Eta 900 timegrapher trouble shooting

[praezis]

Last photo: Imho these are totally different balance wheels.

Frank

[Nucejoe]

So putting the hands on and bench timing , gives the only data with excellent degree of confidence. For all we know, despite running this new balance might not be right one for the watch.

We can't count on TG either, it shows 18000 when set manually and in 7-8 seconds switches back again.

[JohnR725]

5 hours ago, praezis said:

Last photo: Imho these are totally different balance wheels.

yes physically there different but they hairspring is have a similar look? There doesn't appear to be much of a terminal curve? I would really like to see the balance wheel in the watch with a close-up picture aimed at the hairspring regulator pins?

[Nucejoe]

If the new oscilator actually beats 19800 it would run the 18000 beat train fast which is what the first tg reading indicate, but OP reports the watch running either slow or really late and( I am not sure I understand what he means by really late). 

Watch runs with the new oscillator so we have escapement but if this oscilator is a wrong one and so is the new roller table  then impulse should be imperfect and  OP should not see a happy running watch, I mean it can run but not happy.

I sympathise with OP, all data has remained inconclusive. I think a bench timing will shed some real light.

 

 

[rodabod]

Perhaps take some more photos as John suggests, to show if it is mounted correctly. A slo-mo video can also be handy. 
 

I’m surprised that the balance diameter is different, but the fact that it sort-of-runs suggests it could be correct. Do the rollers look like they have similar proportions?

[GaspardColigny]

I will take some more photos with the balance mounted. I will have a look at the roller jewels as well.

@Nucejoe it runs 45 mins fast in 6 hours, so about 3 hours over a full day.  That ratio 24/27 = 0.89 is very close to the ratio of the bph: 18000/19800 = 0.91.

[Nucejoe]

15 minutes ago, GaspardColigny said:

I will take some more photos with the balance mounted. I will have a look at the roller jewels as well.

@Nucejoe it runs 45 mins fast in 6 hours, so about 3 hours over a full day.  That ratio 24/27 = 0.89 is very close to the ratio of the bph: 18000/19800 = 0.91.

Wrong balance complete then. 

Can be a case of modified caliber of its family/ generation. 

No use wasting time on this one, you should get the right balance complete.

Best wishes

 

[GaspardColigny]

I've ordered a new balance, which has the same measurements as the original, fingers crossed.

[GaspardColigny]

The new balance had similar dimensions as the old one, and upon installing it, proved to be the correct balance. Timegrapher shows +6, around 290 amplitude and the BE is 0.4. so very chuffed. The Eta 900 is now ticking away happily in the first watch I've completed: this late 40's, early 50's Stowa, with an immaculate dial. 

 

[Nucejoe]

I see why you like this watch, a nice classic look, enjoy it in good health.

Surely you know, that old balance can be vibrated with a compatable hairspring to produce the right frequency, lots of fun without a vibrating tool though. 

Regards joe

[GaspardColigny]

34 minutes ago, Nucejoe said:

I see why you like this watch, a nice classic look, enjoy it in good health.

Surely you know, that old balance can be vibrated with a compatable hairspring to produce the right frequency, lots of fun without a vibrating tool though. 

Regards joe

Thanks, vibrating hairsping and balance...in due time perhaps haha.