Bike Mike Posted January 1, 2010 Report Share Posted January 1, 2010 I already PM'd this to The Zigmeister, but I know he is away for some time so I figure I would post this here. I figure it would give those wanting to attempt a A7750 service, what you might expect to go through on these Chinese movements. I have already worked on a variety of ETA 2824's, 2836's, 6497, etc, so I am not a noob under a loop. But these all being ETA movements I have not yet worked on our Asian counterparts. Enjoy and please thrown in your $0.02 to help me get this sorted out. Currently learning to service one of my A7750, 28.8K movements. The movement was running typical A7750 style prior Quote Link to comment Share on other sites More sharing options...
Drulee Posted January 1, 2010 Report Share Posted January 1, 2010 Are you sure you didn't spill a drop of Tequila into the works at some point Man, thanks a lot, I was just starting to feel confident enough to maybe get into the A7750 a bit further. Now I know I'd better put more time into the 6497s before doing any more than a keyless fix or date wheel change But it definitely sounds like something is receiving or applying a bit too much force when in the dial side up position. I'd first examine any gear/cog that is "top heavy" when in this position - maybe there is just enough weight to misalign the teeth ??? EDIT: obviously I'm a complete amateur (I hate the word Noob) at this Quote Link to comment Share on other sites More sharing options...
jmb Posted January 1, 2010 Report Share Posted January 1, 2010 I have a new DG2813 from ofrei that does the same thing! Will run forever dial-down, but as soon as dial is turned up it will stop within a couple of seconds. Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted January 1, 2010 Author Report Share Posted January 1, 2010 But it definitely sounds like something is receiving or applying a bit too much force when in the dial side up position. I'd first examine any gear/cog that is "top heavy" when in this position - maybe there is just enough weight to misalign the teeth ??? This is what I am down too right now. Jewels between the too plates that at not aligning within spec, that allow for enough play while running dry, but not enough when oiled. Thinking about appling oil to each wheel and stoping at the escape wheel to see what I get as this is where you have the least amount of power and the slightest amount of drag means enough binding to overcome the little power that is there. Quote Link to comment Share on other sites More sharing options...
Toadtorrent Posted January 2, 2010 Report Share Posted January 2, 2010 Whooaah...that really shows me I'm not ready for a 7750 yet...yowzaaa...out of my league. Quote Link to comment Share on other sites More sharing options...
Francisco Posted January 4, 2010 Report Share Posted January 4, 2010 Well, you have done everything you should to find the problem. Something is wrong and it is there.... normally it is a problem with a jewel... broken or, as you say, misaligned. If you still want to find the problem, I suggest you to change one plate each time. If after swapping plates, still not runnign well, change gears.... Regards, Francisco Quote Link to comment Share on other sites More sharing options...
sander Posted January 4, 2010 Report Share Posted January 4, 2010 I once had the same problem. It took me a while to find that one of the jewels on the pallet fork was not glued in properly. An other option is too much oil. I know it's hard to believe but most of the time this is really the case. If I were you, I would start all over again with cleaning all the parts. good for your practice as well Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted January 5, 2010 Author Report Share Posted January 5, 2010 Well, you have done everything you should to find the problem. Something is wrong and it is there.... normally it is a problem with a jewel... broken or, as you say, misaligned. If you still want to find the problem, I suggest you to change one plate each time. If after swapping plates, still not runnign well, change gears.... Regards, Francisco Thanks Francisco. Of course I want to find the problem. I am a OCD Engineer that has to fix everything! As I mentioned I checked all the jewels. They are not broken and not cocked in both the main or train wheel bridge plate (have not built it up beyond this as it is giving me the issue). So I am thinking it has to be the opposing jewels in those 2 plates not lining up perfectly. I thought about swapping plats, however the movement has nice perlage decoration on the bridge and my replacements do not. Not like the movement is visible Quote Link to comment Share on other sites More sharing options...
