# What?s wrong with my chronograph?



## lysanderxiii (Oct 4, 2006)

*What's wrong with my chronograph?*

This pops up now and again - your new chronograph is not doing what you expect it to do, and you want to know why....

The purpose of this article is to explain what happens in the chronograph section that affects the overall watch operation.

First let's look at a simple castle-wheel chronograph, the ST1901. The design of these is pretty much the same as all castle-wheel chronographs, the parts are different shapes and the finish differs, but for the most part the operation of each part is the same.










Normal operation:

Depressing the start button advances the castle wheel clockwise by one index position, this is accomplished by the long sweeping lever stretching from 4 to 11.30 in the above picture. This allows the coupling clutch mount nose to drop in between the castellations the coupling clutch engages the second wheel, other castellations cam the reset hammers off the reset hearts to the cocked position where they are latched and lift the brake lever. After the second wheel rotates one revolution a tooth under the gear engages the slider gear and advances it one tooth position. The minute recording jumper prevents the minute recorder from advancing more than one position.

When the start button is pressed again, the castle wheel advances another position and the castellation cams the coupling clutch mount nose out and disengages the gears. It also allows the brake lever to drop in between two castellations and stops and holds the second wheel so motion of the watch will not alter the indicated second position.

The ST19 is a drop hammer design depressing the reset button releases the hammer, which under influence from the hammer spring falls on the reset hearts. It also lifts the sliding gear out of the way of the single tooth on the second wheel and lifts the brake.

(Some older chronographs have pusher operated hammers that when the pusher is depressed, the pusher lever acts directly on the hammer, against the hammer spring and the reset hearts. The hammer still performs the above functions, releasing the button allows the hammer to return to the cocked position. In these designs, a half hearted push on the reset button with not reset the hands to zero, which is why they were dropped in favor of the drop hammer design.)

Now, how to adjust the chronograph, it is best to start at the coupling clutch cam and work clock-wise:

The *coupling clutch cam* adjusts the depth of engagement of the coupling clutch gear and the upper 4th wheel. Too much engagement will put excessive drag on the movement and possibly stop it. If the engagement is too loose there will be excessive backlash between the gears and the second hand will stutter. If this cam is rotated 180 degrees out, it will move the coupling clutch nose too far away from the castle wheel and the chronograph will not start even after the start button is pressed.

The *chronograph depth cam* adjusts the depth of engagement between the coupling cam and the second wheel. Again, too much engagement will put excessive drag on the movement and possibly stop it. Too little will result in stutter or second hand jump at chronograph start. The engagement should be 2/3 the tooth height.

The *sliding gear depth cam* adjusts the depth of engagement of the sliding gear and the single tooth of the second wheel. Too little engagement will result the single tooth missing the gear altogether or not tripping the minute counter. Too much will result in the minute counter jumping two minutes or bouncing after indexing.

*Minute recording jumper adjustment*, when the minute counter is reset, the jumper detent should be resting evenly on two teeth. Loosen the screw and use the cam to adjust the up and down position of the jumper detent. If it is not adjusted properly, the minute counter will reset to one position, then move to another position when the start button is depressed.

Adjusting a lever operated chronograph is much th same, in fact the only difference between a cam operated chronograph and a castel wheel chronograph is that a two position cam replaces a continuously rotating castle wheel. The start lever moves the operating cam to one position generally the hammer cocked position, and the reset lever moves the operating cam to the hammer down position.










The above is a Poljot 3133, but it is typical of most lever-operated chronographs, although the cams are in different places.

These have one additional cam, the chronograph disengagement cam which, when the hammer falls, allows the coupling clutch to be pushed out of engagement with the second wheel. If this cam is incorrectly set, the coupling clutch will be either too close and not disengage, or too far. If too far the coupling clutch will drop to far and cause second hand jump on engagement.

So, troubleshooting:

1) watch doesn't run -
- Something wrong in the watch section.
- coupling clutch engaged too deep in upper 4th wheel.

2) watch stops when chronograph is engaged -
- chronograph depth cam set too deep.
- something jamming second wheel.
- reset lever spring broken and hammer is not latched in cocked position.

3) chronograph doesn't start when start button pushed -
- start lever broken.
- start lever spring broken and castle wheel not rotating.
- chronograph depth cam not set deeply enough.

4) minute counter doesn't index-
- slider gear depth cam set too far out.
- second wheel single tooth damaged or missing.

5) minute counter jumps more than one position at a time -
- slider gear depth cam set too far in.

6) minute counter reset to one position, but moves when chronograph started -
- minute recording jumper incorrectly set.

7) chronograph second or minute recorder resets erratically or not at all.
- reset button not being pushed with enough authority (fly back or non-drop hammer designs only.)
- reset lever damaged.
- hammers not in full contact with reset hearts.
- second hand or minute counter hand loose.
- weak hammer spring.

