New A7753 Service & Analysis

[14060 or 16610?]

For those of you interested: http://www.replica-watch.info/vb/showthread.php/a7753-service-analysis-thread-youve-60596.html

[crystalcranium]

Wow...did I miss this? The rep guys have an A7753 clone now? Looks like the QC is awful but i can wait a little while for them to sort this out.

[Drulee]

Wow...did I miss this? The rep guys have an A7753 clone now? Looks like the QC is awful but i can wait a little while for them to sort this out.

Yup the new PAM Daylights use it.

[14060 or 16610?]

Wow...did I miss this? The rep guys have an A7753 clone now? Looks like the QC is awful but i can wait a little while for them to sort this out.

If history with the A7750 is any indicator, there isn't going to be any improvement in QC.

[hackR]

well done and thanks...

any chance of you cutting/pasting your RWI pix/review here to save everyone a hop?...

[maxman]

Thank you very much 14060,It's infomation like this that makes me love this hobby so much. Members like youself that give of there time and experence to the rep community. I feel that this movement will find It's way Into some reps that we have been waiting years for. Again thank you very much for the break down,absolutely fantastic

[scoobs1971]

Thnx for posting! Curious to the Zigmeister's verdict...

[FxrAndy]

Hmm interesting

[14060 or 16610?]

**REPOST FROM RWI AS REQUESTED**

My day job is pretty busy today, but I was able to spend my lunch hour tearing down the new A7753 movement. This recently released, much-hyped movement allows for the following:

* 3 - 6 - 9 subdial layout with running seconds at 9.

* no sunken datewheel.

* date adjusted by pushbutton located at 10:00.

My first impressions are that the A7753 is well-made. It can be reliable and keep good time for years and years with proper maintenance, not unlike the newest A7750s with which it shares the majority of its parts. Here are some fairly significant differences from its A7750 cousin:

* calendaring retaining plate, jumper, and spring.

* manual-set calendar driving pawl and gear.

* 3:00 subdial gearing.

* 2-position keyless works.

The movement I received was keeping good time. It was sent in for a full service and to repair a jammed datewheel which would not advance either in time-setting mode or via the pushbutton at 10:00. I noticed the mainspring did not "crunch" when reaching a full wind; evidently it was slipping on the barrel walls. This would obviously reduce the power reserve.

I also noticed that the movement was very dirty, with large chunks of dirt and various fibers (white and blue, mostly) found throughout. I even found a dried-up piece of lettuce or some other leaf. The keyless works were bone dry, though the stem and sliding/winding pinions were greased. None of the pivots had any oil on them (I checked thoroughly). The balance jewels *may* have been oiled, as they remained stuck to each other during removal. If you know A7750s, you know this is all very routine stuff.

I took many pics and will post back with more detail when I'm able. But I wanted the folks here to know a thorough teardown and analysis complete with pics is on its way.

Until next time...

G

**REPOST CONTINUED**

If you've seen similar pics and know all about the non-A7753-specific parts, sorry. I'm posting them up anyway for folks who don't know what's involved in servicing these movements.

For starters, I removed the caseback. This caseback was already loose, so no need to use a wrench or 12-point die.

The first thing I noticed was that the date lever was stuck. I pushed it back out towards the case to free it up, and the date wheel was able to "settle" on a single date (it was previously jammed in between two dates). With this lever unjammed, I was able to observe the date changing by advancing the time. However, the quick-set date function via the button at 10:00 would not work. Each time the button was depressed, the date did not advance, and the lever would not return to resting position. This clearly pointed to lack of lubrication and a possible misalignment of parts.

Next I removed the hands, dial, and calendar retaining plate.

Here you get a better look at the components on the dial side. Note that the date wheel and the parts sitting inside of it are unique to the A7753 and, as far as I know, not interchangeable with the A7750 (the exception *might* be the date jumper). Notice the anti-jam date advancing gear.

Some more parts unique to the A7753. The intermediate gear is used to transfer motion from the 30-minute counter gear to the corresponding post in the tricompax configuration. Very similar in concept to the modifier plate in the tricompax-modified A7750s. Unfortunately, the extra play is still there, at least on this particular movement. The fit and finish of the gears is just not up to the standards of the gen ETA 7753. On a positive note, we get the lower positioning and resulting height, which eliminates the sunken datewheel. The date gear is used to advance the date wheel. It is actuated by a lever underneath the calendaring plate, which you will see next.

