Movement review, Asian 7750 with running seconds at "3"

[onzenuub 308]

This was originally posted by Ziggyzumba @ RWGcc, with his permission it has been reposted over here.

 

Movement review, Asian 7750 with running seconds at "3"

 

This is the latest in a long line of modified Asian 7750's. The Asian's have come out with more variants than the Swiss ever did, or thought of...there seems to be no end to the uses of this movement.

 

I think the Asian 7750 has been given and continued to be bashed as a "crappy" movement, based on teething problems with the original version that was produced. The 28.8K models, are in my opinion as good mechanically as the Swiss models. Astetically the Asian model is 8 out of 10 compared to the Swiss. I have not had a return of a Asian 7750 that I have serviced in the past 12 months. Just like the Canada Customs BS myth that won't go away, the Asian 7750 needs to be seen for what it is, a good movement, well executed, but poorly serviced as delivered.

 

Going back 2+ years when we first had a look at the Daytona with running seconds moved to the 6 position (remember the first renditions were based on Swiss ETA 7750's, not Asian models). These first Daytona's were over $1K if I remember well, but suffered with the same problems as all versions did - poorly designed modification with too much friction in the running seconds drive gears (all 5 of them).

 

A correctly designed transfer gear system would actually work, if only someone did it...and maybe they finally did...

 

So now we have the newest rendition of the 7750, and this time we have taken the running seconds from it's normal "9" position, and moved it all the way across the dial face to the "3 position. Added to this, they moved the 30-minute timer from the "12" to the "9" position, but since we have had quazi 7753's for some time now (which moved the 30-minute timer to "3"), moving it to "9" is not a big engineering challenge.

 

So how well did they do?

 

It's probably very unrealistic of me to think my comments and analysis of movements, somehow makes it back to the actual movement designers in Asia. Since I have been offering my suggestions on how to make these modifications work, for over 2 years now, maybe...just maybe...they heard me (finally, now if your hearing this, do the same to the running seconds at 6 A7750's and watch the sales go through the roof...).

 

I won't bore you with the usual teardown of a 7750 photo's we have all seen those...

 

So lets start off with the movement all cleaned up, and the basic movement assembled, and now we will start assembling the chrono parts.

 

Overall view dial side, no bridge installed. Looks like any 7750 at this stage (well, not exactly, the eagle eyed members will spot some mainplate mods)

 

This is the top plate, view from above, date wheels removed for clarity.

 

 

Same plate, bottom view.

 

 

Before I install this plate, I have to put some parts in place for the chrono to work, here they are.

 

 

Note that there are no gears installed for the transfer of the running seconds. If you remember on the running seconds at 6 models, we had to install a new gear, right where the 30-minute output gear is on this model...so where to we pick up running seconds if not where it is located...you'll see...

 

Close up of the 30-minute output at "9" gear and coorresponding jewel.

 

 

First view of how they picked up the running seconds, this is one of the mainplate mods, this hole does not exist on normal 7750's...

 

 

Top plate installed, a challenge at the best of times, even more so, since I had not one (12-hour gear and post) to deal with, but the addition of the 30-minute gear and post to line up and get through the plate. Do you see how the gears that we were just looking at are meshed into each other (small inspection holes show if your assembling the watch correctly).

 

 

Another view.

 

 

These are the posts for the 30 minute hand and the 12-hour one.

 

 

The first part of the running seconds transfer gears, do you see what I do?? Actual gears with pivots, and jewels, wow, what is going on here...

 

 

This part gets installed in the mainplate and will mesh this gear to the movement seconds wheel.

 

 

Here is the parts installed.

 

 

The first of two cover plates for the running seconds transfer gears, note more jewels...

 

 

Overall view with the first cover plate installed, only 3 more gears to go...

 

 

Here is what we have so far, note that it's all jeweled so far, a good sign. Jewels means no friction, no friction, means...well you know the answer...

 

 

Second cover plate, for the remaining 3 gears, more jewels.

 

 

Close up view of the center transfer gear, brass on nickel plated brass, best you can do to have the least friction.

 

 

Small ring pressed in place to hold the gear.

 

 

Location of the last two transfer gears, what is this? more jewels...can't be...

 

 

And actual gears with pivots that ride in the jewels with no friction...unbelievable...

 

 

Overall view with the remaining plate installed, showing the power flow across the movement face.

 

 

Close up of the last gears, and the meshing between them...

 

So there you have it.

 

As in the running seconds at 6 model, we have 5 extra gears taking our running seconds from the "9 O'clock" position on the movement, running it across the dial face, and placing it at the "3 O'clock" position.

 

As we all know, this mod doesn't work on the running seconds at "6" models.

 

But, on this model, they have used correct watchmaking designs and placed 4 of the gears in jewels, with correct pivots, for little to no friction at all. The only gear that is not jewelled is the one that has to fit over the center post, and it can't be jewelled due to it having a big hole in the center.

 

Based on my examination, testing, monitoring of the movement on my timing machine, I think this is a well done modification, and poses no issues to the long term life, or running of the movement. In other words, they finally go the design right. Finally...

 

The movement was no different than any other A7750 that I see, in other words, no oil, or over oiled in some area's, no crap or dirt, just not serviced correctly.

 

Movement has been running flawlessly for the past 2 days, and will be out the door by week's end.

 

Thanks for reading, lets put the pressure on to get this design into a running seconds at 6 model.

[Massimo 53]

Very interesting article, thanks for posting it over here.

[AustinTech 0]

Excellent stuff. That kinda expertise is way beyond my knowledge.

[Luthier 1]

Great post, thanks!!!

I'm wondering... if chinese can do even THAT... why the hell they stole spaceship drawings from Russia???

[greg_r 81]

Fantastic - thanks for the re-post Onze!