Help - A7750 minute totalizer moved

[freddy333]

What is the trick to repositioning the minute totalizer on an A7750 (the hand is NOT loose)?

I removed the rotor & auto-wind gearing on an A7750-powered 6263, but, upon reassembly, I found the minute totalizer was resetting to -59 minutes instead of its normal null position at 12. So I unscrewed the 3 screws & removed the auto-wind bridge again to check the positioning of the minute totalizer assembly. Everything was in its correct reset position

So I reinstalled the bridge, but found that the minute totalizer had moved again into this position

What gives?????

It may be difficult to see, but the hammer is properly contacting the heart-shaped gear on the minute counting wheel (the yellow colored wheel near 6 o'clock in the 1st pic), which is what sets the minute totalizer reset position. So it ought to reset to 12, but does not.

As we all know, the subdial hands on these watches are notorious for coming loose on their tubes & then resetting in different positions. So the 1st thing I checked was the hand. Perfectly tight, no play (in any direction) whatsoever. (The hand is NOT the problem.)

So, again, I removed the auto-wind bridge & checked the positions of the chrono components, but everything looks fine.

Am I missing something?

How did the minute totalizer hand move from its normal null reset position if everything in the chrono assembly appears to be normal & how do I get it to reset back to 12?

I apologize for the less than clear pics. I am currently without a macro shooter.

[FxrAndy]

As far as i know, it can only be the hand, the only other thing and i have never known it is that the pinion is loose in the gear?

[vlaletom]

seams like you really have a weird problem.

as you are shure the hand doesn't move on the pinion (i guess you tried to block thee weel whether by hand or with rodico) it has to be somthing with the reset hamer.

if i get it wright the hand is now allway resting between 15 & 16 mnts ? or does it reset randomly ?

when you push the hammer by hand the hand ends up at 15 or at 0 ?

i mean it could be that the wheel reset corectly, but that it doesnt get really blocked because the arm dont put enough pressure after it hit the cam and so the weel can freely bounce to 15?

But i guess you allready checked that ...

for what i see in the first picture the 6 oclock wheel wich recive the hammer contact is not the real minuts counter wheel (the one with the hand pinion) or the hand would sit at 12 (since the watch picured is upside own)

So can't it be that this reset wheel has to engage the hand pinion thrue various other wheel, and so has to be engaged to the the exact minuts reset position (i mean that the wheel theeth have to be engaged in 1 and only 1 position)

Sorry else than that i dont see.

You probably need a better answare from somone more competant with this movement ...

[FxrAndy]

Another possibility

It could also be as this is a modded 7750 to tricompax lay out that the gears that have been transfering the drive to the new location have alowed the end gear under the 3 possition to slip round while the watch was up side down. If you reset the hand it should be fine, but i would wonder about the free play between the modification plates.

[ubiquitous]

If it's a tolerance issue with the transfer gears, it should be fairly easy to confirm, I'd think? Just flip the watch dial side down and see if the hand moves to another position? However, if the gear itself has slipped out of place, resetting via the pusher will only reset the hand to where ever the gear had settled and re-meshed last, I'd think.

This is a strange one, indeed, Freddy.

[TeeJay]

I'm no expert on movements at all, but, my instinct would be as Andy has suggested, that the issue (visually speaking, even if not mechanically) is the hand itself. If the gears are all correctly located inside the movement, I would suggest removing, and re-installing the hand so it is properly aligned, and seeing if that corrects the problem I hope you get it worked out

[freddy333]

Thanks for all of your input.

It is hard to explain how the minute totalizer gearing is configured on these secs-at-9 7750s (these do not have the additional (inherently problematic) relocation gearing of the modern Daytonas), but the yellow wheel in my pic is connected to another wheel on the bottom of the movement (below the dial) that runs in tandem with it (this is the wheel the hand is connected to). I found that there is a small amount of free-play between these 2 wheels that occurs only when you remove the auto-wind bridge. Why? No idea. But I also found that if I gently lift the yellow wheel while turning it, part of the turning motion would transfer to the other wheel, while part of the turn would not. So, after I figured this out, by trial-&-error, I was able to reset the difference between the 2 wheels so that when the yellow wheel is in its proper null/reset position & the minute totalizer hand was also pointing to 12