Omega Tank Watch - Cal 684

[Latetothegame]

A friend of mine asked me if I could fix two vintage Omega watches.  One from 1954 and one from the 1970s I believe.  The older watch is a PX6553 with a cal 420 movement (I would love to know the model name if anyone knows).  The 420 needed a complete service and is now running great.  

[RichardHarris123]

Photos the dial and case please. 

Edited September 13 by RichardHarris123

[Latetothegame]

 The other watch is an Omega De Ville automatic tank watch (1970s I think).  This watch has a Cal  684 movement.   Once again my question is related to the case.  I have attached a group of pictures and I am hoping someone can tell me how to open the watch.  I have learned not to pry too much if I don’t find a notch to put a blade into.  I have read about Omega tank compressor cases that have some sort of pins holding them on but the dimensions of this case do not match  the dimensions of those cases.  The actual movement looks pretty straightforward .  Thanks for your help!

1 minute ago, RichardHarris123 said:

Phof the dial and case please. 

I’ll add pictures but the dial is not original to the watch.  It says “Automatic “ but the 420 is a manual wind.  The 420 movement is original to the case as it is listed as the movement used in PX 6553 models.  I was hoping the model number from the case would be enough.  I don’t have the watch any longer but here are some pics I took. Thanks.

[RichardHarris123]

Totally confused now, do you want to know the model of one watch or how to open the other?  

[Latetothegame]

2 hours ago, RichardHarris123 said:

Phof the dial and case please. 

I’ll add pictures but the dial is not original to the watch.  It says “Automatic “ but the 420 is a manual wind.  The 420 movement is original to the case as it is listed as the movement used in PX 6553 models.  I was hoping the model number from the case would be enough.  I don’t have the watch any longer but here are some pics I took. Thanks.

 

2 hours ago, RichardHarris123 said:

Totally confused now, do you want to know the model of one watch or how to open the other?  

Both, it’s a two parter.  I can see now I should have submitted two separate topics.  You answered part one before I finished asking the part two.  Sorry for the confusion.  

[JohnR725]

7 hours ago, RichardHarris123 said:

Totally confused now, do you want to know the model of one watch or how to open the other?  

sometimes this can be referred to as hijacking a discussion. Often times usually newbies who come to existing discussions and say my watches the same as and that's not really the way to do it as I would typically consider each watch a separate discussion.

then we throw in the other problem of the title versus the discussion itself. Titles need to reflect what the discussion is otherwise people will not necessarily participate in a discussion if the title does not reflect what the discussion is.

so this now brings up what exactly is the question kind of an yes it is very confusing

5 hours ago, Latetothegame said:

Both, it’s a two parter.  I can see now I should have submitted two separate topics.  You answered part one before I finished asking the part two.  Sorry for the confusion.

then I'm confused where they answer was but apparently it's been answered? just a clarification to Omega reference or case numbers? They're not always an exact science Frentzen some wobble watch will get a number and it could refer to quite a few different cases. In other words it could be stainless steel or solid gold or lots of things it's more like a style number than an exact something number. Then especially when you start C Diels changed often times people will assemble a watch to sell to some unsuspecting person and they will mix-and-match things that seem to fit in the case.

Then yes the other case I would definitely recommend not prying as that's not how the watch comes out. It be really nice if we had a number from anywhere? I don't suppose there is numbers at the end of the case if you remove the strap?

 

conveniently I cannot find a picture of what I'm looking for but I can speculate on what I'm finding there is supposed to be two separate spring clips that are used to hold the stainless steel part of the case in the rest of the case. So somehow you have to push them out in the absence of any other information from where their hiding in the image. Then the entire back assembly with the crown will come out. That's why you'll notice that the crown case tube is part of the stainless steel part holding the entire movement and not attached to the outer case itself.

 

[rehajm]

Here’s what looks like what John is looking for- you can see a spring/wedge piece sticking out the side that your pic doesn’t show? Either the wedge is removed and the movement lifts off the body or the case back should lift and slide, maybe towards the crown in order to release it from the main body. I don’t have a good look from the side but it looks like the case is thick enough so when sliding the back a bit it will clear the rotor…

Edited September 14 by rehajm

[Nucejoe]

Will you remove the strap, might find a release spring hidden between the lugs.

