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How to remove an Asian 7750's calendar mechanism?


lhooq

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I recently ordered from DW three Asian 7750 movements, to be used in his own Daytona cases. These movement have the required 3-6-9 layout. Unfortunately, they also have an unnecessary day/date complication, which makes the movement (minus the rotor) too thick for the case.

According to DW, it should be a straightforward job for a watchmaker to remove the date mechanism. I brought one of these movement and a DW Daytona case to my watchsmith, and asked him to make it fit. Several days later, and he still couldn't figure it out. He has experience with a wide variety of movements (heck, he even got the chronograph of my Cal.12 running again), but the 7750 (especially the Asian version) gives him huge headaches.

Ideally, I would like to return all three movements to DW, but his current level of communication is much flakier than usual. Is there a trick to deconstructing the A7750 that I can relay to my watch guy, or is this a much harder job than DW implied?

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There's a PDF floating around with all of the parts laid out in exploded form. I think the train is held in by three screws

I've had this ETA service guide in my HD for a while. TIme to make some printouts and tell my 'smith to try again--and try harder!

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The calendar plate is shown here:

BottomPlateWithCalendarDscn0744.jpg

it's held on by three screws. Remove the date disc in the usual way, then remove the screws (around the edge) and the whole thing should lift right off.

Remove them and you're left with this

BottomPlateCalendarRemovedDscn0771.jpg

3 and 4 need to be removed. As long as what DW gave you will hold the parts labelled 1 and 2 (hour totalizer and the brake) in place you should be fine.

Should be pretty straightforward for a watchsmith.

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But with out the date plate on the hour totalised and brake are not held steady and will just fly off when touched, also by removing this plate the the canonpin, hour wheel and seconds pinion will be too long and so will the totaliser pinions, i have a DW 369 in my spares box i will take a photo of what it looks like dial side.

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But with out the date plate on the hour totalised and brake are not held steady and will just fly off when touched, also by removing this plate the the canonpin, hour wheel and seconds pinion will be too long and so will the totaliser pinions, i have a DW 369 in my spares box i will take a photo of what it looks like dial side.

Well I assumed that the parts DW supplies consist of some sort of plate to hold the 12->3 transfer gears, that sits on top of/replaces the calendar plate... otherwise I don't see how it could work.

interested to see the pics

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Here, step by step to disassemble the classic day/date 7750 with 12, 6, 9 subdials

http://pugwash.info/eta/7750/7750.html

the you will need the Chinese modification, allowing to transfer the minutes counter at 3 instead of 12. It consist of a round plate hold by 3 screws, this is a module, with a "bridge"

you need this module, I don't know where you can find it, except if a rep daytona modified 7750 is canibalized

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Thanks, everyone, for the valuable input. DW has sent me an email, so I can return the movements to him. However, I'd like to investigate this further before I do.

Here are pictures of the movement in question, starting with a close look at the combined calendar/transfer plate:

i-9HbDZD7-L.jpg

i-LhkTSQw-L.jpg

Same thickness as other A7750s?

i-xkVd6B7-L.jpg

Stem height:

i-H3pn9jS-L.jpg

Bottom:

i-ZRX8vb8-L.jpg

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And you say it is too thick?

From the side, the movement height appears to be identical to your no-date A7750, other than the ring that surrounds the datewheel.

If that ring is removed, it makes little difference to the overall movement height because the transfer gears in the center are almost at the same level as that ring.

dw2.jpgi-xkVd6B7-S.jpg

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  • 2 weeks later...
That is exactly the same movement I got from DW. Were you able to have your watchmisth remove the Date wheel carrier ok M? I'm working on installing the movement this weekend and will perform the same mod to this movement. E

Let me know if you're successful, E, as it's been a bust on my end. I've spent the last week trying to contact DW for a refund, and he's gone completely silent to all of my emails.

I think I've been one of his most vocal defenders on these boards, but DW has really been trying my patience over the past few months.

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Let me know if you're successful, E, as it's been a bust on my end. I've spent the last week trying to contact DW for a refund, and he's gone completely silent to all of my emails.

I think I've been one of his most vocal defenders on these boards, but DW has really been trying my patience over the past few months.

He is not replying my emails either concerning the mystery movement(yes, I am feeling a bit adventurous)

The driving gears seem completely different than the other DW a7750 movements that I have as spare parts sources. I even tried to swap the top plate entirely, only to find that there minute counter driving gear is pressed against a peg built into the main plate and again, nothing to drive it. If anyone else found a work around for this let me know. If not, I will put it all back together and sell them.

E

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