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After reading Mike/Polly's tutorial on how to overhaul your 6139- Chrono, and the warning to be careful with substituting 6139A movement parts with a 6139B movement, I opened my 2 6139 chronos to see what I had.

One is marked "6139A 17 Jewels" (non-working). The other reads "6139A 21 Jewels" (works but needs an overhaul just because I want it to).

How can there be different jewel counts in the "same" 6139A movements? Most importantly, if the watchmaker has to rob a part from the 17J movement to really make the 21J units top-notch, will he be able to do so?

Any help to enlighten me on this confusing finding will be greatly appreciated !
 

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There are different jewel counts because the 21j model has jewels in place of bushings in four places. The plates and parts of the two "A" movements are entirely swappable. A's & B's are not for the most part, especially the train bridge, chrono wheel, chrono bridge.
 

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Spencer said:
There are different jewel counts because the 21j model has jewels in place of bushings in four places. The plates and parts of the two "A" movements are entirely swappable. A's & B's are not for the most part, especially the train bridge, chrono wheel, chrono bridge.
:iagree: :iagree:
 

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spidefunk said:
Ahhh..nice info, maybe 6139 21j is jdm and 17j for international market

That's correct :)


Take heed to Spencer's advise re; parts interchangability vis a vis A/B revisions, comparison of the parts numbers will reveal that there are quite a few different ones.
 

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Discussion Starter · #7 ·
Mike & Spencer,


You guys are Awesome - Thank You !


I lucked out I guess that these are both "A" movements, and the extra jewel count does not harm the interchangeability aspect (for the most part).


Thanks!
Jon
 

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GrammarOfDesign said:
Mike & Spencer,


You guys are Awesome - Thank You !


I lucked out I guess that these are both "A" movements, and the extra jewel count does not harm the interchangeability aspect (for the most part).


Thanks!


Yes, they are.


Too, I think the 21J 6139A movement is "rarer" than the 17J movement, from what I've read.


Dan
Jon
 
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