[Latetothegame]

As per the recommendations I removed the straps but there were no numbers between the lugs(see pics).  However, I did some more cleaning and tried a different camera angle and did find that there are two spring/wedge pieces inserted, one at each end of the stainless steel case back(see additional pics).   So, now I need to know how to get them out and remove the case back.  This is my first experience with this type of case.  Thanks for your help.  

[Nucejoe]

This gives you two sides to push on, to unlock/ release  the case back. 

First one , spring might slide out if you push on it in direction thats parralel to straps " spring bar"

Second , concievably pushing on the " spring / wedge" might move it out of a groove cut in case back.

Expectedly, cleaning around the srping/ wedge, might reveal more as it might be a 1mm thick spring and flex easy.

Rgds

5 hours ago, rehajm said:

Here’s what looks like what John is looking for- you can see a spring/wedge piece sticking out the side that your pic doesn’t show? Either the wedge is removed and the movement lifts off the body or the case back should lift and slide, maybe towards the crown in order to release it from the main body. I don’t have a good look from the side but it looks like the case is thick enough so when sliding the back a bit it will clear the rotor…

@rehajm 

Very reasonable and smart of you, to predict   probable ways this might be done. 

Edited September 14 by Nucejoe
Typo

[Latetothegame]

I did some additional cleaning and discovered that the bars actually run the full width of the watch case in the slot cut in the gold part of the case.  See red lines on pic.  It seems that maybe I should push on one end and push it entirely out the other side.  I placed a small screwdriver on the end closest to the crown side and tapped on it and  it did move a bit out towards the other side.  It doesn’t seem as if that could do any damage if I continue to push it through until I can grip it with pliers and pull it out the other side.  Am I missing anything?

Nucejoe, I just reread your comments and I think this is exactly what you are suggesting, correct?

Ok, got it!  Once again thank you to everyone for your help! 

[JohnR725]

notice how the whole thing came out as one unit including the crystal. thing is sandwich together to hold it in place there should be a gasket under the crystal or somewhere to make the whole thing water resistant. Therefore lucky once you get the movement out which? Now they came out as an entire unit it's probably considered a front loading watch and you'll have to pull the crown out to get the movement the come out. Then the entire movement should drop out the front side of the case back. Then when we finally get the inside of the case back there should be a reference number for future reference and for ordering parts like conceivably the gasket that's under the crystal.

 

 

 

[Latetothegame]

The back case came out with the movement still in side and the dial attached to the movement with a couple dial foot screws.  The gasket was actually attached to the dial face.  The crystal remained attached to the case front.  The movement has a two piece stem which I had to remove to get the movement out of the case back (as you had anticipated).  No matter how certain I am that the stem must be a two piece type I always get some anxiety as I pry just hard enough to either pop it off or break it if I’m wrong.  I was quite relieved when it popped off.  I did do my best to lift the edge of the dial to see if there was some sort of stem release.  When I couldn’t find one, I committed to prying it off.  What I found inside:  Serial # 35318324 (made in 1972,) Ref. # MD 156 0001,  Movement Cal.684.    The movement is tiny and fits inside my wedding ring.   See pics.  Again, thanks to all for your help.  As a group you have helped me resolve every problem that I have brought to the forum.  When I can’t find my answer anywhere else, I know I can get the answer here. 

Edited September 15 by Latetothegame
Typo

[JohnR725]

1 hour ago, Latetothegame said:

156 0001,

typically if you go to cousins website for documentation and search for the number 156 as is usually better to drop off all the other numbers we would find? but not this time we do get a tool of them stainless steel and whatever the other one is 156.0002 all attached the PDF probably may be? Then I also have the link below that has a couple of parts listed.

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=OME_CS^156.0001

1 hour ago, Latetothegame said:

No matter how certain I am that the stem must be a two piece type I always get some anxiety as I pry just hard enough to either pop it off or break it if I’m wrong.

typically with most watches and a watch like this the split stem will pop out. Some Omega watches from you take the crystal off you can see the locking ring you can even see where the split stem is. So you just move the locking rings the movement comes out and rotate and turn the movement over and the thing just pops out. Otherwise typically you can just split a split stem but I always like to urge caution for anyone doing mido watch as they most definitely do not pop out well they can win a watchmaker in the shop do that then he attempted to tighten the mess that he had and one year later we got all the bits and pieces to put the watch back together again. So yes it's always best to use some caution but typically on a split stem not like 99% of the time they will just pop apart

 

4723_Omega 156.0002 ST Case-1.pdf