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Adventures in Servicing a Gen Omega Seamaster 1120

hanski

Renowned Member
25/4/18
824
501
0
After having serviced 3 genuine vintage Tudor movements, a couple Sellita’s, and numerous Asian clones, I’ve decided to embark on the journey to service a genuine Omega 1120 for a Seamaster.

Received the watch, looks good albeit clearly worn and loved.


VWWrkU.jpg


I give it a full wind, set the date, set the time, and...nothing. It’s not ticking. Some more winding, some gentle shakes...nothing. I flip it upside down...there it goes. Hmm, this doesn’t bode well. But I’ll reserve judgement until it’s been torn down and cleaned.

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On to removing the bracelet, caseback, and dust cover.
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Looks pretty clean except the stem is fully rusted and the movement ring is rusted in to place. I hope not to discover anything bad when I get the dial off.

Off comes the automatic works and rotor together since the rotor screws are on the underside of the automatic works.


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Now to remove the movement, take off the hands, and dismount the dial. It takes a bit of careful effort but the rusted movement ring releases. Hands are set to be stacked, protective Mylar cover over the dial to protect dial, Saran Wrap over hands to protect finish on hands. I like to use the pry bars in lieu of the hand removing tool, I have more control.


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Next I flip the movement back over and remove the balance, gear train c0ck, and barrel bridge.

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Back to the top side. Thankfully no further rust or corrosion has presented itself. Off comes the date wheel, calendar works, wheels, pinions, and finish up with the keyless works.


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Main plate stripped. Automatic works and barrel bridge stripped down. Everything is neatly organized and ready for a four stage ultrasonic cleaning and rinse. And then it’ll all come back together with a bit of oil.


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Since the balance wheel, pinion, and jewels look to be in fine shape I hope the lack of consistent movement is simply grime and age.

Stay tuned.
 

mydnytrydr

Mythical Poster
25/9/09
7,800
219
63
Do you think the water got inside the watch because of a bad seal or the crown wasn't closed all the way? ..
 

hanski

Renowned Member
25/4/18
824
501
0
Do you think the water got inside the watch because of a bad seal or the crown wasn't closed all the way?
Good question! Honestly I don’t know. If I had to guess based on the condition of the watch and crown, I’d suspect worn gaskets and possibly damage. The crown does have a large chunk of the plating broken off. Also, the rust and corrosion isn’t extensive, it’s fairly limited to the stem and movement ring at the stem. This indicates to me only small amounts of moisture entered from the crown location.
 

hanski

Renowned Member
25/4/18
824
501
0
Cleaned and ready for reassembly - mostly.

After four ultrasonic bathes (1 cleaner and 3 rinses) all the parts were heat dried and organized, inspected, and prepared for reassembly. Also decided to demagnetized for good measure.


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Balance wheel and bridge got a One Dip bath instead.

Upon inspecting the balance wheel I noticed the Hairspring had a bit of a kink and was touching. Maybe this explains some of the issues it was having earlier.


VzmwrD.jpg


If you look closely you can see the pin kinks in towards the center and is crooked.

Anyways, I think most normal people would opt to buy a new balance wheel for $50. Not me! I decided to attempt to reshape the Hairspring.

No easy feat, I will admit. First the Hairspring must be removed from the wheel - a pair of pry bars work well. It’s very similar to removing a hand set but smaller and more fragile. This was done without issue.

Next on to reshaping the Hairspring. Using two pair of tweezers, one must incrementally, patiently, and carefully grab the spring where it is out of shape and basically massage it back to position. To confirm my reshaping I would lay the Hairspring centered on the bridge, frequently.

 Fast forward about 60 minutes and I have a center, flat, and well shaped Hairspring. Yay!


Last step is to press the Hairspring collar back on to the balance wheel. Pro tip, remember to mark the orientation of the spring before removing so it can be replaced correctly. Well, I wish I were ending this story with a pretty picture of a balance wheel complete...but I’m not. In pressing the collar something moved and pinched the spring. I don’t think I’m going to be able to reshape it this time.

Lesson learned, just buy the balance wheel complete and install it!
 

hanski

Renowned Member
25/4/18
824
501
0
While I’m waiting on some parts, good progress was made in the lubricating and reassembly of the movement. On order is a new balance wheel complete, stem, and crown.


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Barrel bridge with integrated click comes together nicely.

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Installed on to the main plate with the drive train.

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Keyless works installed using the old stem.
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Pallet fork back on. Tested for distribution to the fork, flicks back and forth nicely.

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Automatic works.

