Inside an ST16 (lot's of images)

[rolexio]

It is an Alpha watch with an ST16 movement. So this means I should contact Alpha and request for a replacement?

You mention 2 reasons for the hand jumping experience

1) Because the the gear train is stalled upstream of the balance, the balance will continue to swing and possibly unlock one of the pallet jewels but not swing far enough to lock the other one. When the hack lever is released, tension is returned the the gear train and the escape wheel will start to turn, the pallet may not be able to engage the first tooth on the escape wheel and allow the movement to jump ahead slightly.

2) The arresting of the third wheel with the hack lever causes the second hand pinion gear to move out of contact with the third wheel, releasing the third wheel allows it to move forward and hit the second hand pinion with enough force to move it out of contact again. This is basically the same mechanism that causes the second hand stutter in the Miyota 8215.

Does this happen only when movement is defective or can it happen more times? In mine it happens like always so I will have to contact Alpha for a replacement. Think won't be getting it back for Christmas .

[W123]

I wouldn't bother. They will send you a replacement watch that will do the same thing.

Just accept the watch as it is, a 50 dollar mechanical watch and enjoy it.

[rolexio]

So that means ST16 movement is design flawed? This is something I still didn't get a clear answer.

Does the behaviour I have experienced

* 1 When setting time, movement hacks as expected but as soon as I set it seconds hand jumps like 4 seconds
* 2 If I shake it, seconds hand just stops for a brief of time. After it starts working again it starts gaining time. In about 2 hours it is like 7 seconds faster (so in a day over a minute)

occur in all ST16 movements (design flaw) or I just got unlucky here? I do not blame Alpha but Seagull for such a bad movement .

[lysanderxiii]

So that means ST16 movement is design flawed? This is something I still didn't get a clear answer.

Does the behaviour I have experienced

* 1 When setting time, movement hacks as expected but as soon as I set it seconds hand jumps like 4 seconds
* 2 If I shake it, seconds hand just stops for a brief of time. After it starts working again it starts gaining time. In about 2 hours it is like 7 seconds faster (so in a day over a minute)

occur in all ST16 movements (design flaw) or I just got unlucky here? I do not blame Alpha but Seagull for such a bad movement .

The problems you have sound QA related. No watch should gain that much time, no matter how inexpensive. (Anything above 60 seconds/day probably should be returned.) Return the watch. Alphas customer service is good from what I hear, never had to us it myself though.

The hacking quirk does not show up in all ST16s, the one dissected above did not show this and none of the others I have come across have done it to the degree that I would notice. However, the design does allow this possibility, so when you get the new/repaired watch, even though it should keep time correctly, it still may jump a little on hacking.

Good luck.

[Reno]

Thanks lysanderxiii, it's always interesting to have a view inside the machine
Thanks a lot !

[nhoJ]

Are the date wheels plastic?

[lysanderxiii]

Are the date wheels plastic?

No.

Brass, just like in any decent movement.

[jlaranjeiro]

Hi every one!

I am new in this things but recently and after seeing this site and search for affordable watches i buy a Sea-Gull M177s (ST16) and a M188s (ST2501). Until now I'm very happy whit both watches, because ST16 just give me +17s a day and ST2501 +7s day, nothing to compare whit my Hamilton (+5s/+10s a month, is hard to believe but is true...).

Just a note, i bought them (ST16 and ST2501) from Kevin of the Usseagull.com, and it was a really good experience, he is a 5* seller and it become more cheaper buying in US them buying in Europe, since I'm from Portugal.

Congratulations for the thread, it really help me when I was looking for some watches.

[M4tt]

I think that in discussions like this it is worth remembering that there are two ways of looking at precision and regulation.

First, there is deviation from a known timebase. This is simply how much the watch gains or loses in a single measurement of a set period of time against a known timebase..

Second there is stability. This is how much the deviation varies from one measurement to another.

Stability, not eliminating deviation, is the holy grail of horology. If a watch is stable at +17 then a little regulation will allow it to be equally stable at 0. However a watch that varies by say +4 to -4 over a series of 24 hour periods is already as accurate as it is going to be without surgery.

My experience with Chinese movements is that they are remarkably stable at the price and thus, while usually poorly regulated, are a doddle to regulate to remarkable accuracy by hand.

I'm also curious as to which Hamilton movement is achieving a stability of deviation that is half that of an average quartz.

[ckhouse80]

Greate work.

I have quite a few threads on the ST-16, but I can't recall one that goes into the insides of one. So here in a few pictures is the disassembly of an ST-16...

Here is the basic side of the ST-19 we all see: (pardon the finger prints and dirt, this is my spare/parts movement, so it's not the cleanest thing.)



Here we have removed the auto-wind bridge, we can now see the second hand pinion friction spring, the auto winding "magic fingers" have been moved to one side to afford a better view of the spring.



Here is the underside of the auto-wind bridge showing the magic fingers and how they work.



Here we have removed the 3/4 bridge exposing the inner workings of the movement. Items to note are the hack lever (the "V" shaped piece near the stem), which acts on the third wheel rather than the balance in most movements. (Sometimes hacking these movement shows particularities not seen in other designs, this is the reason.) Also, we now can see the third wheel engages both the fourth wheel and the second hand pinion.



The third, fourth and escape wheels have been removed along with the second wheel bridge and balance assembly. Items to note are the adjustable banking on the pallet cock.



Here is the dial side, with the date wheel and the cover plate removed so you can see the quick change arm and the all the dial side wheels.



Parts: (l to r, t to b) Rotor; Rotor Screw; Transmission Wheel; Pawl Lever, with jewel; Auto Bridge Screws (2x); Auto Bridge



Bridge Screws (3x); Second Hand Pinion Friction Spring; Second Hand Pinion Friction Spring Screw; Main Bridge with the Floating Winding Gear still attached; Fixed Winding Gear.



Click; Barrel (Mainspring installed); Ratchet Wheel; Pallet Cock Screws; Pallet Cock; Pallet Fork.



Escape Wheel; Second Hand Pinion; Hack Lever; Second Wheel Bridge Screws (2x); Balance Cock Screw; Fourth Wheel; Third Wheel; Second Wheel; Second Wheel Bridge; Balance Cock, with Balance Assembly; Cannon Pinion.


Date Dial Guard Screws (3x); Date Dial Guard; Intermediate Date Wheel; Date Dial; Date Jumper Spring; Date Jumper; Hour Wheel; Date Corrector; Date Driving Wheel; Intermediate Setting Wheel; Minute Wheel.


Mainplate (Stem; Clutch Wheel; Setting Lever; Setting Lever Spring and Yoke still installed)



These movements are, design-wise superior to many older Swiss movement such as the AS1900 series, at least in my opinion. They are simple and robust, even if there is not much decoration or artistic arrangement of the bridges as there are in the Swiss stuff.

And one last thing, although this and the Miyota 8215 share the same design for the second hand, you do not hear of "second hand stutter" on these as much as on the Miyota.