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Seiko 4205(A) Stripdown

Davey57

By Davey57
in Your Walkthroughs and Techniques

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  • 2 years later...
Davey57 WRT Addict

Davey57

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Hi

To be honest I never changed a crystal in any of mine. I found it was so easy to break the crystal retaining ring, that’s if it’s not already broken, that I mostly polished up the original crystal in situ.  It take a long time but can be done. I remember one that I did was in such a bad state I replaced it with a domed acrylic one and it looked quite good. Obviously it’s not going to be waterproof but I just wore mine for casual wear.  

Good luck with the watch!

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  • 3 years later...
DFKG Member

DFKG

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On 2/1/2016 at 9:12 PM, Davey57 said:

Flipping it over and the three train bridge retaining screws are removed. One of them holds a small friction spring in contact with the centre seconds pinion, meant to show that sorry.

post-923-0-00583100-1454360231_thumb.jpg

 

Lift the bridge clear but watch out for the transmission wheel pinion that is left behind. It can stick to the underside of the bridge and drop out when you aren’t looking, the small intermediate wheel next to it in the black box is also free to fall off. I am beginning to think that instead of removing the left handed screw and removing the transmission wheel you could leave it attached and then there would be no danger of losing the pinion below it. Removing the pawl lever as described above would still allow the mainspring to be wound down. In 4205B movements this is one unit anyway so not to worry.

post-923-0-22658200-1454360337_thumb.jpg

 

Barrel,train wheels and the centre seconds pinion are next. Then the pallet bridge and fork.

post-923-0-22897600-1454360397_thumb.jpg

 

At the beginning I mentioned that sometimes the winding mechanism might not feel right, you might get a few turns of the crown and then it goes loose then winds again.

Given the age of these things by now there must be considerable wear and some of the gears in the winding mechanism are well worn

I found that the winding pinion on the stem was not contacting the sliding crown on the winding bridge very well, it was tending to lie to one side and flop about. So what I did was to bend the spring that you can see inside the black box so that it puts more tension on the sliding crown and it seemed to keep things engaged a bit more positively. It’s easier to do this once spring has been removed.

post-923-0-09175300-1454360463_thumb.jpg

 

Take off the winding bridge and it’s almost there.

post-923-0-08025500-1454360513_thumb.jpg

 

Remove the centre wheel bridge and take out the escape wheel.

post-923-0-44930800-1454360555_thumb.jpg

 

Pull off the cannon pinion and remove the centre wheel.

post-923-0-77562200-1454360598_thumb.jpg

 

The barrel and spring.

post-923-0-12686700-1454360639_thumb.jpg

 

And the spring is removed.

post-923-0-04575900-1454360680_thumb.jpg

 

All the parts ready for cleaning.

post-923-0-20355400-1454360715_thumb.jpg

 

And that's it. Once everything is cleaned and ready, reassembly is just the reverse procedure.

I will be quite happy to post the pictures of it going back together if you wish.

Either way I hope it has been of help and that I have made things easy to understand.

It’s difficult to know exactly how much detail to include or omit. If anything is unclear or just plain wrong please let me know and I will try to explain things or make some edits to the post.

 

 

 

Hello, great walk through. I am at the moment stripping down this movement. 4205-0155... As when I lifted the oscillating weight plate up the Pawl Lever dropped on the floor! But I'm now a little unsure how it goes back? Obviously the small post under the bearing slots in to the jewel, but does it then just butt up against the end of the Sweep second hand friction spring which sits just under the Pawl lever covering the centre hole. I'm a little stumped over that little assembly!!!! Any help would b greatly appreciated. 

 This is also my first Automatic movement! I'm not completely green as I've done other movements but never Auto...

 Many thanks,

              David...

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bklake WRT Addict

bklake

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Download the technical guide for the NH05, it is much clearer than the 4205 guide.  The movements are the same.  The NH05 is produced by Time Module Inc, a branch of Seiko.  This link should work: https://www.timemodule.com/en/product-and-download.php?ds_product=2

Keep both guides on your bench, there are some minor changes as the movement has been updated a little. 

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DFKG Member

DFKG

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Hello, excellent walk through... But I need a little help!!!

 At the moment I've got the same 4205-0155 movement stripped down but I'm struggling to get the lid off the mainspring barrel!!!! Is there something unusual that I need to do. I've tried putting it on hard surface & pushing down gently on the teeth but nothing! There is no recess to put a tool to gently lever it off! Any help would be appreciated. It's such a small and dainty barrel that I'm scared to push too hard!

 Hopefully hear something soon.

Many thanks....

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gbyleveldt WRT Addict

gbyleveldt

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2 hours ago, DFKG said:

Hello, excellent walk through... But I need a little help!!!

 At the moment I've got the same 4205-0155 movement stripped down but I'm struggling to get the lid off the mainspring barrel!!!! Is there something unusual that I need to do. I've tried putting it on hard surface & pushing down gently on the teeth but nothing! There is no recess to put a tool to gently lever it off! Any help would be appreciated. It's such a small and dainty barrel that I'm scared to push too hard!

 Hopefully hear something soon.

Many thanks....

They’re not really meant to be taken apart so Seiko doesn’t make it easy to do so. But you can with patience and a scalpel, by gently pushing it along the very thin line where the top and bottom meet and separating it that way. It takes patience though. I’ll just quote a video of mine; it’s around the half way mark:

https://youtu.be/yrhYjLaoQvM
 

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