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Rotor screwed back on. Notice this one is screwed in from the underside. When doing anything to this movement, the whole automatic works needs to come off with the rotor attached. Not particularly convenient.

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Date wheel, date jump, and pinnions installed.

Look forward to getting the parts and regulating the movement.
 
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hanski

Renowned Member
25/4/18
824
501
0
New ETA chronograph grade balance Complete arrived. Looks pretty!

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Simple installation. I chose to install the balance wheel and balance bridge before connecting them together. This allow me to properly align the parts and free up hands to make the connection.
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Movement full reassembled.
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Dial and hand set reinstalled.
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Re-cased.
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Final step is to regulate on a full wind and test the timing over the next couple days. I was able to bring the beat error to 0.0ms and face up timing to +3sec. Pretty good. But I didn’t continue because the amplitude was very low - 150-175. Not a good sign for the mainspring. I am ordering a new mainspring to install.

Almost there.
 
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unreformed66

Known Member
Supporter
7/11/15
165
19
18
United States, Ohio
The mainsprings in these usually don't go bad unless the bridle breaks off. Did you remove the mainspring from the barrel and clean it? If so what did you lubricate it with when you put it back together? I notice that in the pictures that the barrel is unopened. Did you remove the balance jewels? I'm not seeing them laid out with the rest of your parts in the disassembly picture. If you did those two things and the amplitude is still low it could possibly be a mainspring problem but that's not where I would look first. That's providing that the movement is actually as clean as it needs to be and that all the pinions and wheels are in good shape.
 

hanski

Renowned Member
25/4/18
824
501
0
The mainsprings in these usually don't go bad unless the bridle breaks off. Did you remove the mainspring from the barrel and clean it? If so what did you lubricate it with when you put it back together? I notice that in the pictures that the barrel is unopened. Did you remove the balance jewels? I'm not seeing them laid out with the rest of your parts in the disassembly picture. If you did those two things and the amplitude is still low it could possibly be a mainspring problem but that's not where I would look first. That's providing that the movement is actually as clean as it needs to be and that all the pinions and wheels are in good shape.

Thanks! All really good points. Here’s where I’m at with things:
- Cap jewels had been cleaned and lubricated. Decided to reinspect, reclean, relube, and check end shake.
- Reset balance wheel - noticed the pallet fork was magetnized. Not sure how it happened but this prompted me to recheck and demagnetized the movement and parts. Found one other screw in oscillating weight to be magnetized.
- Reinspected the wheels and pinions, along with their associated jewels. Also measured the endshake. Everything looks good.
- Piece by piece I tested and inspected the power transfer through the drive train. Things look good and once I get to pallet fork, the flick is clean, Swift, and responsive.
- After a thorough inspection, some recleaning for good measure, and demagnetizing I’m at the same point - consistent amplitude of 175, beat error of 0, and -2sec/day.
- RE: Mainspring - unfortunately I have not invested in a mainspring winder. With a complete new, ETA barrel and mainspring costing only $28 I’m going to install a new one rather than buy $$$ winder. After 10 cleanings, sure, it pays for itself. But, it’s cool, I’ll get there eventually.
 

unreformed66

Known Member
Supporter
7/11/15
165
19
18
United States, Ohio
Did you check the train freedom before you put the pallet fork in the movement? This is something that I always do just as soon as the train wheels are in, I test the endshakes and then test how freely they spin. Then after the mainspring and winding parts are in I wind the mainspring just a little bit and watch the train wheels. If they "recoil" and go the opposite direction once they've exhausted the power of the mainspring then that's a pretty good indication that everything is free and engaging properly. If you wind it slightly and the train is seen to go slower and slower until it just stops then you've got issues. Either something isn't clean or something is binding. Then the detective work can begin..lol. If you did not remove and clean the mainspring then your issue might lie there. Old gummy grease and dirt will cause the coils to stick together robbing the spring of it's power. Good luck with it.
 
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hanski

Renowned Member
25/4/18
824
501
0
Mainspring arrived - simple enough to swap it out. Gave it a full wind and put on the timegrapher.......viola!

+2sec, 0.0ms beat error, and amplitude up to normal.

In addition to the mainspring, the new stem and crown arrived. Another easy swap.

Project complete! Simply a delight to work on a gen watch like this.

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hanski

Renowned Member
25/4/18
824
501
0
Well I'm glad it turned out to be that simple. You say the amplitude is now "normal". What numbers are you getting?

Bit below 280. I would have liked to see 300 but with an acceptable range of 220 min to 315 max and the jump from 175 I’m okay with it