7750 Shanghai big problem

[flannel77]

Hi every boby,

I bought a 7750 Shanghai.

So, I can say :

- parts are really very dirtys

- no oil anywhere

- finitions are really poor. Parts are very poor quality

- second hand (chrono) for 7750 (0,25 mm diameter) don't fit on it. 0,25 mm diameter is too large. I think it's probably 0,20 or less and I don't find second hand who fit well with my dial

No surprise for 120 bucks but really too expensive if one can use it !

Anyway, my problem :

I didn't check timing before servicing it. I have done a complete servicing and refinishing parts.

Timegrapher say : 28800 BPH, lift angle 49°, Rate +2 seconds, beat error 0,2 and amplitude not so good at only 220.

Balancer seems visually very very good

AND the movement take + 20 minutes per hour !!!!!!!! It's crazy. If I fit the balancer at - 200 seconds/day, the movement take always 1H30 for a night...

I'm really desapointed with that movement !!!!

If one have a good idea it will be great

Thank's a lot for that

[RichardHarris123]

1 hour ago, flannel77 said:

AND the movement take + 20 minutes per hour !!!!!!!! It's crazy. If I fit the balancer at - 200 seconds/day, the movement take always 1H30 for a night...

Sorry I don't understand this. 

[nevenbekriev]

You just need balance for 21600 for this movement. There is slight possibility the hairspring to be effectively shortened due some foult, but most probably You movement has been completed with wrong balance.

[flannel77]

Thank's for your reply.

Yes, you re right. I think there is a wrong part somewhere because today I saw something more strange . Hour take +/-15 for an hour BUT chrono run well and keep time !!!!!!!!!

So I don't think it's a problem with balancer.

Perhaps a wheel !?

It's crazy

[flannel77]

Find it !

I think seller (ebay) was not honnest with me.

I check all the wheels with attention. Every parts on this movement are in shiny brass with poor finish except one wheel who is matte and cery well finish. It's the second wheel (this wheel support the little second hand too). I'm sure this wheel is not oem and this perfectly explains the problem of discrepancy between chronometer and watch. Perhaps an ETA wheel.

I think this movement was repared before I buy it. I suppose this wheel have not the same number of teeth that oem part. Very similar but not exactely the same. And it's why the chrono keep time but not the rest of the watch. It's an evidence. If I run the chrono for 1 minute, chrono keep time but the little second hand take approximately + 10 sec for 1 minute !!!!!

It can only be a question of a wheel with a wrong gear ratio !

This also means that the wheels train is not identical between Eta and Shanghai

This also means that this movement is not usable for me today because there is no oem spare parts for it and no chrono hand.

Happy !

So, Shanghai vs Eta :

+/- 120 euros vs +/- 400

more ship but parts not identicals.

no spare oem parts so you need to buy another one if problem

poor quality, finish, very dirty, no oil

diameter of chrono hand is not identical too (0,20 vs 0,25 diameter). I need a 17 mm chrono hand for my dial, and I don't find it anywhere.

In the end this movement is really not a good deal !

 

Everything is said, I think !