Seiko 7002 Randomly going fast and then slow

[RyanGreerMcGilloway]

Hello there,

 

Ive had my clean and oiled watch with my refurbished balance ticking away nicely over the weekend keeping extraordinary perfect timing!  then suddenly whenever i looked down last night its been increasing and decreasing in time of about 20 Mins. i dont understand why.

 

 

[watchweasol]

Hi I should take a careful look at the balance oscillation and the balance spring coils are not intermittently sticking during operation.  You mention refurbished balance, what did you do.

[clockboy]

I would first check the balance & hairspring with strong magnification. Check that the H/spring is breathing evenly and all of the coils are not sticking together.

[oldhippy]

I would de-magnetize the whole movement. See if that helps. Just a tiny hair or speck of dirt can mess the timing up. 

[TheFixer]

Yes check the coils you may have some oil contamination.

[RyanGreerMcGilloway]

How would i gently clean the coils / hairspring as i dont have a ultra sonic clean and cant be bothered to take it all apart again. 

[clockboy]

37 minutes ago, RyanGreerMcGilloway said:

How would i gently clean the coils / hairspring as i dont have a ultra sonic clean and cant be bothered to take it all apart again. 

Remove the balance and submerge in a de-greaser & agitate (gently ) then blow dry holding the balance so you don't distort the h/spring. .Fit the balance back in situ & re-lube the cap jewels.

[oldhippy]

Use ronsonol lighter fluid. It is safe to use. It won't harm any parts of the balance. You can leave the balance in the stuff for days. Use a screw top container because it evaporates very quick.  

[RyanGreerMcGilloway]

Hi all, 

Thanks for your help!

 

Monday evening i gave the balance a little oil and blew out any bits & bobs through the movement with my bicycle pump. I also demagnetized the whole movement.

 

It seems to have worked perfectly until last night where i just noticed it had crawled 2 mins ahead and then i reset it and againt crawled 3 mins in the space of 10 mins. I had then removed the watch and sat it on the table until the morning where it had not increased anymore time. 

 

Is there any chance that this could be due to over winding the automatic movement or is that not a thing.  

[oldhippy]

No, you cannot over wind a movement, that is a myth. As I have said before you need to  demagnetize the complete movement. 

Bicycle pump.  You need a proper blower, Watch suppliers stock them, this is what you need. Bicycle pump is to strong and could damage the hairspring. 

 

[watchweasol]

Hi  Intermittent behavior like that, the prime suspect is as mentioned the balance spring rubbing or sticking and or the balance jewels dirty/cracked or worn. remove the balance assembly dismantle    ,clean and inspect as quoted and reassemble with a little oil on the je   wels and rebuild and re fit the balance. no oil on the fork. 

[meanoldmanning]

Hi all, 
Thanks for your help!
 
Monday evening i gave the balance a little oil.  

Explain this.


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[CaptCalvin]

Have you ruled out knocking? What does the trace look like on the timing machine? Amplitude?

Edited November 3, 2019 by CaptCalvin

[Nucejoe]

7 hours ago, CaptCalvin said:

Have you ruled out knocking? What does the trace look like on the timing machine? Amplitude?

Would much appreciate introduction to, or definition of   ,,,,banking,,,,    and elaboration on it, in this case.  

Working links to subjects of  banking. Re-banking. Over-banking   would be useful  indeed, as online search keeps turning unhosted pdf's . TIA

 

[Nucejoe]

The least would be to submerge in lighter fluid the balance+ cock ( attached) assembly. Demagnetize. 

Ultrasonic is kinda a laundry machine,  hairspring prep is an art. 

Best Regards   Joe. 

 

 

 

[CaptCalvin]

4 hours ago, Nucejoe said:

Would much appreciate introduction to, or definition of   ,,,,banking,,,,    and elaboration on it, in this case.  

Working links to subjects of  banking. Re-banking. Over-banking   would be useful  indeed, as online search keeps turning unhosted pdf's . TIA

 

Not much to say really. It's a symptom of excessive amplitude, the balance wheel swinging so wide it makes a complete revolution and the impulse jewel crashes into the opposite fork horn and bouncing back. This will cause the watch to periodically gain considerably. Use a weaker mainspring and/or heavier oil to remedy. Trace on timing machine would look something similar to this:

[Nucejoe]

26 minutes ago, CaptCalvin said:

Not much to say really. It's a symptom of excessive amplitude, the balance wheel swinging so wide it makes a complete revolution and the impulse jewel crashes into the opposite fork horn and bouncing back. This will cause the watch to periodically gain considerably. Use a weaker mainspring and/or heavier oil to remedy. Trace on timing machine would look something similar to this:

Thank you. I don,t think I have ever dealt with such a case, but then I hardly replace a mainspring and am pretty sure oils here are more of massey ferguson extract.  

Best 

[meanoldmanning]

The newest 7002 is over 20 years old and most you run into are pretty neglected. The several I’ve worked on can achieve pretty good amp, usually in the mid to high 200s but nothing much more, so I’d be inclined to rule out overbanking. Timegrapher traces would be helpful though

 

The barrel/arbor/ms is ‘sealed’ and intended to be replaced as a unit. The barrel can be opened but the equivalent GR mainspring is a bit weaker even than the OE.

 

The b/a/ms is no longer available but the unit intended for the 7S26b can be used and can still be found if you look

 

 

 

 

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