Stumped

[MarkF]

After successfully servicing a couple of ST 36 movements (clean, oil, reassemble) I moved onto a Seiko NH38. Everything seemed to go fine until I attached the balance. I carefully oiled all the parts as per the tech sheets. The wheels of the power train spun freely prior to installing the pallet fork. One the fork was installed I was able to wind it and power was retained in the system. But when I installed the balance wheel the amplitude was visibly very small - the timegrapher could even measure it. 
 

I disassembled it and started over, paying close attention to make sure that none of the pivots appeared to be damaged. Same results. I then swapped the balance wheel assembly for a new one I had from an NH35 movement thinking that maybe the hairspring was damaged. At first it seemed to run okay, but within a couple of minutes the amplitude dropped to about 140 from 250 and soon was no longer measurable. 
 

I am clearly doing something wrong, but short of taking everything apart, recleaning it and reassembling from there I have no ideas.  Does anyone have any suggestions of where to look?  The movement is brand new.

 

On the Timegrapher I get dots all over the screen instead of any lines, no readings for amplitude or beat and ++++ for rate. 

Update - I just spent some time adjusting the regulator. I now am getting readings. Amplitude is an abysmal 140 degrees, beat error of 1.6 and a rate that jumps around between -28 and +20 witching one minute while the watch is stationary (dial side down). I assume the rate jumping has something to do with the low amplitude. 

[nevenbekriev]

See what happens if You remove the cannon pinion.

[MarkF]

20 minutes ago, nevenbekriev said:

See what happens if You remove the cannon pinion.

No change (though somehow I stupidly just lost the canon pinion!). Rate is -11, amp 140. 

[Nucejoe]

Did you test the fork for snapping from side to side when nudged? 

Some end shake is neccessary, on all arbours.

Edited March 13 by Nucejoe

[rossjackson01]

3 hours ago, MarkF said:

After successfully servicing a couple of ST 36 movements (clean, oil, reassemble) I moved onto a Seiko NH38. Everything seemed to go fine until I attached the balance. I carefully oiled all the parts as per the tech sheets. The wheels of the power train spun freely prior to installing the pallet fork. One the fork was installed I was able to wind it and power was retained in the system. But when I installed the balance wheel the amplitude was visibly very small - the timegrapher could even measure it. 
 

I disassembled it and started over, paying close attention to make sure that none of the pivots appeared to be damaged. Same results. I then swapped the balance wheel assembly for a new one I had from an NH35 movement thinking that maybe the hairspring was damaged. At first it seemed to run okay, but within a couple of minutes the amplitude dropped to about 140 from 250 and soon was no longer measurable. 
 

I am clearly doing something wrong, but short of taking everything apart, recleaning it and reassembling from there I have no ideas.  Does anyone have any suggestions of where to look?  The movement is brand new.

 

On the Timegrapher I get dots all over the screen instead of any lines, no readings for amplitude or beat and ++++ for rate. 

Update - I just spent some time adjusting the regulator. I now am getting readings. Amplitude is an abysmal 140 degrees, beat error of 1.6 and a rate that jumps around between -28 and +20 witching one minute while the watch is stationary (dial side down). I assume the rate jumping has something to do with the low amplitude. 

Yup. Been there. Still wearing that T shirt.

[MarkF]

29 minutes ago, Nucejoe said:

Did you test the fork for snapping from side to side when nudged? 

Some end shake is neccessary, on all arbours.

Yup. When I oiled the fork it seemed to snap back and forth as I would expect (given very limited experience) and the escape wheel advanced as expected. There was not very much end shake on any of the wheels. All seemed as expected.

I will double check my balance jewels to make sure they are not upside down, though I hate the idea of fighting with the diashock springs again  

 

[watchweasol]

Hi. If you have had the balance jewels apart check the cap jewel installation .  Flat portion down . As it sound # like everything* is ok untill you put the balance in. This is where to start, check the end shake first it should be minimal but there should be some.  I take it you checked the train freedom before installing the fork and checked the fork end shake

[MarkF]

8 minutes ago, watchweasol said:

Hi. If you have had the balance jewels apart check the cap jewel installation .  Flat portion down . As it sound # like everything* is ok untill you put the balance in. This is where to start, check the end shake first it should be minimal but there should be some.  I take it you checked the train freedom before installing the fork and checked the fork end shake

I did. Train spin freely. The fork seemed okay but given limited experience that is an assumption. 

[watchweasol]

Hi Mark did the fork snap back and forth between the banking pis with power on  as that is a good indication that everything is ok in the power train. In your case when the balance is fitted the trouble starts,  yes,   Check points are is the spring flat, are the. Coils concentric, it’s not rubbing on the balance cock.  The balance staff is ok. No bent pivots,  One other point is to take out the fork and refit the balance and with your puffer blow the balance into action, does it rotate free and continue for about 30 secs

[MarkF]

13 hours ago, watchweasol said:

Hi Mark did the fork snap back and forth between the banking pis with power on  as that is a good indication that everything is ok in the power train. In your case when the balance is fitted the trouble starts,  yes,   Check points are is the spring flat, are the. Coils concentric, it’s not rubbing on the balance cock.  The balance staff is ok. No bent pivots,  One other point is to take out the fork and refit the balance and with your puffer blow the balance into action, does it rotate free and continue for about 30 secs

Yes. The fork snaps back. The spring looks flat to me and the coils appear concentric and evenly spaced. I followed your advice and installed the balance with the palette fork out. When I blew air on it it spun but stopped fairly quickly - so the issue is with the balance. I noticed it seems to wobble ever so slightly while spinning. Is that an issue with the pivots?  Not sure where to look next. 

[Nucejoe]

6 hours ago, MarkF said:

 When I blew air on it it spun but stopped fairly quickly - so the issue is with the balance. I noticed it seems to wobble ever so slightly while spinning. Is that an issue with the pivots?  Not sure where to look next. 

A test to check for bent pivot, when you don't have  dedicated tools .

Remove a cap stone, lock shock spring on chaton,  spin the balance, observe the pivot.

Replace the cap stone , remove other side's cap stone , to check the other pivot.

This test is as accurate as the observer. 

 

 

 

Edited March 15 by Nucejoe

[watchweasol]

Hi Mark   So the balance spins but stops quickly,  that’s indicative of pivot problems and jewels.  Next stage is to re move the balance and detach from the cock and make a close inspection of thr jewel seating and jewels. It is possible one is not fitting right.  When you removed them did you put the right setting in the right place ie. Top to top etc . Whilst the balance is loose again a close inspection of the pivots.   The wobble may be due to manufacture but again check the rim is not loose on the staff to be sure. It’s just a question of being patient and going through the likely causes one by one to eliminate them .    All the best

[MarkF]

Thanks for all the help this far. Last question  

 After removing and oiling the balance jewels I had a hell of a time getting the diashock spring into place, and the jewel and capuchon fell out a number of times (though always stayed intact). Given that the jewel did not separate from the capuchon, can I assume it is still oiled or would all of that handling suggest I should re-oil it?

 

[watchweasol]

Hi. Re clean and re oil ther could be any amount of microscopic contamination.