Wandering Asian 7750 Hour Totalizer Hand - New

[freddy333]

THE LEGEND

3. If the hand moves when the movement is out of the case, you have to take the dial and hands off, and the top bridge off to try and find out why. It could be a defective chrono reset arm, or the plastic brake lever, or too much friction on the 12 hour wheel clutch etc...

THE PROBLEM

I am trying to repair yet another secs at 6 Asian 7750 that has the same problem my secs at 9 7750 had -- the hour totalizer (subdial at 9) continues to move when the chronograph is off. In this case, the problem continues when the movement is out of the case, so I know I am dealing with one of the components Ziggy mentioned above.

THE STORY SO FAR

I removed the top plate of the movement (note the 3 jewels in the plate where the pins of the 3 subdial gears fit through)

I stopped here to take a picture of the bridge and extra gearing the factory added to relocate the running seconds hand from the stock 7750's usual location (9 o'clock subdial) to the proper location of the running seconds on a modern 1165xx Daytona (6 o'clock subdial)

THE PLOT THICKENS

I then lifted-off all of the gears except for the top one (the top gear seems to be press-fit onto its pinion)

I stopped there and wanted to ask Ziggy or anyone who has worked on these movements a few questions before I proceed.

THE 3 QUESTIONS

1 - How do I remove this 1 remaining gear (it does not simply lift-off like the other 7 gears did)?

2- Are there any gotchas that relate to either removing or reinstalling the bridge & remaining gear (are there any special tools required for setting clearances, etc.)? That is, once I figure out how to remove the remaining gear, can I just remove the 3 screws & lift off the bridge -- is reassembly just a reversal of the removal procedure?

3- Am I correct that none of the gears or jewels either on this bridge or in the top plate gets oiled during reassembly?

______________

FOOD FOR THOUGHT

As an aside (regarding the oil, or lack of it in these secs at 6 7750s) - I have found that every one of these secs at 6 7750s have very 'twitchy' seconds hands. That is, instead of a 'sweeping' motion as the hand moves around the seconds subdial, the movement is quite erratic & stuttery. As this erratic behavior does not seem to effect any of the secs at 9 7750s, I think it is safe to say that the problem is related to the additional gearing used to relocate the running seconds hand.

Looking at the design of the additional bridge and gearing, this could be due either to the 'play' between the final 2 gears or it could be due to the lack of precise fit of the gears onto their pinions (there is clearly a bit of slop in there) or it could be due to the lack of lubrication (or any mixture of the above).

I know that using oil to lubricate the additional gearing for these relocated running seconds hands adds additional drag and friction to the already overloaded movement. But I am wondering if Ziggy or anyone else has ever considered (or tried) using powdered graphite to lubricate the extra gearing since, being a dry (very fine powder) lubricant, it should not add much (if any) additional drag & might be just the thing to resurrect some of the prematurely dead Daytonas.....at least as a stop-gap measure until the factories build a better mouse trap. Anyone try this stuff yet (I am hesitant to test the theory on my watch since it is one of the few that are still running.....if it ain't broke, don't fix it)?

[RWG Technical]

I did a quick read, as I am pressed for time...

You can remove the top plate as an assembly, without taking the first cover gear you removed. In other words, you can reinstall that cover and all the gears, and remove the other three screws, recessed ones.

The one remaining gear does not have to come off to get the assembly off, the top plate has a hole cut out in it, and this gear remains attached to the mainplate. Removal of this gear, is like any other chrono gear, you need a puller for it.

The biggest "got ya" is trying to get the reset spring to stay in place on the hammer and the lever. If you have the ETA drawings it does help a lot, but even with them, it's a royal pain to get this spring in place, and even more difficult to install the top assembly without having it pop out of place.

Apart from the chrono tilting pinion and autowinder reversing gears and plates on the backside of the movement, installing this assembly is very tedious, and really impossible to type a explanation on, sitting at a bench watching someone do it, straight forward, doing so remotely is hard.

RG

[RWG Technical]

Oh, and on the lubrication of these gears...

Keep in mind, lubrication is there to prevent wear, the further away you get from the mainspring, the less tension and thinner oils you use, the escape wheel uses a miniscule amount of oil.

If you even slightly oil these gears, the movement will come to a grinding halt...nothing other than watch oils should ever be considered, graphite I have only seen on the El Primero sealed mainspring barrel.

