RWG Technical

Wonderful information, a must read for anyone who is getting work done on a watch, or who has a technical problem. Thanks for posting this. RG

Beautiful job Omega. I have drilled my share as well, and know how difficult it can be, especially when the drill bit breaks off and the broken piece damages the lug... RG

I have not tried an ETA gear to see if it will fit, so far most of the ETA parts I have bought for repairs of the A7750's have not been compatible with the Asian model. May as well try one of these gears with my next supplier order, otherwise there are going to be a lot of handwinds from now on RG

I have done a number of these, but I don't have any pics to share...they are all in the hands of the owners now. RG

I have replaced a number of 2836-2's GMT movements with 2893-2's. In fact I am in the middle of doing one right now, a PAM 029 (or 027, I can't keep the numbers straight). On this particular PAM the movement spacer ring is too small and I need to grind it down to get the 2893-2 to fit into it. The other ones I have upgraded worked ok, other than needing a new GMT hand to fit the 2893-2, I can't remember any real big fitment issues or problems, it all seemed to go together fine. But, as with anything on these reps, what worked on a watch today, may not work tomorrow simply due to the variations in production. I did have a GMTII in for lume once, it came equipped from the factory with a 2893-2 inside, only one I have ever seen, and no idea where it came from... RG

Yes I believe I have seen all versions of the ETA 2836 modified GMT movements produced. Other than the genuine ETA 2893-2 GMT movement, I stopped servicing or even luming the modified GMT movements. Simply because they are too problematic. Gears breaking in two pieces when you remove the hands, hands slipping, poor quality parts, poor design, etc... The failure rate is very high on this model. The 2893-2 models have had zero returns or failures. If you get one and it works, don't frig with it, leave it alone and enjoy it... RG

I am not sure what a CHS model is... RG

Forget the stamps and markings. Check out the balance cap jewel and Kif Trior spring and holder. It's not a Kif setting but something totally different. The Kif setting has 3 cutouts for the spring to fit into, this one has one cutout, it's not the real deal (at least not to my knowledge). I have had a few of these in for servicing, they are not the best and I have had problems getting them to run well after servicing. Never ever had any problems with an ETA following servicing. Trying to get the beat and rate adjusted was a frustrating experience when it should be simple. Maybe I just had a few lemons of these new copy models, or maybe they are simply lemons... My experience has not been good. RG

As we all know, individual parts availibility for the Asian movements, especially the 7750 is non-existant. If you want spare parts, you do as I have done, you buy complete A7750's and tear them down for parts. At $125 per movement, this is not a cheap option and I can't afford to do it anymore. As with any mechanical item, there are typically a few parts that cause all your problems. These problematic parts on the A7750 have been discussed at lenght already and don't need repeating in this post. I want to draw your attention once again to one part that has been taking a beating lately, and it's only on the new version of the A7750. The part I am referring to is the transfer gear between the mainspring winding gear and the autowinder gears. This gear, like all movement gears, has a steel pivot and brass wheel. The steel pivot engages into the mainspring gear, and the brass section engages into the autowinder gears. This gear is the one that will be damaged and stripped of it's teeth when handwinding the watch. What I mean is that this is always the gear that gets damaged if you handwind, and I don't have any more spare gears to replace them. As we all know the servicing and oiling of a factory delivered A7750 is terrible. There are two critical problems which are causing the handwinding gear damage: 1. The click or clutch gear that is directly connected to the rotor is sticky on an unserviced movement. This adds friction when you handwind the watch. The gear is a one way clutch and is supposed to slip and not turn the rotor when handwinding. If you feel the rotor spinning when you handwind, you have a sticky gear. 2. The small transfer gear between the click wheel and the mainspring transfer gear, is always gummed up and doesn't spin freely either. On an unserviced movement the friction from these two gears is enough to cause the mainspring transfer gear to loose it's teeth when handwinding the watch. This damage can only come from handwinding, the gear will not be damaged by the rotor winding the watch. I don't think this damage is being done on purpose by the owners, but keep in mind that the gear material is no match for your finger strength when you handwind. It only takes a slight turn to bend a tooth on the gear, once this happens, and before you know it, more teeth are damaged and the autowinder is not working anymore. Last night I used up my one and only last mainspring transfer gear for a repair. The damaged gear had only two missing teeth (the owner will be sent back the old gear so he can see for himself the damage) and in this case, the owner never handwound the watch. I suspect that it was handwound and damaged before he took delivery. How can you prevent this? Easy, swirl your A7750 in your hand to get it going and set the time and wear it. I'm not selling or suggesting servicing as a solution, I am suggesting you avoid handwinding at all times, especailly on an unserviced watch. Once serviced the problems are corrected and slow and careful handwinding to get the watch started is ok. I handwind all my A7750's, all have been serviced, some going back 3+ years, and have not damaged a gear yet. Of course all is not lost, if you end up with this problem you can always make your watch a handwind model... RG

