noob 7750 questions

[debian 0]

Has New Asia Valjoux 7750 (28,800bph) a working cronograph?

for example this

what does 28,800bph mean?

[Luthier 1]

Has New Asia Valjoux 7750 (28,800bph) a working cronograph?

for example this

what does 28,800bph mean?

 

All 7750 has chrono function.

28,800 beats per hour. High beat movement. Low beat movement, like 21j, has 21,600 bph.

The seconds hand on high beat movements moves much smoother.

[greg_r 81]

Yes. The 7750 is indeed a chrono movement, although is also sometimes used for non-chrono watches as well. 28,800 means that the second hand 'ticks' 8 times a second making the sweep of the hand very smooth. The older version of that movement swept at 21,600 which wasn't quite a smooth.

[Rav747 0]

Ok, so one should stay away from watches that have 21j movements? or are we just talking about smoothness and not accuracy?

[greg_r 81]

21Js are inexpensive and mostly fine. It's the visual sweep of the second hand that it noticeable, but they can still keep good time. Do bear in mind, however, that a 21J is NOT a chrono movement - if you see a chrono watch (such as, say, a Daytona) that has a 21J, those subdials are going to be faux and will not work like the gen...

[RolexAddict 1]

The called "old" version, 21j-21.60bph, is in fact the real clone of the Valjoux/eta7750. Swiss and Chinese clone parts are mixable. This movement is 100% reliable.

 

Problems with the A7750 28.800bph :

The called "Improved" version, 29j-28.800bph, is a Chinese product, they tried to improve the 21.600bph adding jewels and modifying some parts. This movement is problematic as he dies randomly. Some says its the fact of the sec. at 6 complication made to copy modern Daytona. This is vrong.

Problems come from the mainspring in the cylinder who collapses lot of time, and from the bad design of the new balance assembly and escape wheel design.

Edited June 5, 2010 by RolexAddict

[debian 0]

I have another noob 7750 question...

What does hack movement mean?

 

Example here:

http://www.asian7750.com/cn/product_show.a..._id=425&ti=

[greg_r 81]

'Hack' refers to a movement where pulling out the crown to the hand set position stops the second hand in order to enable setting of the time to the exact second. It was originally a military term, I believe.

[Rav747 0]

21Js are inexpensive and mostly fine. It's the visual sweep of the second hand that it noticeable, but they can still keep good time. Do bear in mind, however, that a 21J is NOT a chrono movement - if you see a chrono watch (such as, say, a Daytona) that has a 21J, those subdials are going to be faux and will not work like the gen...

A lil late of a reply on my end, but thanks