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Swiss 7750 Omega Seamaster Chrono with mods


NaviChief

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This project was over a year in the making. Mostly because I didn't have the time, but also because I didn't have the skills to complete the work at first!

The story:

Sometime last year I bought a package of 2 busted watches from a member who had bought them from the original owner. They were a early SMP Chrono and an asian SMP GMT. Both were in parts. I received the SMP Chrono without the bezel insert glued down, fitted with the bezel ring from the asian GMT (previous owner did a good job with that), and with a busted asian 7750 (pallet jewel gone so the watch was unwinding without being timed). The problems came from the poorly made crown and stem that had messed up the keyless works and eventually probably caused the internal damage to the movement. Also, the first owner had bent the original bezel ring trying to remove it to properly seat the insert, hence the bezel transplant.

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After being quoted $750 by a local watchmaker to replace the balance and pallet fork and service the watch (OK he thought it was genuine Omega and I was too shocked to correct him), I picked up a 17 jewel valjoux 7750 of eBay for a song. Now, everyone should know by now that the hand sizes are different between the asian and swiss 7750. After unsuccessfully trying to modify (ie destroying) the center seconds hand, I bought a genuine hand from Ofrei. When trying to test fit everything together, I foolishly used the old stem and crown and popped the keyless works on my swiss 7750. At that point I took several months off to study watchmaking and buy some top notch tools. I recently went back and fixed the keyless works (hacking lever was out of place and jammed) and serviced everything on that side of the movement. It would have taken so much longer if it wasn't for The Zigmeister's beautiful and detailed pictorials of the 7750.

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Finally, I shortened the stem so it can be left unscrewed and still be close to the case. This relieved the pressure that was destroying the keyless works on both movements. I didn't expect it, but I can screw down the crown much easier if I wanted to, but I leave it out most of the time.

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That's my new toy! It was running 4 minutes fast a day when I first got it all together. I've regulated it down to 30 seconds slow, and will try a couple more times to narrow that down. I hope you enjoyed the pictures and story!

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Well done! I've got a SMP Chrono that can't be wound manually any longer and only holds about 8 hours worth from the rotor. After taking the back off the watch I realized that the 7750 is WAY out of my league. That you were able to teach yourself what you need to know to perform your own work is impressive!

SR

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Congrats man. The end result is what matters, and it turned out well.

Great watch. I absolutely love my SMP chrono as well. Maybe one day my watch will have a Swiss transplant too.

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Thanks everyone!

@SR....Thankfully I only had to break down the calender and bottom plates of the movement to get to the keyless works. The other side....forgetaboutit, I would leave that to The Zigmeister for now!

The hour chrono register did give me some problems though, I put everything together and during a timing check I noticed the hour subdial was running all the time! BAH! A reread of The Zigmeister's tutorial showed that I had left the part holding friction against the subdial gear without tension from a TINY spring. I had to take apart and rebuild (including re-oiling) everything twice! Good practice I guess....

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Great story...I am so glad you took the time to learn watchmaking, and get some watchmaking tools. It's great that you can do your own repairs, and if you can take the dial side of the movement apart, and get that blasted spring to stay in place, the rest is easy stuff...

Good on you for doing it yourself, congrats again on such a fine job. And I am glad that some of my posts were of use to you.

RG

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Thanks everyone!

@SR....Thankfully I only had to break down the calender and bottom plates of the movement to get to the keyless works. The other side....forgetaboutit, I would leave that to The Zigmeister for now!

The hour chrono register did give me some problems though, I put everything together and during a timing check I noticed the hour subdial was running all the time! BAH! A reread of The Zigmeister's tutorial showed that I had left the part holding friction against the subdial gear without tension from a TINY spring. I had to take apart and rebuild (including re-oiling) everything twice! Good practice I guess....

Don't sell yourself short. That 7750 is intimidating and the work you did isn't something just anyone could do. If I could get even as far as you did, I could probably venture into the movement further in an attempt to figure out what's wrong. But for now, this beast is out of my league!

Again, well done!

SR

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