2225.80/1164 "skipping" minutes?

ErichKeane
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Hi all-
I have a 2225.80 Seamaster Chronograph (1164 movement, so apparently just a 7750) that I noticed today "skips" minutes sometimes. It seems to happen ~1 in 4 times for the first minute, though I timed it missing 4 minutes out of the first 19 minutes (so showed 15 after 19 minutes) when I tested it earlier today.

This WAS serviced a little less than 2 years ago, but the watchmaker is both tough to get a hold of, and only does a 1 year warranty (or 6 months if he considers this "vintage"). So I don't suspect I'll get help there.

I HAVE done a small amount of watch servicing myself, so was wondering if this is a job for a professional, or if this is something I might be able to handle myself? I know there are a couple of 'cam' adjustments around the chrono, but it isn't clear to me which would need help.

I caught a video of it happening (https://photos.app.goo.gl/YsJ5sNdX8Mmr2oxF7) though it is too big to upload, despite only being 13 seconds. Basically: Chrono hand passes 12, but the minute hand doesn't budge.

It doesn't happen consistently (it took a few tries to get that on video!), but enough that my chronograph isn't really dependable for obvious reasons.
 
Canuck
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Unless you are prepared to mess up your exploration into adjusting your watch, resulting in major work, leave it alone! Not a watch to experiment with.
 
JimInOz
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ErichKeane ErichKeane
but it isn't clear to me which would need help.
PM later, have to have dinner now or else Ms JiO will grab me by my ear and lead me to the dining table.
 
Archer
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The first thing I would look at is the adjustment of the finger on the chronograph seconds wheel. The finger is what trips the advance of the minute counting wheel, via an intermediate wheel. In some cases the finger can be out of adjustment, like this one was:


The finger is adjusted (bent carefully) to have the tooth of the intermediate wheel first contact roughly in the middle of the flat part of the finger. The finger will then flip the minute counter, and will most likely contact the next tooth of the intermediate wheel. When it does so, it should only just take up the backlash between the intermediate wheels and not move the minute counter wheel again. It looks like this when properly adjusted:


Let us know what you see when you watch this area…

Al
 
ErichKeane
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Archer Archer
The first thing I would look at is the adjustment of the finger on the chronograph seconds wheel. The finger is what trips the advance of the minute counting wheel, via an intermediate wheel. In some cases the finger can be out of adjustment, like this one was:


The finger is adjusted (bent carefully) to have the tooth of the intermediate wheel first contact roughly in the middle of the flat part of the finger. The finger will then flip the minute counter, and will most likely contact the next tooth of the intermediate wheel. When it does so, it should only just take up the backlash between the intermediate wheels and not move the minute counter wheel again. It looks like this when properly adjusted:


Let us know what you see when you watch this area…

Al
Awesome, thanks for the videos! I'll have to take a look. I was hoping it was a cam-screw type adjustment and not a 'bend small wires' type adjustment (I'm still 0-for-everything on hairsprings), so I might see if I can pick up a clone 7750 movement (though I have a ST19 chronograph on my 'to disassemble' list, does this have a similar adjustment?) to use as practice before I dive into this one.
 
Archer
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ErichKeane ErichKeane
Awesome, thanks for the videos! I'll have to take a look. I was hoping it was a cam-screw type adjustment and not a 'bend small wires' type adjustment (I'm still 0-for-everything on hairsprings), so I might see if I can pick up a clone 7750 movement (though I have a ST19 chronograph on my 'to disassemble' list, does this have a similar adjustment?) to use as practice before I dive into this one.
Sorry, I don’t work on clones so I can’t say for sure. If it really is a 7750 copy it should be the same.
 
ErichKeane
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Archer Archer
Sorry, I don’t work on clones so I can’t say for sure. If it really is a 7750 copy it should be the same.
Oh of course that makes sense. The ST19 is based on a Venus 175 I think. There are definitely some chinese 7750 clones that are at least physically identical, if performance wise, much worse. BUT screwing up a $100 junk movement is a lot less concerning for practice than the real thing.
 
ErichKeane
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As an update, a few things happened 😀

I was planning on fixing this myself, but not without some practice! I ordered some 'not working' 7750s on aliexpress, which showed up today (though ended up being some weird Invicta Daytona clone variant) to use as practice/figure out what I would be looking at before taking apart my seamaster.

AFTER I ordered those though, my watchmaker actually responded, and said to send it in and he'd fix it! I'm outside of warranty, but he is doing it for nothing anyway, and did it without putting me in his queue, so it happened quickly. As we all suspected, it is the minute-jumper-finger, which was easy enough to fix apparently.

The watch is currently on its way back (or on its way to being on its way back!), so it'll get to spend time on my wrist again!

AND, I also get a pair of junk 7750 descendant/clones to screw up as even further practice before I get to the Landerons I want to fix. SO, an overall positive outcome in multiple ways!
 
Archer
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Good - it really is a quick adjustment for any competent watchmaker so would only take a few minutes.

I’m not sure if this was new behaviour long after the last service, but this is a standard check that should be done on every one of these that is serviced, so if it came from the watchmaker this way, he should fix it anyway.
 
ErichKeane
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Archer Archer
Good - it really is a quick adjustment for any competent watchmaker so would only take a few minutes.

I’m not sure if this was new behaviour long after the last service, but this is a standard check that should be done on every one of these that is serviced, so if it came from the watchmaker this way, he should fix it anyway.
I never noticed it previously? I use the chronographs pretty frequently, so I would have expected to notice it, though dropping a minute here or there perhaps wouldn't be horribly noticed.

BUT this got up to ~4 minutes in a short amount of time, so I started noticing it. It IS a 'beater' watch (the one I wear when I am going to do things that I would be worried about wearing something else) for me, so I could have bumped it on something? Or, just unlucky.

Either way, he apparently agreed with you and turned it around really quickly and shipped it back! I'll have it early in the week.
 
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