Technotime TT651 Module Technical Documentation

[mzinski]

Hi, 

I have a Bell & Ross BR03-51 GMT carbon fiber watch with a date disc that keeps coming out of alignment. It appears the wheel between the two large date discs has two broken teeth and will need a replacement part. But for the life of me I cannot find information (via the internet) on the technical documentation of this movement. It’s a modified ETA2892 with a Technotime TT651 module on top. 
When I realign the date discs, they flip and align fine - I’ve quick date set for about 6-months of date changes. It must be the date driving wheel interacting with those broken teeth that cause the issue. 
Anyways, if anyone can help with documentation so I can attempt to order the part from someone (somewhere) it would be greatly appreciated! 
TIA! 

[clockboy]

I have not been able to find any docs including the ETA 2892. However the way forwards will be to find a donor movement. 

[watchweasol]

Hi   The documentation on TT movements is very thin and that I have mention replacement movments, as Clockboy says a donor movement is the way to go

[jdm]

8 hours ago, mzinski said:

It’s a modified ETA2892 with a Technotime TT651 module on top. 

Anyways, if anyone can help with documentation so I can attempt to order the part from someone (somewhere) it would be greatly appreciated! 

If Technotime is like Dubois Depraz or Bell&Ross is like most other Swiss makers, they will not sell parts to anyone. You can, of course, contact them directly as a "qualified independent watchmaker" and try your luck.

Edited March 18, 2020 by jdm

[nickelsilver]

Can you show more of the mechanism? I have a sneaking suspicion that those teeth are missing for a reason. Both discs only jump at the same time on some jumps, on others the left hand one doesn't. How that works remains to be seen.

[mzinski]

On 3/18/2020 at 4:18 AM, nickelsilver said:

Can you show more of the mechanism? I have a sneaking suspicion that those teeth are missing for a reason. Both discs only jump at the same time on some jumps, on others the left hand one doesn't. How that works remains to be seen.

I had the same suspicion as you! But ended up doubting my instincts because I fixed this once (dates were out of sync). Checked it. Reassembled. And a month later the dates were out of sync. 
on closer inspection, this wheel is actually two wheels stacked. Both with appropriately missing teeth to allow either date disc to flip at the right time. 
So, in the end, I don’t think (right now) I need a new part. What I need to do is solve why this reoccurred. 
here’s the extra pictures. 

[nickelsilver]

Ok!

To me it looks like there is quite little room between the wheels in the stack, and the wheels are quite thin; my first thought is that the discs may have a hair too much play on their tenons, and be tilting during a jump sometime, either causing a misjump or making one jump that shouldn't. Could we see what the underside of the discs look like? Another possibility is jumper tension; I think the discs are in engagement with the wheel stack in general, except when on a 'missing tooth' time, if the jumper tension is too light, or again if there is some play and the discs can come out of engagement with the jumper, then you'll go out of synch. Of course if the jumper tension is too high, you'll lose amplitude or stop the watch...

Edited March 19, 2020 by nickelsilver

[jdm]

7 minutes ago, nickelsilver said:

Of course if the jumper tension is too high, you'll lose amplitude or stop the watch...

What is the normal amplitude loss when a calendar or crono module rides on the like of  a 2892?

I didn't had a chance yet to work on those. 

[nickelsilver]

10 minutes ago, jdm said:

What is the normal amplitude loss when a calendar or crono module rides on the like of  a 2892?

I didn't had a chance yet to work on those. 

Ha, I honestly don't know, but I think it is practically nothing. The date wheel takes a while to pull the date disc around. On some watches with instantaneous systems you might see 5-10 degrees drop while it's arming the system.

[mzinski]

On 3/19/2020 at 9:32 AM, nickelsilver said:

Ok!

To me it looks like there is quite little room between the wheels in the stack, and the wheels are quite thin; my first thought is that the discs may have a hair too much play on their tenons, and be tilting during a jump sometime, either causing a misjump or making one jump that shouldn't. Could we see what the underside of the discs look like? Another possibility is jumper tension; I think the discs are in engagement with the wheel stack in general, except when on a 'missing tooth' time, if the jumper tension is too light, or again if there is some play and the discs can come out of engagement with the jumper, then you'll go out of synch. Of course if the jumper tension is too high, you'll lose amplitude or stop the watch...

Here’s a few more pictures. I toyed with the tightness of the springs. The date flips with a secure “snap”. Looks very good to my eye. I’ll test this against the Timegrapher to see if there is a dip in amplitude - and report what I find.