Any tips on how to do a basic diagnosis/repair on a halted mechanical movement?

[DoctoralHermit]

My ST19 moonhphase (manual wind, chronograph) just stopped today without warning. Before, it was keeping rather accurate time... I believe within 10 seconds per day.

Any tips on how to give it a basic look-over, and possibly an easy repair? I read that using a squeeze blower might dislodge any particles that may have lodged themselves in the movement. Is this advisable? Anything else I should try before I commit to a more major servicing or movement swap?

[jdm]

No problems with blowing air. Then about diagnosis, repairs or just servicing have a good read around this website or books.

[watchweasol]

Hi  I should have a good look at Mark. Our Administrators videos before you embark on your journey as to be  au fait with watch movements and their workings, as jdm said do a bit of good reading. 

[Nucejoe]

-Note the seconds hand position, shake the watch, see if it runs and for how long or if'it  doesn't.

-If doesn't want to run when shaken, see if the sweep second rocks back&forth.

-Try to give it a full wind, see if the barrel( wind) discharges power.

-Pull the crown out to set postion, shake the watch, see if you can push it to run by simultaneously advancing the time. If locked up, Do the same in opposit direction.anticlock, 

-If a calender complication, advance the time to about six Oclock, see if runs then.

-Shake the watch as you listen close, if you can here a noise you didn't use to before.( Sound of sudden power discharge)

 

The results help diagnosis and advice.

Good luck.

[Nucejoe]

1 minute ago, Nucejoe said:

-Note the seconds hand position, shake the watch, see if it runs and for how long or if'it  doesn't.

-If doesn't want to run when shaken, see if the sweep second rocks back&forth.

-Try to give it a full wind, see if the barrel( wind) discharges power.

-Pull the crown out to set postion, shake the watch, see if you can push it to run by simultaneously advancing the time. If locked up, Do the same in opposit direction.anticlock, 

-If a calender complication, advance the time to about six Oclock, see if runs then.

-Shake the watch as you listen close, if you can here a noise you didn't use to before.( Sound of sudden power discharge)

 

The results help diagnosis and advice.

Good luck.

Opps , disregard the last item. Since manual wind.

[jdm]

I wanted to add, on't discard the possibility it has just overbankend. Easy to check, nudge gently the balance wheel, it will turn one direction but not the other. If so, loosen cock screw, raise balance and rotate into the direction it wouldn't turn. It will start beating right away.

[DoctoralHermit]

Thank you so much for all your replies! Here's my report:

• The second hand doesn't budge when the watch is shaken
• It's a small-dial second hand. Doesn't seem to move or wiggle when I shake the watch.
• I've fully wound it, and it seems to have stayed wound for a few days.
• Shaking the watch with the crown out doesn't produce any different results.
• Setting the time forward or backward doesn't seem to produce any different results
• Setting the time to 6:00 doesn't get it going either

One thing I do notice: when I advance the time forward, the date subdial changes accordingly.

[DoctoralHermit]

21 hours ago, jdm said:

I wanted to add, on't discard the possibility it has just overbankend. Easy to check, nudge gently the balance wheel, it will turn one direction but not the other. If so, loosen cock screw, raise balance and rotate into the direction it wouldn't turn. It will start beating right away.

I will certainly try this when I open the watch in the next few days! Thank you!

[Nucejoe]

Faulty escapement mech, possible broken fork or escape wheel pivots or fork arbour jewels  misaligned pallet jewels,  Thence, subsequent overbanking.

Missing or broken impulse jewel.

 

 

 

[watchweasol]

Hi  Without opening the watch and making an  educated   diagnosis its all guess work, there so many causes that could stop a watch, the main protaganists have all been mentioned. So untill the watch is open and the movement laid bare. Then the work will begin. First check the freedom of the balance in as much it swings bothways If it swings one way then stops It probably as jdm said overbanked. The prospect of a broken impulse jewel or pallet/fork jewel is also possible.  It is also possible it could be a jammed train  (dirt in the watch)    we await your report.   cheers

[DoctoralHermit]

I just opened the watch! It seems the balance swings freely in both ways. I've attached a picture of the movement... not sure if that will tell us anything!

[Nucejoe]

 Turn the balance wheel, see if it engages and makes the fork and escape wheel budge. 

Gently feel all gears see if any pivots to them is broken.

Release barrel power through the click.

[Nucejoe]

Flip the watch over on top of a white sheet of paper, to retract possible loose pallets or screws.

Do we have the datasheet for the movement? Good to take pix at all stages of strip down anyway.

[DoctoralHermit]

1 hour ago, Nucejoe said:

Flip the watch over on top of a white sheet of paper, to retract possible loose pallets or screws.

Do we have the datasheet for the movement? Good to take pix at all stages of strip down anyway.

Silly question maybe, but would this cause the movement to fall out of the case?

[Nucejoe]

Stems and movement retainer ring keep the movement in,  two retainer clips seem to be missing, pic is a bit unclear . How about placing a cup over the movement.

[watchweasol]

Hi  Now the work begins, Firstly have a look under or near the balance for a logo and a caliber number armed with both of these items we may be able to track down a Tech sheet.  So the balance swings both ways freely ok ,  when the balance moves round in an arc does the pallet/fork move in sympathy with it,  tick- tock, if so look at the pallet/fork ends there should be two ruby jewels on each end of the pallet/fork arms. If they are there and move in and out of the escapement wheel when the balance is swung in an arc that's ok. Now we need ti dig a bit deeper. the movement has to come out of its case and dial and hands removed and the power taken off the train, in other words what you have wound up (tension) has to be removed.  The reason for this is that the balance has to be removed, the escapement pallet/fork has to be removed and the freedom of the power train checked. I think that's enough for now. Having done all these checks and verified either good or bad then we can proceed.   Cheers