8) watch stops when reset button pushed -
- brake not disengaging.
- slider gear not disengaging.
- coupling clutch mount nose deformed and coupling clutch not disengaging.

I don't think this is all the possible failures, but it is the most common ones.


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## Chascomm (Feb 13, 2006)

*Re: What's wrong with my chronograph?*

Thank you for that comprehensive introduction to the magic that lies beneath the surface of a chronograph. I am sure that many members here will find this post very practically helpful.


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## TO_ARCH (Dec 29, 2009)

*Re: What's wrong with my chronograph?*

Thank you :-! very informative thread!


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## Pawl_Buster (Mar 12, 2007)

*Re: What's wrong with my chronograph?*

Thank you for yet another excellent article :-!

But I'm still not going to tackle working on a chrono :-d


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## skywatch (Aug 3, 2010)

*Re: What's wrong with my chronograph?*

I love your technical postings, Lysander. Thank you for this effort - it really helps to educate us common folk.


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## RON in PA (Sep 11, 2007)

*Re: What's wrong with my chronograph?*

Thanks!


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## Reno (Sep 23, 2008)

*Re: What's wrong with my chronograph?*

Another thanks here :-!


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## Oldheritage (Jan 3, 2009)

*Re: What's wrong with my chronograph?*

+1, your work is really appreciated :-!


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## gigfy (Apr 13, 2007)

*Re: What's wrong with my chronograph?*

Thank you very much for taking the time to put together this information. This thread has been added to the reference section!

cheers,
gigfy


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## AlbertaTime (Dec 27, 2008)

*Re: What's wrong with my chronograph?*

I'm really grateful for this, Lysanderiii...and I'm sure I'll appreciate it more as it starts to sink into this easily overwhelmed brain of mine ;-)


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## tecrose (Dec 23, 2010)

*Re: What's wrong with my chronograph?*

Really informative post!

My M199S developed the minute counter problem (problem number 6). It resets to 29.5 and advances to 30 (0) when started, then the operation is normal until I stop and reset again.

It is quite frustrating considering that it just went back to the factory for the chrono second hand not resetting to 0 problem. It took 76 days to get the problem corrected, and 5 days later the minute counter is acting up. I really hope it doesn't require another trip back to the factory. But it seems like there's nothing I can do. Any suggestions?


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## jason_recliner (Feb 2, 2009)

*Re: What's wrong with my chronograph?*

Great post Lysander!


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## Lemon328i (Apr 16, 2009)

*Re: What's wrong with my chronograph?*

This is a great thread! I have an ST1901 that exhibits the weak hammer spring issue. I haven't been able to source a replacement part though. Is slightly bending the part to increase tension a workable solution?


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## Will_f (Jul 4, 2011)

*Re: What's wrong with my chronograph?*



Lemon328i said:


> This is a great thread! I have an ST1901 that exhibits the weak hammer spring issue. I haven't been able to source a replacement part though. Is slightly bending the part to increase tension a workable solution?


I suspect Seagull has a problem with QC on their springs. My ST1901 broke the click spring that keeps the watch mainspring from unwinding. Given the watch has probably been wound less than 200 times, the spring must have been pretty marginal.

Sent from my SM-T520 using Tapatalk


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## Lemon328i (Apr 16, 2009)

*Re: What's wrong with my chronograph?*

It might be their metallurgy. Still, if the click spring and hammer springs are weak points, I'm surprised no one has taken measurements and made upgrade parts. The hammer spring is just a curved lever. If made from spring steel or designed a bit thicker, it should push the hammer reliably every time.


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## Lemon328i (Apr 16, 2009)

*Re: What's wrong with my chronograph?*

I decided to take a chance and see if slightly bending the hammer spring to increase tension would work to make reset more reliable.

Taking it out of the movement was pretty straightforward if you have the right tools. The hammer spring (a sort of "C" shaped lever) is held in place with one screw and a protruding pin underneath that fits into a corresponding hole. The bottom end of the spring engages a screw in the hammer that is upside down i.e. the screw head is not visible. When the chronograph is running, the hammer is cocked back and tension is put on the hammer spring. When you stop the chronograph & press the reset button, the hammer is tripped to fall on the minute and second "hearts" to reset the hands back to zero.

I managed to very slightly bend the
hammer spring which added just enough extra potential energy for the hammer to reliably fall every time. We'll see how long this holds or if the hammer spring will eventually take a "set" to a weakened state again. It might just be that the factory bending was just slightly off.


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## mike4761 (Jun 29, 2015)

*Re: What's wrong with my chronograph?*

Lysander never disappoints. Great job! The Poljot looks like it was made in a truck factory by the machining marks and file like finish.


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## Solotov (Nov 27, 2017)

Ressurecting a dead thread here.

