rionrlty Posted June 11, 2013 Report Share Posted June 11, 2013 Hi guys and girls, I've been on the forum for several months now and am enjoying myself, but I have run into a curious problem. I recently purchased a Breitling Blackbird from another forum member. It is the older model with the date that goes all the way to 39 before turning to 00 and then 01. I also recently bought a 4 position watch winder and rotate 8 of my watches on it. My research told me that the A7750 movement, which the Blackbird is powered by, was unidirectional and typically wound in a clockwise rotation, so I set it up that way on the winder. I found it curious that when I would take the Blackbird off of the winder that it was often run down. None of my other watches with the A7750 seemed to have this problem. On a whim I decided to reverse the rotation and Voila! This seemed to fix the problem! Does anyone know why this particular watch with the A7750 movement would wind in the opposite direction to the others? Also, I am having a problem with the date change. For two complete monthly cycles of the date mechanism it will both skip dates unexpectedly and also sometimes skip ahead by 10 days like from 00 to 10, or 15 to 25. Then, on the third cycle will change correctly. Does anyone know if this is a common problem or how to fix it. Thanks in advance for any advice on this. rionrlty Quote Link to comment Share on other sites More sharing options...
Rolexman Posted June 11, 2013 Report Share Posted June 11, 2013 I recently had a Big Date on the work bench and the gear ratio is very tricky. The date should run from 01 to 31 and start again from 01. Someone probably already worked on your watch and didn't know what he was doing or it happened in China.... To adjust it you need to strip it down and adjust the interconnection of the gears and date wheels. Quote Link to comment Share on other sites More sharing options...
FxrAndy Posted June 11, 2013 Report Share Posted June 11, 2013 If it goes to 39 it may not be a 7750 but an a21j ( but I have never seen a BB like that) But is it is a 7750 (working chronos) and it goes to 39 then you are in a world of pain trying to get the date right. I remember doing it on mine years ago and you need a degree in algebra or a lot of time 1 Quote Link to comment Share on other sites More sharing options...
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