Repairing a new Shanghai A581 remake watch...

Discussion in 'Wrist Watches' started by pmwas, Jun 16, 2019.

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  1. pmwas

    pmwas Registered User

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    #1 pmwas, Jun 16, 2019
    Last edited: Jun 16, 2019
    Hi!

    This is a post about me repairing a very cheap chinese watch I bought in 2017.
    It's a cheap Shanghai A581 remake, for everyday use. I like the vintage looks of it and I think it's a great looking watch, and also… it's very inexpensive.

    DSC00082.JPG

    That's my watch here, and here's the review I've wrote back then on WatchUSeek.:

    Shanghai A581 - a Chinese reissue

    Like I've wrote on Friday, the watch broke, so I got a chance to open it and see what's inside:

    DSC00334.JPG

    The poorly finished movement (not the worst I've seen, but the finish quality is poor) is the standard Chinese caliber made since 1970s.

    As you can see, the problem is with the ratchet wheel that disengaged the crown wheel:

    DSC00332.JPG

    This should not be possible at all, so either the screw was loose or maybe it's because the ratchet wheel has too much play on the barrel arbor.
    Examining it, yes it does have some play and also it's somewhat thinner than the earlier wheels I have in stock.
    I was even thinking I could replace the ratchet wheel, but first, I just wanted to make sure it's needed to replace a part, so I reattached the wheel and that's where the real problem started.
    Usually when I screw down the ratchet wheel, I screw it down till it starts turning, then I wind up the watch and tighten the screw when it's fully wound (so that the ratchet wheel won't turn easily anymore.

    OK, OK, because of the ratchet wheel problem I did use a tad more force than usual, and so - maybe I did put a tad too much force, but I'd expect the (very thin) screw thread to give in first in such case, while no...
    The tightening of the screw caused two issues - firstly, I cracked the chrome coating of the screw (yes, the Chinese make chrome plated steel screws, believe it or not...).
    That's a cosmetic issue, painful, but quite meaningless. The other thing was that oddly, the ratchet wheel advanced a few clicks ahead with an ominous sound coming from inside of the movement.
    I was sure I damaged (stretched?) the mainspring, and the fact that the watch would not work anymore kind of confirmed it.

    So I took the barrel apart, removed the mainspring (which looked good), relubricated the (DRY as Sahara sands!) barrel and used a different mainspring to make sure. However, the watch still would not run a bit.
    So I put the original mainspring back in the barrel, and disassembled the whole movement to see what's wrong.

    I just could not believe my eyes:

    DSC00336.JPG

    The center wheel lost a great deal of teeth (wheel on the left, on it's right, it's not a light glare, there are not teeth there ;) )!

    [EDIT] better pic for you:

    DSC00352.JPG

    I broke the center wheel with my screwdriver, by tightening the ratchet wheel screw.
    It's just hard to believe, I'd not even think it's possible.

    OK, maybe in a very, very small ladies' watch, but then again - I'd still expect the screw thread to beak first, not the center wheel!
    I had an old Chinese movement in my drawer, so I took a replacement wheel from there.
    It's in near perfect condition, so I could use it to repair my watch.
    I assembled the watch, but it would not run with the new wheel.
    WHY:???:

    It seemed like now the center wheel would rub against the pallet fork, locking the movement.
    I examined the wheel to check if it's all nicely flat (which it was), compared the sideshake and the endshake with the original wheel, compared the wheels - without any precision measurements, they looked the same, so probably there was just a micrometric difference between the two.

    Finally I took the donor movement's pallet fork to compare, and again - it was all the same (but then again - I used just a magnifying glass to tell).
    Actually I even intended to try the other fork for my watch, but the new one was al nice and shiny, while the old one... you know :)
    So I assembled just the center wheel and the fork and I found the problem.
    On the new fork, there was a thick, somewhat excessive, blob of shellac on the exit pallet.
    I used a heated screwdriver to flatten the blob and reassembled the movement again (photo showing the blob before I flattened it):

    DSC00339.JPG

    The movement is of very simple design, actually very similar to most of the movements of this type (direct drive sweep second).
    There is a separate bridge for the center wheel, then there are the 3rd gear and the 4th that's co-axial with the center, and then the escape wheel.

    DSC00345.JPG

    After reassembling (damn it, another screwdriver slip, but the notch in this screw is very shallow), the watch started running and it still after over an hour, so I think it should be fine now.
    Conclusions?
    Pay attention to details and don't tighten screws too much.
    I keep saying it and yet I sometimes tighten them myself :)
    It's funny, the 'natural' urge to try to tighten a screw in such cases. It won't help, but one still gives it a try ;) .

