Help With Diagnosis On A 7750 Movement

[DJT2]

OK update Time. 8hrs & a banging headache. Cleaned everything, reassembly was horrible. I'm no fan of working on these movements. However, still showing same problem, I've atleast got it to run OK for about 1 min in beat & +6s/d. Then again it starts to slow & stop, I've demagnetiser twice. I've checked there is still power in the spring & I'm lost now so help would be appreciated.

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[clockboy]

It seems like it is loosing power I wonder if the auto spring is slipping in the barrel. I presume you used braking grease.If all is free then I would have thought it is the only way it would start slowing either by the mainspring not fully winding or just slipping causing it not to fully wind.

[DJT2]

It seems like it is loosing power I wonder if the auto spring is slipping in the barrel. I presume you used braking grease.If all is free then I would have thought it is the only way it would start slowing either by the mainspring not fully winding or just slipping causing it not to fully wind.

New spring & 8217 grease. I've just had a brainwave & thought it could be friction related, so removed the balance endstone jewel & it's still running.

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[clockboy]

New spring & 8217 grease. I've just had a brainwave & thought it could be friction related, so removed the balance endstone jewel & it's still running.

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Might be the cap jewel is upside down. Strange but had that issue this afternoon on a Seiko I had put the cap jewel in upside down & it took a while to suss what was up.

[oldhippy]

Let all the power off, take out the complete balance and pallets then wind a small amount of power to see if the train will run free, if it stops you clearly have something in the wheels that is playing up. If its ok you need to double check everything right down to the mainspring which clockboy has already mentioned. 

[DJT2]

Let all the power off, take out the complete balance and pallets then wind a small amount of power to see if the train will run free, if it stops you clearly have something in the wheels that is playing up. If its ok you need to double check everything right down to the mainspring which clockboy has already mentioned.

Project on hold now as I'm off on holiday. But I know the train is fine & I did replace the mainspring. So when I return I'll start to investigate the balance area

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[Geo]

Project on hold now as I'm off on holiday.

Have a good one!

[DJT2]

Have a good one!

Thanks Geo, I'm just glad I got it all back together. Really didn't want to come home to start the treasure hunt for bits missing on the floor.

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[wls1971]

I may be stating the bleeding obvious but isn't this movement actually a Chinese clone of a 7750, lack of any obvious markings and the fact it runs at 21,600 bph. . If so the spec will be different to a ETA 7750, and as a movement they are bit of a dog when it comes to reliability and time keeping. I don't know if this information has any bearing on how you would service the watch, I don't know enough yet to say.

 

 

 

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[clockboy]

I may be stating the bleeding obvious but isn't this movement actually a Chinese clone of a 7750, lack of any obvious markings and the fact it runs at 21,600 bph. . If so the spec will be different to a ETA 7750, and as a movement they are bit of a dog when it comes to reliability and time keeping. I don't know if this information has any bearing on how you would service the watch, I don't know enough yet to say.

 

 

 

.

Looking at the pics I think you are correct. But because it is Chinese does not mean it won't run (it was running before the service) and it should be possible to service. Hope I am right because the way things are going with Swiss movements we all might as well get used to this dilemma. 

[wls1971]

There's no doubt that some very good movement's come out of china, but I thought it worth mentioning that this particular movement appears to be a early 7750 clone, because if it does require any parts, ETA ones probably wont be compatible.

[DJT2]

There's no doubt that some very good movement's come out of china, but I thought it worth mentioning that this particular movement appears to be a early 7750 clone, because if it does require any parts, ETA ones probably wont be compatible.

Yes you are correct about the origin of the movement. I believe my friend got it on holiday a few yrs back & I can tell you that's it's nowhere near the quality being produced right now in China. However, as clockboy states..it ran before & therefore it should again. As for parts.. until I can find the problem, I can't find a solution.

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[steven]

Might be the cap jewel is upside down. Strange but had that issue this afternoon on a Seiko I had put the cap jewel in upside down & it took a while to suss what was up.

Placing cap jewel upside down can be a solution in some cases. I learned this trick long time ago from an old watch repairer.

