouling.

A lesson learned (#1).

Interestingly, the tachymeter ring is metal, not plastic.

I took all of the hands off to clean the movement and dial up.

When it came to re-fitting them I had another heartstopping moment fitting the main hour hand.

Usually this is the easiest hand to fit (having such a large diameter hole), but when I fitted this one, it sat down at an odd angle. Hmmmm.

Looking through the loupe I discovered that the pinion (?) that it fits over is made of plastic (not the metal I was expecting) and that I hadn't centred it correctly. Doh!!!!

I was really worried that I'd ruined things, but re-fitting the hand much more carefully I was able to get it correctly centred and all worked fine.

Lesson #2 (a big one).

So, a lot of differences here from the 7T32, 7T34 and 7T59 movements I've worked on previously.

Here is the watch - I need to find it a bracelet (or maybe a strap):

it's a 7T36-6A40. Keeping time perfectly. :P

August 28, 2012 at 7:15 AM Flag Quote & Reply

Posts: 55

Damn, thats really nice Si. Kudos on bringing it back to life!



August 29, 2012 at 7:55 AM Flag Quote & Reply

Site Owner
Posts: 12667

Have to go along with you there, Daz - though Simon knows I'm not a fan of 4 sub-dials, with or without moon-phase nor date pointers. 

If you think about it, Seiko had to have a moon-phase variant in the 7Txx line-up, or risk losing their previous 7A48 customer base.

Seems they may have re-used one or two 7Axx designs in the 7T36's. Does this look vaguely familiar to anybody ?

August 29, 2012 at 8:45 AM Flag Quote & Reply

Sir Alan
Posts: 457

I finally got round to taking some shots of the inside of this watch, and in particular the plastic c-clips that keep the pushers in place:

as I said in my first post, it wasn't obvious that to get the movement out (and back in again) it is necessary to remove the pushers.

This shot shows har far they protrude into the case:

and here, with the clip on:

and finally a shot of the clips:

they look to have the same side profile as the metal ones.

They are much easier to remove than the metal ones, and even easier to fit back on. But, just as easy to lose if they ping off.

November 6, 2012 at 11:00 AM Flag Quote & Reply

Sir Alan
Posts: 457

I picked this up quite a while ago - its a 7T36-6A10.

Yesterday I was having a collection assessment, partly to work out which watches (if any) might be on the transfer list. 

This one got selected as a non-wearer, but when I looked more closely at it, I realised just how nice it actually is.

The dial has a wondeful silvery tone to it and the sub-dials are flecked metallic.

I gave it a new crystal, re-positioned the bezel, and the chrono second and minute hands and voila - a super little watch.

Definitely NOT going. 

What was I thinking?  :roll:

December 25, 2013 at 7:07 AM Flag Quote & Reply

Posts: 508

Actually it does look very nice, I got one too, not working, but in dual tone version (7T36-6A30) I do have a working movement, so it will be a simple swap:

The conditions are pretty good, only small scratches on the glass and little wear and discoloring on the bracelet.


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December 25, 2013 at 9:26 AM Flag Quote & Reply

Posts: 508

After a movement swap, here is my 7T36-6A30 in all its functioning glory (I still had to set the date and alarm in this pic):


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December 26, 2013 at 11:59 AM Flag Quote & Reply

Sir Alan
Posts: 457

Nice George. These bracelets are very comfortable aren't they.

December 26, 2013 at 1:11 PM Flag Quote & Reply

Posts: 508

Indeed. Remember my water damaged 7T36? Well my son asked me to "repair it", contrary to my objections. I wanted it to stay as original as possible, but I finally agreed to change the dial with a NOS black one. This is the final result:

Sorry for the really bad light, it was late at night and illumination was provided by a neon light...


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January 17, 2014 at 2:10 AM Flag Quote & Reply

Posts: 6

GeorgeClarkson at December 25, 2013 at 9:26 AM

Actually it does look very nice, I got one too, not working, but in dual tone version (7T36-6A30) I do have a working movement, so it will be a simple swap:

The conditions are pretty good, only small scratches on the glass and little wear and discoloring on the bracelet.

Is there anyone still active on this thread regards a 7T36-6A30? I have one and have multiple questions that I'd really like to ask about it, especially regards a replacement movement.

I saw a movement in Australia (web site link I found here) and one in France (via Ebay). Is it possible they still exist? I've read they do not.

How difficult is a movement swap? It looks to the newb eye that the face, hands and etc will have to be moved over to new movement. 

When Seiko says the motor(s) are bad, do they mean the coil(s)?

None of the dials work but it does chime.

I'd really like to get my Moonphase back up and going. 

Any help would be so very much appreciated.



July 7, 2017 at 8:49 PM Flag Quote & Reply

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