So I've got a Poljot 3133 that hit the deck a bit ago. Maybe 2 feet onto thin carpet, not good. So the regulator got all moved outta wack and I adjusted that back to normal and the watch is running reasonably accurate, although i havent got the timeographer out yet. The chronograph functions all work fine when the watch is wound up reasonably well too. 

But the damn thing is rattling! It sounds like a cheap automatic with a noisy [email protected] Anyone know what this could be? It's not really effecting functionality of the watch but now it just feels cheap. I don't have any other 3133 movements, so I don't know if that's how they normally feel/sound. (got a 31659 in the mail though, i guess that will be a good thing to compare it to) Anyone know what could be rattling? I can post pictures when i get home here of the movement.


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## Monkey_like_watch (Mar 1, 2017)

Solotov said:


> Anyone know what this could be? It's not really effecting functionality of the watch but now it just feels cheap. I don't have any other 3133 movements, so I don't know if that's how they normally feel/sound. (got a 31659 in the mail though, i guess that will be a good thing to compare it to) Anyone know what could be rattling? I can post pictures when i get home here of the movement.


You might want to post your question in the forum f6 "Watchmaking" of WUS, here is the link:
https://www.watchuseek.com/f6/


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## Solotov (Nov 27, 2017)

Monkey_like_watch said:


> You might want to post your question in the forum f6 "Watchmaking" of WUS, here is the link:
> https://www.watchuseek.com/f6/


I did end up crossposting this, actually thought that was where i was TBH. Didn't realize when i bookmarked this thread that it was outta my f10 home:roll:


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## Chascomm (Feb 13, 2006)

Would this watch happen to have the classic case with the inner bezel and second crown at 9 o'clock? If so, then there is a good chance that it is not a movement issue at all but just the inner bezel rattling around, which is fairly normal.


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## Solotov (Nov 27, 2017)

Chascomm said:


> Would this watch happen to have the classic case with the inner bezel and second crown at 9 o'clock? If so, then there is a good chance that it is not a movement issue at all but just the inner bezel rattling around, which is fairly normal.


It is indeed that case. I opened up the back and checked for loose components and nothing seemed out of place, so i will assume it is as you say. Just the inner bezel making some noise. 
Small price to pay for such a watch


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## Solotov (Nov 27, 2017)

Crossposting again, wouldn't want to leave a wealth of inormation untapped

I've got a followup question about a new 3133 i received. If I put it on my timeographer it's running fantastic, maybe +5 sec per day in every orientation i've tested. But for some reason it will lose massive time overnight maybe 15 minutes or so. Both on my wrist if i sleep with it and in the watch box. I'm not sure what could be causing this to happen.


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## Solotov (Nov 27, 2017)

Double post*


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## Chascomm (Feb 13, 2006)

Solotov said:


> Crossposting again, wouldn't want to leave a wealth of inormation untapped
> 
> I've got a followup question about a new 3133 i received. If I put it on my timeographer it's running fantastic, maybe +5 sec per day in every orientation i've tested. But for some reason it will lose massive time overnight maybe 15 minutes or so. Both on my wrist if i sleep with it and in the watch box. I'm not sure what could be causing this to happen.


Well it's not really a question of the chronograph function, but there is only one thing that happens overnight in a 3133 that doesn't happen in the day; the date changes. I'm guessing that somehow the calendar mechanism is dragging on the movement.


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## Mrs Wiggles (Nov 7, 2018)

*Re: What's wrong with my chronograph?*



Chascomm said:


> Thank you for that comprehensive introduction to the magic that lies beneath the surface of a chronograph. I am sure that many members here will find this post very practically helpful.


Not me, I am completely lost


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## AccoBo (Dec 19, 2020)

Hi I bought an ST1903, dial and hands. The movement seems to be ok and hands have been carefully fixed on the movement. It runs ok, even the chrono, but when I reset the chrono, the seconds hand doesn't go back to 12, it goes back at about 12 plus 2 seconds. Again, if I let the chrono go and then stop and reset it, it goes back at 12 plus 2 plus 2 seconds. So, any time I reset the chrono it goes ahed 2 seconds. I read the nice instructions at the beginning of this post, but I don't see this issue. Any idea? Thank you.


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## LCheapo (Jul 14, 2010)

It sounds like the chronograph seconds hand is not as securely attached as you believe.


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## AccoBo (Dec 19, 2020)

LCheapo said:


> It sounds like the chronograph seconds hand is not as securely attached as you believe.


Ok, I'll try to remove the seconds hand and then attach it again. But I am still convinced it was...


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## miroman (Oct 29, 2010)

Maybe the seconds hand itself isn't accurately assembled - the tube is not pressed well in the hole of the body of the hand. Sometimes it happens after a lot of attaching and improper detaching. This can cause the body of the hand to rotate relative to the tube.
You can test this - take the tube with tweezers and try to rotate the body of the hand - very carefully of course . If you succeed to rotate it, maybe the tube has to be pressed additionally to fix to the body.

Regards, Miro.


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