So happen this week I've been working on two old watches with bad timegrapher reading on one side although the balance wheel pivot is not broken. After placing the cap jewel upside down on the problem side of the balance wheel, the reading on the timegrapher has improved in one and normal in another.

I know the trick is not acceptable to professional watch maker but it works when replacement part is hard to get.

DJT2, as an experiment, you may try this trick and see if it helps.

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[DJT2]

Placing cap jewel upside down can be a solution in some cases. I learned this trick long time ago from an old watch repairer.

So happen this week I've been working on two old watches with bad timegrapher reading on one side although the balance wheel pivot is not broken. After placing the cap jewel upside down on the problem side of the balance wheel, the reading on the timegrapher has improved in one and normal in another.

I know the trick is not acceptable to professional watch maker but it works when replacement part is hard to get.

DJT2, as an experiment, you may try this trick and see if it helps.

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Good tip Steven, when I'm home I'll be giving it a try.

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[Louie]

It is my first post in this forum, but I hope I can help out.

 

The solution of your problem is shown on the picture of the movement breakdown. This A7750 has a additional module which redirects the second from the 9 to the 6. These modules are ill constructed and prone to failure. Just assemble the movement but leave the module off and you will finde out that the movement will run great. (at least I hope) The only lasting cure for this module is to remove one of the wheels and so killing the sec at six. It is a well known Problem with replica watches like the Daytona.

 

Excuse my English, I'm not a native speaker.

[DJT2]

It is my first post in this forum, but I hope I can help out.

The solution of your problem is shown on the picture of the movement breakdown. This A7750 has a additional module which redirects the second from the 9 to the 6. These modules are ill constructed and prone to failure. Just assemble the movement but leave the module off and you will finde out that the movement will run great. (at least I hope) The only lasting cure for this module is to remove one of the wheels and so killing the sec at six. It is a well known Problem with replica watches like the Daytona.

Excuse my English, I'm not a native speaker.

Hi louie & welcome. TBH I've been meaning to update this thread for a while, but time has been my enemy. The movement is currently in my box of must do movements & I'm sure I'll take another crack at it within the next few weeks. But thanks for the insight regarding seconds @6.

Now I'm employing a different cleaning process & using different chemicals. I'm hoping I may see a different result.

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[bobm12]

Hi Louie,

 

Welcome to the forum and thank you for sharing valuable advise. We hope you enjoy it as much as we do!

 

Cheers,

 

Bob

[Louie]

Hi louie & welcome. TBH I've been meaning to update this thread for a while, but time has been my enemy. The movement is currently in my box of must do movements & I'm sure I'll take another crack at it within the next few weeks. But thanks for the insight regarding seconds @6.

Now I'm employing a different cleaning process & using different chemicals. I'm hoping I may see a different result.

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I don't want to discourage you, but you won't get the module to work at least not in the long run. There are iircr about 5 additional wheels which are suppose to transfer the second to the six. There are no additional jewels to reduce drag.

 

The movement is just not strong enough to turn the wheels. Our chinese friends even avoid to properly oil the movement due to the fact that oil introduces additional drag on the wheels thus reducing the available power even further. Try to run the movement without the module on the timegrapher and note the amplitude, then mount the module. You should see a hugh drop in amplitude.

I tryed also different things and only a dry module (no oil or whatsoever) kinda worked for a while.

[DJT2]

I don't want to discourage you, but you won't get the module to work at least not in the long run. There are iircr about 5 additional wheels which are suppose to transfer the second to the six. There are no additional jewels to reduce drag.

The movement is just not strong enough to turn the wheels. Our chinese friends even avoid to properly oil the movement due to the fact that oil introduces additional drag on the wheels thus reducing the available power even further. Try to run the movement without the module on the timegrapher and note the amplitude, then mount the module. You should see a hugh drop in amplitude.

I tryed also different things and only a dry module (no oil or whatsoever) kinda worked for a while.

Thanks again Louie, I did try the movement without the module & I was still seeing poor results. It still stopped when I flipped the movement Dail side up etc.. However, I do believe I've narrowed the problem down to the balance & I've been waiting to get a donor movement to try different balance bridge/assembly etc. I've now got the donor & once everything is recleaned, time permitting I will take another look at it over the coming weeks.

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