andreww Posted February 6, 2009 Report Share Posted February 6, 2009 Just wondering if The Zigmeister or any of our other movement pros could chime in on why this happens... When the chrono is activated on the 28k 7750, the minute totalizer flips over when the chrono second hand is at about 58 seconds. Not a big deal unless you are timing an event that last 6 minutes and 59 seconds, as your reading would actually be 7 minutes 59 seconds. Is this some sort of design flaw, and can it be fixed with service? My 21k 7750s function as they should, so it seems like a flaw with the 28ks only. Link to comment Share on other sites More sharing options...
RWG Technical Posted February 6, 2009 Report Share Posted February 6, 2009 It can't be fixed, it's a design issue. The tolerances are in the fractions of a mm for the tab and gears that make up the minute counter, and there is a precise alignment of all the part if you want it to work. Even with all the parts lined up and adjusted perfectly, the minute counter starts to flip over before 12, nothing can be done to change it... RG Link to comment Share on other sites More sharing options...
andreww Posted February 6, 2009 Author Report Share Posted February 6, 2009 It can't be fixed, it's a design issue. The tolerances are in the fractions of a mm for the tab and gears that make up the minute counter, and there is a precise alignment of all the part if you want it to work. Even with all the parts lined up and adjusted perfectly, the minute counter starts to flip over before 12, nothing can be done to change it... RG Thanks Zig, I assume that the ETA version works as it should? Link to comment Share on other sites More sharing options...
RWG Technical Posted February 6, 2009 Report Share Posted February 6, 2009 Yes, the ETA7750 starts to tick over at 12, not before. If it was adjustable on the Asian 7750 I would modify it, but for some reason they got the alignments of the gears slightly wrong, and because of this and the precise alignment required to get the seconds gear to switch over the minute gear, there is no way to fix it...it's just one of those things we have to live with. RG Link to comment Share on other sites More sharing options...
andreww Posted February 6, 2009 Author Report Share Posted February 6, 2009 Are all a7750 28ks like this? People have often speculated that there is more than one manufacturer of the a7750, if all of them have the same flaw, it seems to me there would only be one manufacturer. Link to comment Share on other sites More sharing options...
slickdick Posted February 6, 2009 Report Share Posted February 6, 2009 I've recently read on rwg a member reporting his new a7750 based watch flipped over on 12. Can't remember his name or topic tho. Link to comment Share on other sites More sharing options...
Djole Posted February 6, 2009 Report Share Posted February 6, 2009 My a7750 flipps over exactly at 12. Link to comment Share on other sites More sharing options...
Toadtorrent Posted February 6, 2009 Report Share Posted February 6, 2009 I've recently read on rwg a member reporting his new a7750 based watch flipped over on 12. Can't remember his name or topic tho. Better send that one back to the dealer. QC checks failed...it was supposed to be incorrect to differentiate it from a gen Swiss movement. Interesting question Andrew...I wondered the same thing for the longest time...never thought to question it. Link to comment Share on other sites More sharing options...
andreww Posted February 6, 2009 Author Report Share Posted February 6, 2009 My a7750 flipps over exactly at 12. Are you sure that its 28k though? If it has a fine regulator on the balance it is more than likely a 21k model. Link to comment Share on other sites More sharing options...
Djole Posted February 6, 2009 Report Share Posted February 6, 2009 It has a fine regulator on the balance, so it's a 21k i guess ? I am not sure... Link to comment Share on other sites More sharing options...
andreww Posted February 6, 2009 Author Report Share Posted February 6, 2009 What model watch is it? Link to comment Share on other sites More sharing options...
Djole Posted February 6, 2009 Report Share Posted February 6, 2009 Tag/Heuer carrera brown. Link to comment Share on other sites More sharing options...
FxrAndy Posted February 6, 2009 Report Share Posted February 6, 2009 My Porto flips just before Link to comment Share on other sites More sharing options...
mjmurphy926 Posted February 6, 2009 Report Share Posted February 6, 2009 I've recently read on rwg a member reporting his new a7750 based watch flipped over on 12. Can't remember his name or topic tho. That may have been me slick. I posted that I received a skyland v3 that flips right at 12:00. The minute totalizer starts to move at about 2-3 seconds before 12 and "snaps" to the next minute right at 12:00. I am sure it is the 28.8k movement. I would like to send it to The Zigmeister for servicing, but I'm afraid that a cleaning will fix this "flaw" and it will advance a couple seconds before 12:00 like all my other a7750s. Link to comment Share on other sites More sharing options...
andreww Posted February 6, 2009 Author Report Share Posted February 6, 2009 Tag/Heuer carrera brown. Interesting. As far as I know the Carreras have all been 28k, but I have never seen one with a fine adjustment regulator. Link to comment Share on other sites More sharing options...
