Omega 861 Chronograph Hand Jumps When Chronograph Stopped

rbrimer · Sep 7, 2019

Hi all,

I have a Speedmaster Mark II. Runs well and keeps time. Chronograph starts, stops, and resets as it should. The issue I'm having is when the chronograph stops the chronograph hand jumps backwards anywhere from a fraction of a second up to 2 full seconds instead of just stopping dead. Not sure what the fix is. Initially I thought the hand might have been loose, but when it resets it's dead on 12 o'clock every time. Figured I would have issue with that too if a loose hand. Any and all help is appreciated!

henrikaa · Sep 7, 2019

A service might do the trick?

Archer · Sep 7, 2019

Returning past zero and then coming back to 12 is perfectly normal...

rbrimer · Sep 7, 2019

Thanks Al. Don't think I'm doing a good job describing the issue. I made a video that shows it beautifully, but I can't seem to upload it. Basically, when I turn the chronograph on it starts and runs great. If I stop the chronograph (not reset to 12) at say 17 seconds, the chronograph hand won't stop at 17 seconds, but hop back to the 15 or 16 second mark. It'll reset to 12 perfectly after that. Trying to figure out what's causing that hop back. Thanks again for the assistance.

Archer · Sep 8, 2019

Okay - I get what you are saying now. does this happen even if the watch is lying flat on the case back? Does iot get worse or better if the watch is in a different position?

So there are two things that happen when the chronograph is running, and you stop it. One is that the wheels that are driving the chronograph wheel (that the large central hand is attached to) disengage, so the wheel is no longer being driven. The second thing is that the brake swings in to hold the chronograph wheel in place.

Not being able to see what is happening, my guess is that possibly an adjustment needs to be made in the engagement of the teeth that are driving the chronograph wheel.

rbrimer · Sep 8, 2019

Thanks Al. It does do it flat on the case back. Haven't checked different positions to see if there's a difference. May have someone have a look if it bugs me to that point. Thanks again.

Omega 861 Chronograph Hand Jumps When Chronograph Stopped

rbrimer

henrikaa

Archer

rbrimer

Archer

rbrimer

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