Watch running fast after rebuild including changing balance cock/wheel

[lee1979]

Hi,

I just finished rebuilding my watch (first one), and everything is working fine, except the watch is running very fast. Takes about 45 seconds for the second hand to go around. The watch is a Tissot ETA-2846 movement.

I replaced the whole balance cock/wheel/spring with a new one during the rebuild.

Is it likely I just need to adjust the balance spring?

I tried demagnetizing the watch but didn't make any difference.

The attached photo is the balance. Would I just move the gold colour adjuster anti-clockwise to lengthen the balance spring?

Also, what does the screw next to the +/- do? It didn't seem to make any noticable difference.

Thanks

Lee

Edited November 28, 2023 by lee1979

[Nucejoe]

Are you sure the new balance complete has the ferquency your watch needs ? 

Aparently the new balance complete is  28800 beater whereas your watch needs a 21600 beater, 

21600÷ 28800= .75

45÷60= .75 

3 hours ago, lee1979 said:

is  it likely I just need to adjust the balance spring?

No , that wont do it. 

Rgds

4 hours ago, lee1979 said:

 what does the screw next to the +/- do? It didn't seem to make any noticable difference.

Thats your micro adjustor.

 

[JohnR725]

4 hours ago, lee1979 said:

Tissot ETA-2846

Maybe a little more detail here? The reason I ask is often times Tissot isn't exactly the same it's possibly been modified or changed so is that the number under the balance wheel engraved on the main plate? Then sometimes you get like a -2 after the caliber number and of course that will change things.

4 hours ago, lee1979 said:

I replaced the whole balance cock/wheel/spring with a new one during the rebuild.

Then out of curiosity why was that done what happened to the original one? Plus we do like pictures but pictures of the balance wheel out of the watch Are not helpful in that the problem is the balance wheel in the watch. So for instance the picture you have you definitely have problems as they hairspring isn't properly centered it looks like it's touching that would make it run fast so we need a picture the balance wheel in the watch so we can see where they hairspring is and if adjustments have to be made or not.

 

[lee1979]

thanks @Nucejoe

That is exactly it. My mistake. I bought a complete balance for 2836 because I couldn't find one for 2846 (as per my previous thread, I damaged a chaton and bought a whole new balance as a I couldn't find the chaton on its own). I thought that most of the parts were the same across 2836 and 2846, but I guess I was wrong at least on this one.

I found these pages now, which confirms that the beats are exactly as you say, so explains the 45 seconds vs 1 minute.

https://calibercorner.com/eta-caliber-2836-2/

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&ETA_2846

Is the chaton in the new 2836 balance likely to be the same as in the 2846 so I could put the old balance wheel back on with the chaton from the new balance?

Thanks

Lee

[JohnR725]

I have a link to where you can find a parts list for each of your watches. Then you can click on the part that you're interested in and it will cross reference with all the watches that have the same part.

 

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=ETA_2846

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=ETA_2836-2

 

[Nucejoe]

Hi Lee, 

14 minutes ago, lee1979 said:

https://calibercorner.com/eta-caliber-2836-2/

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&ETA_2846

Is the chaton in the new 2836 balance likely to be the same as in the 2846 so I could put the old balance wheel back on with the chaton from the new balance?

Notice, Dr ranfft lists  11.5 "'  for both eta 2836 and 2846 , based on which I say yes chatons are the same for both calibers. 

 

[lee1979]

Thanks, @Nucejoe. That's good news at least.

Just when I thought I was done with the balance wheel and shock-absorbers!

[Nucejoe]

 Hi Lee, 

Base movement of ETA 2824 and 2836 are entirely interchangeable, and both calibers are most common of ETA's , so your next project can be either of said calibers in need of balance complete. 

Rgds

[lee1979]

4 hours ago, Nucejoe said:

 Hi Lee, 

Base movement of ETA 2824 and 2836 are entirely interchangeable, and both calibers are most common of ETA's , so your next project can be either of said calibers in need of balance complete. 

Rgds

Thanks, @Nucejoe.  Might wait a little while until I embark on the next one, but good idea!

[lee1979]

Just a quick reply to let everyone know that I managed to get a used 2846 balance and finally finished rebuilding the watch yesterday. Seems to be running pretty perfectly at the moment. I still need to measure it properly and maybe make some minor adjustment, but it was still on the correct minute after running for a day or more.

On to the next one!

Thanks for all your help!

Lee

Edited December 9, 2023 by lee1979

[rossjackson01]

Good the members aren't they?