Samurai Posted February 6, 2009 Report Share Posted February 6, 2009 The Grand Carrera is 21.6K with regulator. My C1....which is a 28.8K with regulator (this is the new modified movement being used on some reps)....ticks over exactly @ 12....I think I mentioned this in my initial review of the watch as well. Most or all of my 7750x28.8K....move around 58 sec. Link to comment Share on other sites More sharing options...
andreww Posted February 6, 2009 Author Report Share Posted February 6, 2009 The Grand Carrera is 21.6K with regulator. My C1....which is a 28.8K with regulator (this is the new modified movement being used on some reps)....ticks over exactly @ 12....I think I mentioned this in my initial review of the watch as well. Most or all of my 7750x28.8K....move aroun 58 sec. Thats what I was thinking, that it was a Grand Carrera. Mystery solved. I am aware of the 28k with regulator, but those are new and not in that many watches. Hopefully it will become the standard movement for our reps! Link to comment Share on other sites More sharing options...
Djole Posted February 7, 2009 Report Share Posted February 7, 2009 (edited) Is there any way to tell if it's a 28k8 or 21k6 ? I can make some pictures if needed. Since i am a newbee i have no idea what C1 is... Edited February 7, 2009 by Djole Link to comment Share on other sites More sharing options...
scoobs1971 Posted February 7, 2009 Report Share Posted February 7, 2009 It can't be fixed, it's a design issue. The tolerances are in the fractions of a mm for the tab and gears that make up the minute counter, and there is a precise alignment of all the part if you want it to work. Even with all the parts lined up and adjusted perfectly, the minute counter starts to flip over before 12, nothing can be done to change it... RG Is this the same reason why starting the chrono will first cause the chronosecs to jump back a little before it starts counting? The ETAs seems to start immediatly from 0. Link to comment Share on other sites More sharing options...
RWG Technical Posted February 7, 2009 Report Share Posted February 7, 2009 Is this the same reason why starting the chrono will first cause the chronosecs to jump back a little before it starts counting? The ETAs seems to start immediatly from 0. Not really...from the stopped position, the hammer is holding the seconds gear fixed in place, when you press the button to start the chrono, the hammer releases, and at the same time the tilting pinion engages into the center seconds gear. If your tilting pinion isn't adjusted correctly, there could be a slight movement of the seconds gear before the tilting pinion engages. Remember that the seconds gear is free to spin around, it is only stopped by a brake lever, the reset hammer, or the tilting pinion, anytime you switch modes, one of these has to disengage and the other engage to prevent the hand from moving, any slight misadjustment between any of these 3 items and the hand can swing freely. RG Link to comment Share on other sites More sharing options...
involt Posted February 7, 2009 Report Share Posted February 7, 2009 Is there any way to tell if it's a 28k8 or 21k6 ? I can make some pictures if needed. Since i am a newbee i have no idea what C1 is... The easiest way is starting the cronograph and counting the ticks of the second hand between two minute markers. Three ticks = 21600; four ticks= 28800. Link to comment Share on other sites More sharing options...
SMP Chrono Posted April 15, 2009 Report Share Posted April 15, 2009 Now that's interesting. My SMP Chrono also has this flaw, the chrono minute hand starts to tick over at 58 seconds and jumps to the next minute at 59 seconds. This sort of annoys me. I have learned from this thread that this is indeed a design flaw. Can't the responsive (poorly made) parts/gears simply be exchanged by their respective genuine ETA counterparts? If so, what are they? Link to comment Share on other sites More sharing options...
azerbyjam Posted April 15, 2009 Report Share Posted April 15, 2009 Francisco covered it HERE Link to comment Share on other sites More sharing options...
SMP Chrono Posted April 16, 2009 Report Share Posted April 16, 2009 Francisco covered it HERE Thank you VERY much!! Link to comment Share on other sites More sharing options...
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