chronograph friction problem

[wtchgk]

I have encountered the following problem on more than one A7750 and I wonder if watchsmiths have found whether there is one single culprit that is mostly causing it.

When activated, the chronograph stops right away and stops the movement with it. When I shake the watch, it may run for a minute but then it stops again near the starting point. If I loosen the screws of the automatic device bridge a bit the chronograph runs fine.

 

[R2D4]

Sounds like your problem is...

1. You took the watch apart and tried your own self diagnosis.
2. You took the watch apart and tried your own self diagnosis.

lol

Send it out to a Pro. I have had a few watches such as yours and I still haven't learned this lesson. Learn from me. Do it yourself and spend.

Good luck.

 

[Targa]

Is you have to loosen up something to make it run then
1. the watch needs service because it is dry
2. the watch needs service because it is dirty
3. the watch needs service because something aint right

I was lucky enough on my last attempt at modding that I hadnt FUBARED the watch with the Swiss movement and Katt was able to get it working despite my being inside there

Since you have a 7750, sent it to G...on this forum PM.. 14060 or 16610? or email [email protected] for assistance

 

[levelmanroger]

It almost sounds like you are trying to run the chrono without a strong power reserve. I assume you know to make sure the watch is nearly fully wound before running the chronos?
Otherwise, a good professional service is in order.

 

[AstroAvia]

It seems to me like your tilting pinion is causing the problem. I would remove the clutch spring, then activate the chronograph and observe what happens. Then, with care and attention, I would play with the clutch 60s using a small screwdriver to act upon the tilting pinion until it engages with the chronograph wheel and, again, observe what happens.

 

[wtchgk]

Thank you very much for your replies. I am well aware that a service will mostly likely solve the problem, but I am really curious about possible failure mechanisms aside from dirt and improper lubrication.

In case you want to know, I eliminated the column wheel (oszillating pinion) and clutch as the cause. So it seems that maybe not enough power is being generated and/or there is too much chronograph wheel friction. The parts driven by the chronograph wheel move freely. I do have a feeling that the main spring is contributing because I can wind it for a long time without ever feeling strong resistance.

However, you may also be interested in hearing what triggered all this in the first place. By now I received several watches that either were DOA or only partially working. All came from trusted dealers that claim to do good QA and I am reasonably confident that besides sending pics they test at least all functions of the watches before they ship. So what happens during transit that causes these watches to fail? In one case I found that a moving and a non-moving part were 'baked' together and stopping the watch. My best guess is that this was caused by exposure to extreme heat (120+F/50C) during transit in the Southwest US.

 

[AstroAvia]

Back when I ordered my first replicas from very reputable dealers, I had nothing but bad luck - let's put it this way. Not one single watch bought brand new from the dealers was OK on arrival. From incorrect straps to glued caseback screws, including broken screws stuck inside the movement of a watch the dealer himself told me he'd been wearing for one week before sending it to me - because he liked the watch so much!!

I don't believe that damage in transit responds for so many DOA watches. I believe the dealers do send bad items randomly, depending on who the buyer is and whre he is located.

Back on topic. I would now check the wheel friction. It is inverted, maybe?

PS: column wheel and oscillating pinion are not synonyms, i.e., they're not the same part.

 

[wtchgk]

Back on topic. I would now check the wheel friction. It is inverted, maybe?

This check will have to wait. Once I start taking off hands I want to have enough time and be prepared to do a full service. But I shall report back.

And thanks for pointing out the part naming error. I used the same text to respond to someone else who had called this part the column wheel.

 

[AstroAvia]

No need to take all the hands off. Remove the automatic device bridge and the next couple of parts, then you'll be able to see the friction. If it is inverted and/or out of place, you can remove and reinsert the friction without removing the chronograph bridge. In this case, all you have to do is to remove the chrono seconds hands and take the chrono wheel off.

 

[wtchgk]

No need to take all the hands off. Remove the automatic device bridge and the next couple of parts, then you'll be able to see the friction. If it is inverted and/or out of place, you can remove and reinsert the friction without removing the chronograph bridge. In this case, all you have to do is to remove the chrono seconds hands and take the chrono wheel off.

I finally got around to completing this repair. First, the chrono wheel friction was not properly seated. But then I found that the hole or the bearing for the oscillating pinion in the clutch was far too big, i.e. the pinion was wobbling. This could not be solved with the excenter adjustment and I finally replaced the clutch. The chrono is now running perfectly and smoothly as it should.

Thanks again for your comments and suggestions.