bjl3910 Posted January 5, 2010 Report Share Posted January 5, 2010 Thanks Francisco. Of course I want to find the problem. I am a OCD Engineer that has to fix everything! As I mentioned I checked all the jewels. They are not broken and not cocked in both the main or train wheel bridge plate (have not built it up beyond this as it is giving me the issue). So I am thinking it has to be the opposing jewels in those 2 plates not lining up perfectly. I thought about swapping plats, however the movement has nice perlage decoration on the bridge and my replacements do not. Not like the movement is visible Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted January 6, 2010 Author Report Share Posted January 6, 2010 Ok this is kind of scaring me now.. Rethinking that 7750 tear down and build up now huh? Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted January 10, 2010 Author Report Share Posted January 10, 2010 Well I found out what the issues was. The impulse stone on the balance was slightly engaged in the pallet fork while dial side down. Dial side up, the stone was just skimming the top of the fork causing the amplitude drop and stoppage. There seems to be a lot of up down play in the balance wheel as well. So, how can this be fixed? My thought was to lower (press towards the dial) the main plate cap & balance jewel housing, this would bring the impulse stone more into the fork. Then lower (press towards the dial) the upper balance cap & balance jewel to reduce the up play in the balance. Still don Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted January 18, 2010 Author Report Share Posted January 18, 2010 ISSUE RESOLVED!!!! FINALLY! Pressed the pallet fork shaft down slightly to raise the pallet fork to the impulse stone, as the impulse stone was as low as it could go. Also found out the lower balance staff had busted and gotten stuck into the jewel cap assembly. This made it look the as if the staff was good and attached to the balance. Replaced the balance after the fork adjustments and the movement fired right up and ran like a thoroughbred in all positions! Thanks for the help guys! Quote Link to comment Share on other sites More sharing options...
Tressles61 Posted March 10, 2010 Report Share Posted March 10, 2010 ISSUE RESOLVED!!!! FINALLY! Pressed the pallet fork shaft down slightly to raise the pallet fork to the impulse stone, as the impulse stone was as low as it could go. Also found out the lower balance staff had busted and gotten stuck into the jewel cap assembly. This made it look the as if the staff was good and attached to the balance. Replaced the balance after the fork adjustments and the movement fired right up and ran like a thoroughbred in all positions! Thanks for the help guys! Well... I guess it's time you start doing repairs for board members. Quote Link to comment Share on other sites More sharing options...
redwatch Posted March 10, 2010 Report Share Posted March 10, 2010 Whooaah...that really shows me I'm not ready for a 7750 yet...yowzaaa...out of my league. +1 - but we'll get there Toad! Awesome post Mike! Thanks for sharing your process and adventures! (Makes me wish we still had the ability to save favorite posts like we used to be able to) Quote Link to comment Share on other sites More sharing options...
Toadtorrent Posted March 12, 2010 Report Share Posted March 12, 2010 +1 - but we'll get there Toad! Awesome post Mike! Thanks for sharing your process and adventures! (Makes me wish we still had the ability to save favorite posts like we used to be able to) I convert them to PDF and save them!!! Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted March 19, 2010 Author Report Share Posted March 19, 2010 Thanks guys! I have done 2 more A7750's since. Must say the Asian movements are a lot more challenging, which makes it fun for me. The ETA's you just put together and they run. Not so with the Asian movements. Well... I guess it's time you start doing repairs for board members. I actually slowly have been doing it. I have a couple members watches with me now. I just don't have the time to do it with a full time job. So I can not do quick turn arounds like Z can. Quote Link to comment Share on other sites More sharing options...
14060 or 16610? Posted March 26, 2010 Report Share Posted March 26, 2010 Thanks for sharing your experience. I only have about a dozen A7750s under my belt, so I'm not exactly an expert. But I have found with symptoms like you described it is usually related to the balance jewels and/or balance pivots, and usually closer inspection of these parts is in order. For instance, I currently have an A7750 that I was servicing and broke a balance spring. I am awaiting new ones from JB (pieces in parts bin and spare movements wouldn't work). The movement is completely assembled and if I wind it up it keeps great time if the missing jewel side is up. The moment that side is put down, the balance slows and the amplitude drops severely (no timing machine but I can see it). It will even stop after a while. Flip that side back up and all is well again. Of course installing the cap jewel when the new spring arrives will make it run fine. Out of curiosity, what "thinner" oil are you using? I use 9010 and D5 for most things, and pretty much try to stick to the ETA oiling chart, but have some very thin off-brand synthetic watch oil that I will use on occasion. Glad you sorted it out. Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted April 6, 2010 Author Report Share Posted April 6, 2010 I went to a light pallet jewel oil. Along the lines of 941 but not by Moebius. Like yourself, 9010 and D5 are the main staple and follow the ETA oil chart, until some thing like this comes up Quote Link to comment Share on other sites More sharing options...
