wtchgk Posted August 1, 2011 Report Share Posted August 1, 2011 I have encountered the following problem on more than one A7750. The chrono stops when activated and stops the movement with it. Shaking the watch sometimes gets everything moving again, but then it stops again around the point where the minute counter is advanced. If I loosen the screws of the automatic device bridge a bit the chronograph works fine. (Obviously, operating any buttons in this state would risk jamming the chronograph mechanism and possibly damaging delicate parts.) I wonder if especially the watchsmiths have found whether there is a single culprit that is mostly causing this. Quote Link to comment Share on other sites More sharing options...
sander Posted August 2, 2011 Report Share Posted August 2, 2011 I have encountered the following problem on more than one A7750. The chrono stops when activated and stops the movement with it. Shaking the watch sometimes gets everything moving again, but then it stops again around the point where the minute counter is advanced. If I loosen the screws of the automatic device bridge a bit the chronograph works fine. (Obviously, operating any buttons in this state would risk jamming the chronograph mechanism and possibly damaging delicate parts.) I wonder if especially the watchsmiths have found whether there is a single culprit that is mostly causing this. Dirt! get it serviced.... Quote Link to comment Share on other sites More sharing options...
FxrAndy Posted August 2, 2011 Report Share Posted August 2, 2011 and the exenctric adjuster for the colum wheel is set a bit too tight possibly Quote Link to comment Share on other sites More sharing options...
Rolexman Posted August 2, 2011 Report Share Posted August 2, 2011 Or not enough power is generated due to faulty main spring or dirty gear train... Quote Link to comment Share on other sites More sharing options...
wtchgk Posted August 3, 2011 Author Report Share Posted August 3, 2011 Thank you very much for your replies. I am well aware that a service will mostly likely solve the problem, but I am really curious about possible failure mechanisms aside from dirt and improper lubrication. In case you want to know, I eliminated the column wheel (oszillating pinion) and clutch as the cause. So it seems that maybe not enough power is being generated and/or there is too much chronograph wheel friction. The parts driven by the chronograph wheel move freely. I do have a feeling that the main spring is contributing because I can wind it for a long time without ever feeling strong resistance. However, you may also be interested in hearing what triggered all this in the first place. By now I received several watches that either were DOA or only partially working. All came from trusted dealers that claim to do good QA and I am reasonably confident that besides sending pics they test at least all functions of the watches before they ship. So what happens during transit that causes these watches to fail? In one case I found that a moving and a non-moving part were 'baked' together and stopping the watch. My best guess is that this was caused by exposure to extreme heat (120+F/50C) during transit in the Southwest US. Quote Link to comment Share on other sites More sharing options...
Rolexman Posted August 3, 2011 Report Share Posted August 3, 2011 Best thing you have it looked at by a local watchsmith. Quote Link to comment Share on other sites More sharing options...
sander Posted August 3, 2011 Report Share Posted August 3, 2011 It takes hours and hours of testing to solve problems like this. Best and cheapest way is to get it overhauled. It takes a few hours but then at least ALL the parts can be checked, cleaned and properly lubed. Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted August 4, 2011 Report Share Posted August 4, 2011 Bent pivots on the tilting pinion will create the issue you are having as well. One more thing that needs to be checked. Quote Link to comment Share on other sites More sharing options...
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