imajedi Posted May 24, 2012 Report Share Posted May 24, 2012 I have an A7750 with a busted Chrono in my Ebel 1911. Everything else seems to be working fine. Is that a repare or just replace the movement? I've heard that the A7750 can be had for $50 bucks. Can anyone direct me to where those are because I couldn't find one on the bay. What about putting an authentic 7750 in it? I found one on ebay for $450 but it's coming from Switzerland. Isn't there something closer? (I'm in LA) I've read posts in here that have said the A7750 is just as good as the Gen if you get one that's put together without pieces of food and other contaminents in it. I guess therein lies the rub. Qualifications: No watch experience but 10 years as an engineer. Basically, I'm very comfortable with mechanical stuff. Plus I'm not sure how I could make things worse considering it's already broken. Quote Link to comment Share on other sites More sharing options...
tomhorn Posted May 24, 2012 Report Share Posted May 24, 2012 You have four choices (in order of likely cost): 1) Purchase another A7750 and swap it. 2) Service the existing movement 3) Buy a new watch. 4) Purchase an ETA 7750 and swap it. This order assumes you can do the movement swap yourself. Personally, I would take option #2 and get your current movement serviced. The A7750 is a great movement once serviced. It comes from the factory a little dry normally, which can cause issues. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 24, 2012 Author Report Share Posted May 24, 2012 Thanks, can anyone suggest someone who can service it in the LA area? Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 25, 2012 Author Report Share Posted May 25, 2012 Looks like I'll be servicing it myself. Might as well dive in head first. Here we go!!! Quote Link to comment Share on other sites More sharing options...
chronoluvvv Posted May 25, 2012 Report Share Posted May 25, 2012 Looks like I'll be servicing it myself. Might as well dive in head first. Here we go!!! how far are you from downtown ? Quote Link to comment Share on other sites More sharing options...
andreww Posted May 25, 2012 Report Share Posted May 25, 2012 Give your head a shake, you can't service it yourself. Requires years of experience and lots of specialized equipment to service a 7750. Quote Link to comment Share on other sites More sharing options...
kbh Posted May 25, 2012 Report Share Posted May 25, 2012 http://www.clswatch.info/CLS/services.html CLS in Pasadena is quite good with chrono movements. He's in Pasadena. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 25, 2012 Author Report Share Posted May 25, 2012 You're right, I'm sure I'll fail miserably but it couldn't hurt to open up the back and have a look around. I mean really this is a hobby and I think all of us want to learn more about the watches and movements and not just collect stuff. I'm never going to get anywhere close to being on par with the people here if I don't try. What better place to start than with a broken watch. But thanks so much for the references guys. I'll need them to actually fix the watch after I get done messing around. Cheers everyone. Quote Link to comment Share on other sites More sharing options...
chronoluvvv Posted May 25, 2012 Report Share Posted May 25, 2012 please tape your adventures for us to enjoy Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 25, 2012 Author Report Share Posted May 25, 2012 I will do my best to document both the successes and the failures for everyone's enjoyment. Quote Link to comment Share on other sites More sharing options...
slask111 Posted May 25, 2012 Report Share Posted May 25, 2012 Love the attitude :-) good luck with this, pls let us know how it turns out. Me, i would send the watch to a trusted modder. Wouldnt dare destroy my beloved 1911 ;-) Skickat från min GT-I9100 via Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 25, 2012 Author Report Share Posted May 25, 2012 Thanks, I won't destroy it. The only thing I can break is the movement, which is already broken. I ordered some tools on the bay and an oiler. I'll give everyone an update when the tools arrive and I dive in. Quote Link to comment Share on other sites More sharing options...
zzipy Posted May 25, 2012 Report Share Posted May 25, 2012 Can a A7750 be replaced with ETA 7750 without any issue of hands? I had heard that the hands might not fit from Asian to Swiss. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 26, 2012 Author Report Share Posted May 26, 2012 Is the post or hole to big. If the post is too big it seems you could just very carefully make the hole on the Asian hands bigger. Quote Link to comment Share on other sites More sharing options...
zzipy Posted May 26, 2012 Report Share Posted May 26, 2012 what if the hole is too big? Quote Link to comment Share on other sites More sharing options...
tomhorn Posted May 26, 2012 Report Share Posted May 26, 2012 The A7750 is not a movement that should be attempted to be serviced by anyone just starting out working on movements. To take this movement apart, clean it, replace any worn parts and reassemble with the proper oils is not something that can be done properly by anyone on a whim. I'm all for 'going under the hood and looking around' but if you truly want to learn how to service a movement, you'd be better off starting with a 6497. The hands can be broached when too small, or crimped when too large. Again something that should be done by someone who has experience in doing it. Getting replacement hands for the Asain movements once you've ruined a set can be problematic, if not impossible. The other option is to try to find gen hands for the 7750 based reps. They will normally fit without modifications. Also, if your rep originally came with the older style A7750 then they will also fit without modding. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 26, 2012 Author Report Share Posted May 26, 2012 Tom, I completely agree but the point is it's broken. I'm not gonna break it more. It's like making your girlfriend more pregnant. Here's the symptoms for anyone with any ideas. From the beginning the Chron hr. hand would always run even when the Chron wasn't working. However, the hr hand would also always get stuck at 3 either with or without Chron engaged. After playing with the Chron a few times it just stopped working all together. I reset it and the main second hand went to 11 instead of 12 and would no longer move forward. On top of that when the Chron is engaged now it brings the entire watch to a grinding hault. I can see the little heartbeat slow down and eventually stop (I have the back off) it's like something is stuck.... As soon as a press the button again to stop the chrono the watch begins to run again. The clutching mechanism for the chrono seems to be working ok as is the release. Quote Link to comment Share on other sites More sharing options...
