Seiko 6139

[RyanGreerMcGilloway]

Hi all experts.

 

i have recently brought a seiko 6139 chronograph from Venezuela which wasn’t working at the time and I had tried to fix the balance but ruined instead. 
 

I have brought a donor movement to replace this whichh the balance on this movement was working fine and spining  freely.

 

now I have reassembled all of the movement and Serviced it. All wheels are working perfectly, the pallet fork is working as it should. However, when I then put the new balance on the movement. It doesn’t spin freely and doesn’t work as should. I have tried the pallet fork in both positions and the balance does nothing but struggle to spin freely. Can anyone advise. 

[Melt]

Without the pallet fork does the train run freely when you wind the mainspring?

As you have a spare movement......

Have you swapped the pallet fork and or its bridge? Try swapping the escape wheel as well.

Finally have you oiled the diashock jewel in the balance?

Edited December 16, 2020 by Melt

[Nucejoe]

Check endshake on staff, if no endshake, both endstones might be pushing on pivots.

You can also loosen the stud screw 2 to 3 turns to release pressure on end stones.

if this did no good and you haven't check both the upper and lower jewel assemblies, you might have broken or very dirty jewel.

Third possibility is if something is rubbing, like hairspring runbbing on balance spokes or the cock, or pivot shoulder rubbing on jewel housing.

Good luck.

[Nucejoe]

9 hours ago, Nucejoe said:

Check endshake on staff, if no endshake, both endstones might be pushing on pivots.

You can also loosen the stud screw 2 to 3 turns to release pressure on end stones.

if this did no good and you haven't check both the upper and lower jewel assemblies, you might have broken or very dirty jewel.

Third possibility is if something is rubbing, like hairspring runbbing on balance spokes or the cock, or pivot shoulder rubbing on jewel housing.

Good luck.

Correction: You can also loosen" THE COCK SCREW"   2 to 3  turns to release presuure on endstones. 

I had written "stud " instead of screw. 

Loosen the screw to a point that staff shows a bit of emdshake, nominally .02mm endshake is ideal.

If the issue turned out to be "no end shake" you might want to shim up balance cock or bridge to create some endshake.

 

[RyanGreerMcGilloway]

How can I unscrew this balance staff because I think that might be the issue. Just having the staff pressed down with nor movement in it

[watchweasol]

What Joe refers to is the balance cock( the part which holds the balance wheel), Just back off the screw a half turn and see if the balance starts up, Check the end shake of the balance wheel if it now runs shim the balance cock with a little aluminium foil (temporary )and re tighten the screw if it still runs  then the problem is lack of end shake. If that is the case the balance jewels/settings may need adjusting.

[JohnR725]

17 hours ago, RyanGreerMcGilloway said:

I have brought a donor movement to replace this whichh the balance on this movement was working fine and spining  freely.

 

now I have reassembled all of the movement and Serviced it. All wheels are working perfectly, the pallet fork is working as it should. However, when I then put the new balance on the movement. It doesn’t spin freely and doesn’t work as should. I have tried the pallet fork in both positions and the balance does nothing but struggle to spin freely. Can anyone advise. 

I'm having a minor confusion here? So the first part you have a donor movement balances in everything works fine?

Then his service the watch but you have a reference to putting a new balance wheel in? So is this the balance wheel that up above was working fine or is this an entirely new balance wheel?

15 hours ago, Nucejoe said:

Check endshake on staff, if no endshake, both endstones might be pushing on pivots.

If I make the assumption that the donor movement balance wheel was working fine and that's still the same balance wheel after servicing it's not working fine then there's probably still nothing wrong with that balance wheel. But if you find when you're tightening the bridge screw for the balance wheel balance stops spinning it may be the balance  jewels if you took them out. It's usually not clear in the servicing guide but the end  stones have a curved surface and a flat surface. In some watches there actually a different thickness whether there on the one side or the other. you want to make sure that the curved surfaces out because otherwise that is a place you'd lose your end shake.

I am attaching a picture as that's always helpful hopefully.

[Watchfixr]

According to my Seiko parts interchangeability guide, the upper and lower cap and hole jewels are identical. Swapping them should not be an issue. There have been a lot of good suggestions made here. What does the balance do with the pallet fork removed? does it have good motion then? How about with the hairspring removed? It should spin freely. just some things to check. According to my Seiko reference on the 6139A, the chronograph adjustments can be a real beast to get right. make sure the time train is in good condition before starting on that.

[Nucejoe]

On 12/17/2020 at 1:08 PM, RyanGreerMcGilloway said:

How can I unscrew this balance staff because I think that might be the issue. Just having the staff pressed down with nor movement in it

Sorry, I meant loosening cock screw, miswrote the word stud instead.

Considering that balance spun freely on other movement, staff pivots are alrignt.

Moving jewels as weasol says is actually prefered to shimming, seiko jewels are easy to move, I can move em without jewelling tool.   

 

[RyanGreerMcGilloway]

Hi all I think I have finally discovered the error with the balance. It wasn’t the balance itself. It seemed to have been the pallet fork. Now, I’ve purchased a NOS pallet fork for the same movement and I’ve come Across another hurdle, whenever I Place the fork in its jewel and the bridge on top and screw into place. The forks snaps as it should a few times and then seems to jam and I can’t figure out why. This is the course to the balance not turning. The wheels work perfectly when the forks not in place as well

[Nucejoe]

Do you have enough end shake on fork arbour?   if yes; 

I would keep nudging the fork to snap until it jams there ink mark the escape teeth and the pallet in contact with the teeth.  If it kept jamming on the same tooth, that is where the fault is, most likely a defective tooth, perhaps dirty.

One you have ink marked the tooth, you might put the oscilator-cock assembly back on, shake to run the oscilator at low wind, see where it stops.

Good luck and happy Christmas.