14060 or 16610? Posted April 14, 2010 Report Share Posted April 14, 2010 It's funny, in just the past couple of weeks I have done another half dozen A7750s, so I now have near 20 complete overhaul and service jobs on this movement. With all the other repairs I've done that weren't part of a full overhaul and service, I have amassed quite a bit of experience. By the way, I am now approved over at RWI as a trusted watch repair tech for A7750s and other movements. See my thread documenting one of my A7750 services step-by-step: http://www.replica-watch.info/vb/showthread.php/what-does-a7750-look-like-52351.html Quote Link to comment Share on other sites More sharing options...
Rolexman Posted February 27, 2011 Report Share Posted February 27, 2011 ISSUE RESOLVED!!!! FINALLY! Pressed the pallet fork shaft down slightly to raise the pallet fork to the impulse stone, as the impulse stone was as low as it could go. Hi Mike, I'm kinda having the same problem. I Received a 7750 which wouldn't run. Traced the problem back to the pallet fork (PF). Switched it out and in runs like a champ. But....I'm trying to understand the problem with the original PF. The original PF had a loose pallet stone so I glued it back in. After that it just wouldn't give enough 'momentum' to the impuls jewel making the balance swing like say only 10 degrees. I inspected the PF with a microscope and compared it to a new 7750 PF and I could not see any differences. Can you explain the thing you did above? Perhaps it's the same problem with mine broken PF. Thanks! Mark Quote Link to comment Share on other sites More sharing options...
Bike Mike Posted April 21, 2011 Author Report Share Posted April 21, 2011 Mark, Man...I am so sorry I did not see this before...I do not get down to this area much. Pallet forks are a very finicky part to deal with. If the stone is off just the slightest amount, the movement will fail to run or run properly. It is all about geometry of the PF stone interface to the escarpment. The lock, input pulse, unlock...cycle repeat... needs to be just about perfect on both sides of the fork. If they impulse face is not at the correct angle or does not make square contact to the escape wheel...you get issues. I have spent a good day making PF work on reps. I strictly put in the time to learn...Now if I can not fix the issue in 5-10 minutes I replace the fork. The issue I had above, was the fork was sitting too high, (away from the dial), that when the movement was turned to dial side up, the free play in the fork was just enough that it did not allow from proper engagement into the escape wheel. I ended up having to move the fork further down (towards the dial) on the arbor. This can be easily done with a staking set. Once I did that, all was good. I hope in the last 2 months you have gotten this sorted. PM me next time you want me to follow up on a post all the way down here. Quote Link to comment Share on other sites More sharing options...
Rolexman Posted April 21, 2011 Report Share Posted April 21, 2011 Mark, Man...I am so sorry I did not see this before...I do not get down to this area much. Pallet forks are a very finicky part to deal with. If the stone is off just the slightest amount, the movement will fail to run or run properly. It is all about geometry of the PF stone interface to the escarpment. The lock, input pulse, unlock...cycle repeat... needs to be just about perfect on both sides of the fork. If they impulse face is not at the correct angle or does not make square contact to the escape wheel...you get issues. I have spent a good day making PF work on reps. I strictly put in the time to learn...Now if I can not fix the issue in 5-10 minutes I replace the fork. The issue I had above, was the fork was sitting too high, (away from the dial), that when the movement was turned to dial side up, the free play in the fork was just enough that it did not allow from proper engagement into the escape wheel. I ended up having to move the fork further down (towards the dial) on the arbor. This can be easily done with a staking set. Once I did that, all was good. I hope in the last 2 months you have gotten this sorted. PM me next time you want me to follow up on a post all the way down here. No problem Mike. I made the post and I replaced the PF like 10 minutes after that I just did not want to tinker with it any longer. So I too forgot about this post, otherwise I would have PMed ya Thanks for your elaborate answer though! Quote Link to comment Share on other sites More sharing options...
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