Junghans J880.1 (ETA 7750) Date Mechanism Question

[dscottd]

Well, I'm an idiot. I got a brand new Junghans Meister Chronoscope with modified ETA 7750 movement, and I was excited to try it on. It was about 9:30-9:45PM (you might already see where this is going) and I blindly went through my usual routine of winding, then setting the time to find the date changeover, then setting day/date. Of course, I usually do this at about 7:30AM.

Changing the day first, there was nothing out of the ordinary, so nothing caught my attention. Guessing the actuator teeth are timed just slightly differently, so apparently no contact was made here.

Then, changing the date, I noticed the hour and minute hands jitter slightly. I knew right away what I had done. I didn't realize the "no date change" zone was so large (8PM-2AM). In my mind, it was more like 11PM-1AM. There was not any resistance to be felt, but the date alignment was off slightly, and after I stopped and re-set the time, the next changeover did not advance the date (it did advance the day). After that, though, the date went back into alignment and was actuated as expected from then on.

I'm pretty sure I understand what happened, but just wanting some expert advice to put my mind at ease. I am assuming the actuator was just barely in the path of the date wheel teeth at 9:45, which explains the slight jitter in the hands but no resistance felt. Is it possible I could have knocked any springs or anything out of normal alignment, or caused any other damage? Is breaking off the actuator lever by cranking through when resistance is felt the only concern in this instance? Everything is working as expected now, as I said.

Thanks.

[nevenbekriev]

If everything is working, don't worry and enjoy You new beautiful watch. Everything is OK.

[dscottd]

3 minutes ago, nevenbekriev said:

If everything is working, don't worry and enjoy You new beautiful watch. Everything is OK.

OK, thank you. I figured as much, but as I was searching around, some were saying the 7750 date mechanism can be temperamental.

Thanks!

[Razz]

Doing a normal hand setting advancing of the day date should be ok at any time of day. It's the quick set function of the day date that should not be done during the 8 pm to 2am time frame, I think.  So I always advance to 5 or 6 before quick setting, then advance the hands normally once the day date is correct to the PM times if doing it in the evening.

Edited November 27, 2024 by Razz