RG

[freddy333]

The one remaining gear does not have to come off to get the assembly off, the top plate has a hole cut out in it, and this gear remains attached to the mainplate. Removal of this gear, is like any other chrono gear, you need a puller for it.

The biggest "got ya" is trying to get the reset spring to stay in place on the hammer and the lever. If you have the ETA drawings it does help a lot, but even with them, it's a royal pain to get this spring in place, and even more difficult to install the top assembly without having it pop out of place.

Apart from the chrono tilting pinion and autowinder reversing gears and plates on the backside of the movement, installing this assembly is very tedious, and really impossible to type a explanation on, sitting at a bench watching someone do it, straight forward, doing so remotely is hard.

Thank you. This info helped.

When I removed the bridge, I found the hour hammer spring had slipped off the hour hammer operating lever, which released the hour hammer and allowed the white plastic hour counter lock (the component that 'brakes' & stabilizes the hour totalizer hand) to swing away from the hour totalizer gear (I have removed the hour totalizer gear in this picture)

I am assuming the spring had somehow become dislodged while the movement was out of the case (I had removed the movement while I was installing a crown/tube). However, it could have been dislodged during removal of the bridge, but I am hoping it was the former & not the latter case.

The only other thing that looked different than the layout in the ETA diagram of the braking assembly

was the way the k-n-o-b end of the plastic hour counter lock (the white 'L' shaped piece in the 1st picture) did not quite fit all the way into the cut-out of the hour hammer operating lever as it does in the diagram above (the round bit just sat in the cut-out and pivoted as the parts moved). But everything seemed to function properly when I moved them manually, so I just re-engaged the spring around both the hour hammer operating lever & the hour hammer (it actually was not difficult once I figured out how to hold the metal bits with my finger while expanding & slipping the leg of the spring around the lever).

And then I reassembled everything up to the dial (I only attached the hand for the hour totalizer so I could test it thoroughly before completing the reassembly).

[freddy333]

The one remaining gear does not have to come off to get the assembly off, the top plate has a hole cut out in it, and this gear remains attached to the mainplate. Removal of this gear, is like any other chrono gear, you need a puller for it.

The biggest "got ya" is trying to get the reset spring to stay in place on the hammer and the lever. If you have the ETA drawings it does help a lot, but even with them, it's a royal pain to get this spring in place, and even more difficult to install the top assembly without having it pop out of place.

Apart from the chrono tilting pinion and autowinder reversing gears and plates on the backside of the movement, installing this assembly is very tedious, and really impossible to type a explanation on, sitting at a bench watching someone do it, straight forward, doing so remotely is hard.

Thank you. This info helped.

When I removed the bridge, I found the hour hammer spring had slipped off the hour hammer operating lever, which released the hour hammer and allowed the white plastic hour counter lock (the component that 'brakes' & stabilizes the hour totalizer hand) to swing away from the hour totalizer gear (I have removed the hour totalizer gear in this picture)

I am assuming the spring had somehow become dislodged while the movement was out of the case (I had removed it to install a gen crown/tube). However, it may also have been dislodged when I first removed the bridge. Because the only other thing that looked different based on ETA's picture of the assembled braking mechanism was the way the k-n-o-b of the plastic hour counter lock did not quite fit all the way into the cut out of the hour hammer operating lever (though everything seemed to function properly when I moved them manually). So I just re-engaged the spring around both the hour hammer operating lever & the hour hammer (in its correct position, according to the ETA drawing)

And then I reassembled everything up to the dial (I only attached the hand for the hour totalizer so I could test it thoroughly before completing the reassembly).

_________

UPDATE - Same problem & now there is a new problem - I cannot operate (push) the top pusher lever at all. It will not budge.

So I disassembled the watch back to where I had reset the spring to see if the spring or one of the other components had come lose and worked itself into the top pusher mechanism. But the spring was still in the correct location and nothing else looked out of place. But even with the bridge and the 8 extra gears removed, I still cannot operate the top pusher (and the hour totalizer is still creeping).

Ignoring the top pusher issue for the moment and concentrating on the hour totalizer issue, the only thing I can see that strikes me as possibly odd is that the hour totalizer gear looks a bit lop-sided when viewed from the side. Because of this, the plastic hour counter lock (which I assume is what keeps the hour totalizer gear from turning when it is not in use) is not making firm contact with the gear's teeth and it is unable to 'brake' the gear's movements (note the gear's lop-sided stance and the way the plastic lock comes into contact with it just under the edge of the gear's teeth)

Does it look like this could be the cause of the hour totalizer creeping? And do you see anything that might account for why the top pusher will not operate (I cannot press the lever in to start the chrono)?