tomhorn Posted May 26, 2012 Report Share Posted May 26, 2012 Tom, I completely agree but the point is it's broken. I'm not gonna break it more. It's like making your girlfriend more pregnant. Not entirely true. You could damage the movement to the point where it can't be fixed, or it would be cost prohibitive to do so. Then you'd need to buy a new movement, and probably want get it serviced anyway just to be safe. Then you're paying double, so imagine your girlfriend has twins. If you had done some movement work previously, I'd say go for it. The 7750 just isn't the starter project IMO. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 26, 2012 Author Report Share Posted May 26, 2012 Hahaha Re: Twins. I laughed out loud. Ok well call it a learning experience then which will at most cost me $200. I was looking at $150 anyway. So anyway, I removed the automatic device bridge and a bunch of [censored] came out. The good news is that what ever was making the chrono stick is no longer sticking. I can start and stop the chrono without the watch stopping. My thought is that if I can just get these parts back in there the right way it may actually work. These parts are so incredibly tiny, I had no idea. The one I really need help with right now is the oscillating pinion. From what I can tell this was likely the problem as it appears it connects the chrono seconds hand to the continuous seconds hand. The problem is it's a short shaft with a small gear at each end. The gears are different thicknesses and I don't want to put it in upside down. Anyone know which gear goes down, the thick or thin? I also need to figure out how to release the main spring on this thing because this little guy is not going back in while it's ticking. LoL Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 26, 2012 Author Report Share Posted May 26, 2012 For ref. if you look close you can see it. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 27, 2012 Author Report Share Posted May 27, 2012 I thought I may have accidentally fixed the problem but something is still amiss. The hr hand still runs and gets stuck at 3 even with the plate removed and both the chrono second and min hand completely free wheeling. You would think those were somehow tied together but apparently on the 7750 they are not. The hr hand of the chrono is being driven independent of the sec and min hand. Anyone know how the hr hand on the chrono of the 7750 is clutched? I'm a little scared to take any more screws out. Quote Link to comment Share on other sites More sharing options...
imajedi Posted May 27, 2012 Author Report Share Posted May 27, 2012 Just in case anyone is following to learn a thing or two, I have some stuff figured out. The tilt pinion goes in with the small gear down and is in continuous contact with the 4th gear which runs the cont. second hand. The pinion is actually tilted during engagement of the chrono to bring the top thicker gear into contact with the center gear of the Chrono and begin the second hand movement. I find it amazing that they actually tilt this thing and it still rotates smoothly in the bearings. The hour hand is run basically completely independant of the rest of the chrono and is on the other side of the watch movement. I.E. I need to take off the hands and face and get to the other side to fix my problem with the hr. hand not working. :-( It turns out the 12 hour accumulater uses a PLASTIC break. Anyone want to take bets that the PLASTIC piece is the one not working. Uhhhhh plastic. Even the idea of having it in there turns my stomach. To get to the other side this project will require some more tools so this will have to go on standby until the tools arrive. I found this article by Walt Odets that describes the 7750 Chrono in detail with pics. Incredible article. http://www.timezone.com/library/horologium/horologium631672313433425752 I'm also using this website http://www.eta.ch/swisslab/7750/7750.html Quote Link to comment Share on other sites More sharing options...
Jkay Posted May 27, 2012 Report Share Posted May 27, 2012 My goodness ... you're a brave man. And apparently have a big brain to match! Go for it. Quote Link to comment Share on other sites More sharing options...
AstroAvia Posted May 29, 2012 Report Share Posted May 29, 2012 (edited) imajedi, congratulations on your attitude! I myself did begin learning how to (dis)assemble movements by doing it with the 7750. It's been dozens now... As for the oscillating pinion: "thick gear" goes down. Be careful, though. The small post has to sit properly down below, otherwise you risk breaking it when replacing the chrono bridge. As for the main spring: hack the movement instead of releasing the main spring power. Pull the stem all its way out. Last, but definitely not least, you MUST take a look at this (if you haven't yet). EDIT: I just realized I am late to this thread, as you have already found out many of the most valuable information by yourself. But I insist the oscillating pinion goes the other way around (Walt Odets got it wrongly described in his picture). I rationalize it as follows: by tilting, the lower gear of the pinnion needs higher/longer/thicker teeth in order to keep engaged with the fourth wheel. I congratulate you again. Edited May 29, 2012 by AstroAvia Quote Link to comment Share on other sites More sharing options...
chronoluvvv Posted May 29, 2012 Report Share Posted May 29, 2012 nice work ! Quote Link to comment Share on other sites More sharing options...
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