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Forum Home > Parts Info, Tech Tips and Tinkering > Problems with stem and resetting chrono' hands

Sahderach
Member
Posts: 3

Hello all!

I actually have 2 problems regarding the stem that I hope you folks have experienced before.

Both problems occurred as I was playing with my "learning" 7a38 movement and had the stem removed (which I did properly and with no incident).

First problem:

I went to put the stem back in and since I've only messed around with it a few times I was very careful not to force it but it was hanging up going back in. Carefully repositioning the movement ever-so-slightly enabled me to get it pushed all the way in but once I pulled it out to test the positions and it came right out, without pressing the release. I pushed it in and pulled it out gently a few times and eventually it "caught" and all functions operated as normal.

Is this normal? Is there a technique I should use in the future to seat the stem properly the first time?

Second problem: 

This time, I went to put the stem back in, and as above, it was very difficult to seat properly. I eventually got it in but went to do an operational test and discovered that when pulling out to the first position, I cannot adjust the chrono hands. The chrono functions operate as if the stem is pushed all the way in. Basically I cannot recalibrate the chrono hands at all. I can adjust the day and date as normal in this position but not the chrono hands.

Anyone seen this before and could point me in the right direction?

Thanks in advance!

October 10, 2013 at 5:44 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 14136

I can't say I've ever personally encountered this problem, but I suspect you may have been a little too forceful pushing the crown / stem back in one time and bent something. The proper way to re-insert the stem would be to hold down the little dimpled release lever, as you would when withdrawing it. Like most of us, I never bother myself - just ease it back in, rotating the crown as neccessary - by feel.


I presume you've read the couple of excellent topics started by Simon (Sir Alan) in the other Workshop sub-section ?


http://www.seiko7a38.com/apps/forums/topics/show/7517616-inside-the-7a38

Note this part:


Here's a closeup of the tiny gold plated regulator (the 0.26 second per day adjustment), and also something that I'd not paid any attention to before, the tiny little arm that makes contact with the circuit to tell the cpu at which position the crown is:




I've read some very informative posts by DaveS referring to this not making contact properly and causing problems.


See page 7 of the 7A38A Technical Guide: http://service.seiko.com.au/i/seiko/documents/technicalguides/7A38A.pdf

and page 10 of the 7A28A Technical Guide: http://service.seiko.com.au/i/seiko/documents/technicalguides/7A28A.pdf


More photos of the crown release / setting lever further down this thread:

http://www.seiko7a38.com/apps/forums/topics/show/7709682-we-re-going-in-deep-inside-the-7axx


October 11, 2013 at 1:20 AM Flag Quote & Reply

Sahderach
Member
Posts: 3

Excellent! Thanks so much for the response. I'll get looking!

October 11, 2013 at 2:29 PM Flag Quote & Reply

Sahderach
Member
Posts: 3

That was it! I must have bent it down while probing for the release catch for the stem. All I had to do was gently bend it back up into position. Lesson learned!

Thanks again for the help, love the site!

October 11, 2013 at 3:02 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 14136

We try to please. :D

October 11, 2013 at 3:19 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 14136

It appears we should also heed our own advice sometimes. :roll: Of more anon.* ;)


I've edited the OP's original topic title slightly so it may serve better as a pointer for other readers who encounter similar problems.


Here's a screen print of the relevant section of page 7 of the 7A28A Technical Guide:



*See my last couple of posts in this thread - where I failed to spot a bent setting lever arm during a partial movement re-build. :roll:


October 27, 2013 at 9:51 AM Flag Quote & Reply

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