It could be a number of problems. My first guess would be a broken pivot on the balance staff. Remove the balance kock jewel, and with a 10X loupe, check if the pivot is visible. If it's not the pivot, then my guess would be something touching the balance, maybe the pallet or the hacking lever... It's going to take some troubleshooting to find the problem, but it's a great learning excercise. RG

The first GMT 7750's I saw over a year ago, were not that good. The ones I have been seeing after this are ok. The GMT hand adjustment is in 1 hour steps, but it trackes smooth with the main hour hand when it runs. RG

It does come with the jewels installed. I have not had any luck with SW200 parts and ETA parts, they are totally different. So glad to hear your enjoying the TZ course, with Offshore offering the CD with everything on it, there is no reason to not take the course. RG

The A7750 discussion has to be the longest running discussion on these forums...it never seems to end, no matter how many times it's been said. RG

Makes you wonder how these search engines work, if your not logged onto or a member of this board, how can google pick up the name on the forum... In any case, I think just about any name here would show up in google. @ubi They are all signed after service, only way I can validate if I worked on the watch before... RG

Excellent work, congradulations on a job well done. RG

"Bob's your uncle" is a saying around where I live, it means everything is ok. Bob "nanuq" is a mod here. I didn't want you to mix both up. Sorry for the confusion. RG

No, genuine ETA datewheels work fine... RG

It's certainly worth a try, I hate sending anything back. There is a shortcut you can use also, remove the hands and dial, remove the hour wheel, then with a set of side cutters, carefully squeeze the cannon pin below the top bearing (if you examine the cannon pin with a loupe, you will see the part that the minute hand attaches to, below it a larger bearing surface, and then a narrow part, and then on the bottom a larger bearing again, you want to squeeze below the top bearing surface on the narrow part). There should be a small dent visible somewhere on this narrow part, this is supposed to provide the necessairy friction. What you do is squeeze gently, then turn the crown and test the amount of friction, keep doing this until the friction is normal, about the same as when winding, re-assemble, and Bob (not nanuq) is you uncle... Good luck. RG

The cannon pinion is defective. My guess is that when you move the hands with the crown, there is little to no resistance felt and the hands move very easily. You should feel quite a bit of resistance when setting the time, as much as when you wind the watch. Not a self fix problem, it needs to come apart and be staked to correct it. RG

I don't "not" do things at a whim. Especially if I am charging for my time for a particular service. If you note things or services I don't offer, there is always a good reason behind why I made that decision. Same as not accepting certain watches from certain dealers, or if they have been in the hands of other certain other modders. Experience has taught me hard lessons in both those cases. RG

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The only "new" ETA's I am aware of, are those in the sealed blister packs. Anything else is anyone's guess as to it's condition, "new" with many ETA's means "surplus" and condition unknown. Based on his watchmaker's comments, I would say that this movement was a used surplus one. A genuine "new" ETA, any model caliber, is pristine and in perfect condition and needs nothing for 5 or so years. RG

Try this test, it will indicate were your problem is, if indeed you have a problem. Hand wind the watch about 25-30 turns, slowly and carefully, if you run into any resistance or the rotor spins, stop before you damage the movement. Put the watch aside, and see how long it runs. If you get 36 or so hours, the movement is fine, your autowinder or automatic winder is at fault, this is a uni directional winding movement, and only winds one way, the automatic winder may be part of the problem. RG

If by quality you are referring to the functionality of the movement, vs it's appearance, then the Asian and ETA 7750 are almost on par. And the latest versions of the Asian 7750 have certainly improved on the appearance problems of earlier versions. I have had a number of Swiss ETA 7750's in for swaps, and many of these were old tired out movements in dire need of servicing. Most of these replacement movements showed signs of their age, the click wheel was all gummed up (when handwinding the rotor would spin around), and the pallets were gummed up and the escape wheel also covered in black gunk. A full servicing should have been done, but when the cost of the movement, the cost of the swap, and the cost of the servicing was all combined, it became very expensive, and most elected to not have it done and have me do the basics to get it running. The fact these movements were "Swiss" meant nothing as far as their condition, the condition of the movements was awful compared to the Asian 7750. So which is better, a clean fresh Asian 7750 which may not need servicing immediatly, or a Swiss 7750 that is old and tired, has only 17 vs 25 jewels, and needs to be fully serviced before it can be placed in use... I think this is the point of view of your watchmaker, I have seen the exact same situation a number of times. The quality of the Asian 7750, where it counts (polishing of pivots, fitment of parts, etc) is acceptable, with regular servicing there is no reason they won't last a lifetime. And with regular servicing, parts won't need to be replaced since they won't wear out... RG