I removed the calendaring plate. Everything on the right side of the movement looks pretty familiar, nothing new here. But on the left notice the lever and spring. When actuated, the lever (more of a prawl EDIT: I mean "pawl") turns the date gear via the teeth on the underside (date gear flipped to show these teeth). Remember how the date was jammed when I received this watch? The lever was very stiff on its post and was difficult to actuate. I'm betting it's because the pivot and the spring (where it contacts the lever) were bone dry and causing too much friction. The date gear itself was also dry on its post, causing even more friction. Not hard to see why there were problems.

Notice this special spring which engages with the date gear. It is aligned by 2 posts and affixed with a screw screwed into a specially-drilled hole. This makes the calendaring plate also unique to the A7753. It

[hackR]

really nice work...thanks!...

[ar0401]

Very instructive, G. Thanks a lot!

[Toadtorrent]

For those of you interested: http://www.replica-watch.info/vb/showthread.php/a7753-service-analysis-thread-youve-60596.html

Awesome...bring it over here...we love stuff like that!!!!

[dluddy]

Thanks for sharing this here. Excellent review

[krpster]

That was great! Thanks.

[RWG Technical]

Great review.

Looks as if the sweater factory is next door to the salad factory.

Interesting to note similar yet different problems when compared to the one I tore down. But in each case, nothing that a servicing can't fix or cure.

Thanks for posting, good to get different viewpoints and opinions, the membership of RWG are the ones who gain from this great insight.

[14060 or 16610?]

The rest of the teardown is pretty routine for an A775x movement. Lots of dirt and grit. This one in particular was littered with metal shavings all over the mainplate and inside the mainspring barrel. Absolutely terrible. I still don't see how folks leave these running unserviced from new. Even if it's running, it's just not right in my opinion. But of course that's a debate for another time. Your mileage may vary.

The reassembly is complete, and the movement is keeping very good time. However, I believe I have found a weak spot. It's no surprise. I'm still trying a few workarounds, but they don't look promising. I'll have more info, and a video, shortly...

[chronoluvvv]

awesome stuff

Thanks !

[14060 or 16610?]

Reassembly was also pretty routine and on par with that of the A7750. After all, most parts are shared.

Look at these excellent analyzer results:

Now for the weak spot of the movement. Click on the video to see. Can anyone guess what the resulting problem is?

I have to sign off for now but will be back again...

[Jkay]

I had never heard of you before this, but you seem to be an A #1 service guy! Thanks for being a part of our community.

[Toadtorrent]

Looks as if the sweater factory is next door to the salad factory.

Great!!

Thanks so much for posting this and being such a technically aware member of the community!!

[babola]

Now for the weak spot of the movement. Click on the video to see...

Oh crapola...

I wish I haven't see that video G.

So it appears the quickset date wheel is "securely" held in it's place by the bottom of the dial only, pin at the bottom of the wheel supported and rotating on a single jewel only?

Wonder if that wobbliness is only a single case or a design fault symptomatic to all new A7753 mov'ts

Thanks for the mov't tear-down and a review, once again!

[14060 or 16610?]

Oh crapola...

I wish I haven't see that video G.

So it appears the quickset date wheel is "securely" held in it's place by the bottom of the dial only, pin at the bottom of the wheel supported and rotating on a single jewel only?

Wonder if that wobbliness is only a single case or a design fault symptomatic to all new A7753 mov'ts

Thanks for the mov't tear-down and a review, once again!

Actually there is no jewel, but that's not a bad thing. It's not needed here. The date advancing gear sits on a post that protrudes from the calendaring plate. The problem here is that the parts do not mate properly. The wheel can move around laterally and wobble far more than it should. As a result, it binds and jams, and won't advance the date as it should.

I am guessing that the poor tolerances affect just this particular movement. But I honestly have not seen enough of them to know for sure. I do know the watch was new and the quickset function was already jammed when it was sent to me. It turned out to be a two-fold problem. In addition to the sloppy gear fitment, the advancing lever kept getting stuck. It was completely dry on its post, and the post required some smoothing. The lever action was easily resolved, and it now actuates and returns as it should.

