Shanghai B SB1ZZ 23 & 35 jewel question?

9141 Views 6 Replies 4 Participants Last post by lysanderxiii, Sep 5, 2008

gigfy

Discussion Starter · Sep 1, 2008

Hey guys,

I've been looking around for a GMT and finally found one without the usual mercedes hands. I had seen them on eBay but didn't really look closely at this one until Dapper posted a pic of his ChronoMat / ChronoTac. I've read before that the Alpha GMT uses a 23 jewel Shanghai B and the ChronoTac advertises that is also uses a 23 jewel movement. They look awefully alike to me. But in the review by Highoeyazmuhudee, his ChronoTac has a 35 jewel SB1ZZ. Are these the same movements? Where did the 23 jewel number originate?

Check out these old posts and let's see if we can come to a conclusion about these movements.

Alpha GMT movement disassembly

ChronoMat / ChronoTac GMT review

Alpha

ChronoMat / ChronoTac

Cheers,
gigfy

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soviet

· #2 · Sep 2, 2008

Hi gigfy,

I think these are the same movement that is based on Diamond "B" thin movement with 17 jewels. The economy 23 jewels movement added 6 more additioanl jewels for the automatic component. The 'luxury' 35 jewels version has more jewels on the automatic mechanism. The two small wheels each has 5 jewels, but I am not sure where are the other 2 jewels. Maybe for the main spring plate?

Regards,

Soviet

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Chascomm

· #3 · Sep 2, 2008

The Alpha that was disassembled in that article was in fact a 35 jewel version:

Now I think about it, I don't recall ever having seen any close-up movement pictures of a genuinely 23 or 25 jewel B. Perhaps there really is only one version, labelled variously for some obscure reason (like Alpha's "7 JEWELS" ST16s)

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gigfy

Discussion Starter · #4 · Sep 2, 2008

Thanks Guys! :thanks :-!

I thought they were the same, but I just wanted to be sure.

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lysanderxiii

· #5 · Sep 4, 2008

There is another four-handed movement available, perhaps, early versions were fitted with this?

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Chascomm

· #6 · Sep 5, 2008

I believe that's a Guangzhou DG-28 derivative. I've only seen the GMT version is more recent watches, but who knows how long it's been around really?

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lysanderxiii

· #7 · Sep 5, 2008

In some of the ebay pictures I saw that movement in Chrono-Tac (Chronomat) GMTs with the semi-exposed auto-wind wheel red teflon coated to resemble the Rolex movements.

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