    And just a slight Off-Top to end my post - here's my new toy :) :

    DSC00351.JPG

    I have not had one for like 15 years now.
    My dad took all the vinyl plates with him, so I now have to get my own collection, but it's soo good to hear the pure, analog sound again ;)
     
  2. Peter John

    Peter John Registered User
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    I’m thinking you did not do that damage when you tightened the arbor screw. The damage was done when the ratchet wheel lifted and disengaged from the click, thereby suddenly releasing all the power of the mspg. To properly tighten the barrel arbor screw I block the click with a screwdriver so the wheel cannot turn. Then if you choose you can tighten enough to snap off the head of the screw. Really tho, you don’t want to tighten that much but the way you did it you could break the mpg. Peter
     
  3. pmwas

    pmwas Registered User

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    I'm nit going to try again, but the wheel is thin and I'm quite convinced I really did it with my screwdriver. Maybe one day I'll find a dead 'Chinese standard' and check ;)
     
  4. RL

    RL Registered User
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    A "Denon" turn table. A very nice one.
    That brand was quite popular during the Golden era of stereo systems.
     
  5. pmwas

    pmwas Registered User

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    Yes, a very nice turntable indeed.
    Good quality and fully automatic (which you might like or not).
    Of course, the cartridge can be replaced with a better one.
    The only thing is that it's not idiotproof, and when I once pressed start again instead of stop, it sent the arm far to the label (not lifting it!!!), and since the buttons are next to each other - beware!!!

    But enough with the off-top.

    Back to my Shanghai - after the repairs it started loosing over a minute a day, and I wonder if I accidentally moved the regulator or if my work really did alter the rate so badly:???:
    I think it might be a good idea to fully service it now...
     
  6. pmwas

    pmwas Registered User

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    #6 pmwas, Dec 23, 2019
    Last edited: Dec 23, 2019
    Today I finally tried to do something with my locking click...



    As you see - the click locks and the watch won’t wind. I don’t know why, it looks fine.
    The watch works fine and suddenly it locks and you have to unlock it manually. Then it works for some time and locks again. It’s the third time now.

    I replaced it with another click and we’ll see.

    I have to admit, I thought cheap Russian movements were bad, but they are great compared to this crap...

    Surely the Chinese can give the word ‚crap’ a whole new meaning :)

    Funny thing - I do like this watch, that’s why I care. I should have thrown that away a long time ago, but I like it :)
     
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  7. pmwas

    pmwas Registered User

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    It worked for a day.

    2C50BED1-E81E-40CE-B333-558D36B563FE.jpeg

    The winding disintegrated again and mainspring broke.
    I think I’ve had enough of this watch now :)
     
  8. pmwas

    pmwas Registered User

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    With the remarkable set of tools (I’m not at home)...

    4B6704E2-F02E-4E19-99D4-B59E7EDB5D67.jpeg

    ...I made my way to the mainspring. It’s not broken, only bent due to the winding gear malfunction. I put that back together and it works, but with this winding mechanism, it won’t work any long...
     
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  9. pmwas

    pmwas Registered User

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    Ok - I got back home and disassmebled the watch again. To fix the winding issues for good (I hope)...

    22DDC584-4855-4765-BF0C-DF2A4751B70F.jpeg

    The good thing about these (and similar) movements is that you don’t have to even remove it from the case.

    It is easier to do it in setting position.

    I noticed that the clutch gear has a damaged tooth, likely responsible for the winding problems (poorly engaging the winding pinion).

    74863911-5907-447A-B72E-16D861C4AC7F.jpeg

    I left the stem in płace in the parts’ mvt - I’m rarely so wise, so that’s lucky!

    DE224826-2656-4493-A7F4-91DC594F58B7.jpeg

    Initial winding went smoothly, so I’m hoping for the best. Maybe if the winding stops disengaging all the time, the ratchet wheel won’t unscrew itself any more. If not - I’ll have to look for a new barrel arbor...
     
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  10. pmwas

    pmwas Registered User

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    Ok, so far so good - winds up all right. The winding is very stiff, but I heard that's typical for this caliber - stiff winding due to the gear ratios.
    I hope this ends the trouble with this watch, but... so I have already hoped before :)
     
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  11. pmwas

    pmwas Registered User

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    Finally I got to the reason the click keeps locking (locked again, yes). It is not the click, it is the winding gear.

    5EB4E888-4625-4AA4-A813-8039D2C84A5C.jpeg

    Not very clear here, the gear has a short tooth. This particular tooth fails to give the click the initial push (does not reach it) and so the other teeth won’t engage the click. That’s why it locks randomly and rarely - the winding has to end with this particular tooth being the one initiating the click’s action.

    I have a replacement gear, but of different finish and thicker. For now it will have to do...
    Hey, I’m still thinking of throwing this thing to the trash bin, where it belongs ;)
     
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