Any way you look at it, not a good sign. I tried removing the jumper altogether and reinstalling the retaining plate. With the jumper removed, the date wheel would advance, but it still required far more effort than it should have. This confirms my suspicion that the advancing gear is at fault.

This was my email to the owner last night:

Hi XXXXX,

I wanted to follow up as I said I would. I have worked several more hours on your movement. In all, I have done the following:

* weakened jumper spring to reduce jumper friction

* lubricated face of jumper

* lubricated each individual datewheel tooth

* lubricated surface that datewheel rides on

* lubricated top and bottom of quick set gear

* lubricated post for quick set gear

* lubricated underside of calendaring retaining plate

* lubricated quick set gear jumper spring

* lubricated teeth of quick set gear which engage jumper spring

I have lubricated every part that could contribute to drag on the datewheel, but so far it hasn't helped. I have only gotten the quick set date function to work a few times. Most other times it just jams.

I included photos and a video in this link: http://www.replica-watch.info/vb/showthread.php/a7753-service-analysis-thread-youve-60596p3.html To save time I won't email them to you; please just visit the link. The video is posted last. Please click on it and view it. You will see the incredible amount of play and wobble in the quick set gear. It can move up and down and side to side, so it becomes crooked and jams when actuated by the lever. The post is too short and too small in diameter, and the gear itself is too tall, so it rubs the calendaring plate below as well as the retaining plate above.

The quick set lever itself I was able to fix with some smoothing of the pivots, a good cleaning, and proper lubrication. It moves freely now, and returns as it should, without excessive friction. The problem is truly the quick set gear. Modifying the calendaring plate and post simply are not good options. There are too many problems associated with modifying them.

The last step is to try and modify the gear itself, possibly shave a tiny bit off the top and bottom to reduce rubbing on the plates above and below. I really don't know if this will help, but it is worth a shot. It is very late now, and I have easily spent 2x the number of hours I normally spend on other movements. Tomorrow I will try to shave the gear very gently and gradually if that's OK with you. If it doesn't succeed, unfortunately you will have to live without this function. The date will still advance with the time, you just won't have quick set date function. I don't know if you know this, but the gen ETA 7753 is also very prone to jamming. Many gen 7753 owners do not have working quick set date because it jams easily. It is a poor design to begin with, even in gen form, and poor fit and finish of rep A7753 parts doesn't help.

Like I said, I will try this last step tomorrow and let you know the outcome. I'm done for tonight.

Thanks.

G

Edited October 7, 2010 by 14060 or 16610?

[babola]

Actually there is no jewel, but that's not a bad thing. It's not needed here. The date advancing gear sits on a post that protrudes from the calendaring plate. The problem here is that the parts do not mate properly. The wheel can move around laterally and wobble far more than it should. As a result, it binds and jams, and won't advance the date as it should.

I am guessing that the poor tolerances affect just this particular movement. But I honestly have not seen enough of them to know for sure. I do know the watch was new and the quickset function was already jammed when it was sent to me. It turned out to be a two-fold problem. In addition to the sloppy gear fitment, the advancing lever kept getting stuck. It was completely dry on its post, and the post required some smoothing. The lever action was easily resolved, and it now actuates and returns as it should.

Any way you look at it, not a good sign. I tried removing the jumper altogether and reinstalling the retaining plate. With the jumper removed, the date wheel would advance, but it still required far more effort than it should have. This confirms my suspicion that the advancing gear is at fault.

Many thanks for this explanation G, let's hope it was just a single case this time, but as you pointed out it is a design fault nevertheless and an 'accident' just waiting to happen.

[redwatch]

God I love this place!! Between you and the Zigmeister, you are both providing some excellent insights here! Thanks so much for taking the time to do this. It take you guys long enough just to do the service, but to document each step as you do it is just super!

[14060 or 16610?]

Thanks for the props everyone. I can really get into this stuff when time permits.

Here are some measurements, for those of you wondering about A7750 swapability (did I just invent a word?):

30.39 diameter

07.42 thickness (excludes rotor and post protrusion)

00.19 all 3 subdial posts

02.00 hour cannon

01.20 minute cannon

00.20 center chrono post

Hope this info is useful. As The Zigmeister pointed out in his excellent review, the datewheel alignment with the dial is going to be an issue if you plan on swapping one of these in place of an existing A7750.