[freddy333]

UPDATE 48 HOURS LATER - I fixed the stuck top pusher problem & half-solved The Mystery of the 'Creeping' Hour Totalizer (the spring comes unhinged if/when you press the lower (reset) chrono button hard.

Now, the reason one has to press the chrono reset button hard is because pressing it normally will only reset the chrono seconds and minutes hands......the chrono hour hand (the one that 'creeps') either does not move or it will only move part of the way back to its null position. You have to keep pressing the chrono reset button harder & harder to get the hand to budge its way back to its proper null position. The Catch-22 here is that pressing the lower chrono (reset) button this hard is what causes the spring to pop out of position, which then allows the hour totalizer hand to start 'creeping'.

None of the 3 chrono reset parts appear to be worn, bent or broken

(Note that this picture was taken with the hour totalizer gear removed & the spring has since been reset to its correct position)

So does Ziggy or anyone else familiar with 7750s know what is causing the lower chrono (reset) button to have to be pressed so hard to fully reset the hour totalizer hand?

[Francisco]

I find this very interesting. Did you solve the problems?

[freddy333]

Yes & no. For this watch, I ended up having to swap out the 4 components (shown in the red circle) that compose the hour totalizer braking system (this system is what holds the hour totalizer gear still when the chrono is OFF) from another 7750, which then fixed the problem. The odd thing is that, just for a lark, I put the parts I removed from the 1st watch into the donor watch & the hour totalizer worked fine. The hour totalizer on both watches was then performing properly. So I am still not quite sure what is going on since I had removed & reinstalled those parts at least 3 dozen times (not an exaggeration) without finding a single thing wrong with any of them. And they were installed into the donor movement in exactly the same way I had repeatedly installed them in the first watch. I was hoping Ziggy might have encountered this before, but I guess not.

Unfortunately, the 'creeping' hour totalizer problem occurred again, a week ago, in this watch. As the watch is currently undergoing evaluation (as detailed in the other thread), I do not want to open the watch again in order to avoid the risk of upsetting our findings regarding the current repair.

[Francisco]

Yes & no. For this watch, I ended up having to swap out the 4 components (shown in the red circle) that compose the hour totalizer braking system (this system is what holds the hour totalizer gear still when the chrono is OFF) from another 7750, which then fixed the problem. The odd thing is that, just for a lark, I put the parts I removed from the 1st watch into the donor watch & the hour totalizer worked fine. The hour totalizer on both watches was then performing properly. So I am still not quite sure what is going on since I had removed & reinstalled those parts at least 3 dozen times (not an exaggeration) without finding a single thing wrong with any of them. And they were installed into the donor movement in exactly the same way I had repeatedly installed them in the first watch. I was hoping The Zigmeister might have encountered this before, but I guess not.

Unfortunately, the 'creeping' hour totalizer problem occurred again, a week ago, in this watch. As the watch is currently undergoing evaluation (as detailed in the other thread), I do not want to open the watch again in order to avoid the risk of upsetting our findings regarding the current repair.

I am beginning to dissambly and "play" with the A7750. Your posts are very interesting. Please, hold on.

[SSTEEL]

I know this is an epic old thread resurrection, but I found it interesting.  I have an issue with a A7750 right now, the hour brake is not slipping, i.e., the hour counter remains still during normal timekeeping, what I am experiencing though is when the chronograph is used, stopped, and then reset, the hour gear moves to random places, and does not reset to 12 as it should do.  Starting and stopping the chronograph, and resetting it each time, it does eventually align to 12, but probably more a coincidence?

 

Anyone know what could be the cause of my specific issue?

[GenTLe]

I know this is an epic old thread resurrection, but I found it interesting.  I have an issue with a A7750 right now, the hour brake is not slipping, i.e., the hour counter remains still during normal timekeeping, what I am experiencing though is when the chronograph is used, stopped, and then reset, the hour gear moves to random places, and does not reset to 12 as it should do.  Starting and stopping the chronograph, and resetting it each time, it does eventually align to 12, but probably more a coincidence?

 

Anyone know what could be the cause of my specific issue?

 

Uhm, What about the reset cam below the hour gear being loose on the hour shaft?

[krpster]

Either that or it is gummed up and prevents proper motion when the cam slides on the reset lever.

[SSTEEL]

Cheers guys, sorted it, the arm was slightly deformed and not making contact fully.