Seiko 7s26 runs fast at night

[Spencelayh]

I have a Seiko snk809k2 I bought second hand, faulty just as a project. The ratchet wheel had a tooth missing. The balance spring was a very peculiar shape and the watch needed a good clean and lube. I should have just dropped a new movement in but I like a bit of a challenge. I have spent time on it now and then and have got it to the point that it runs reliably.  It doesn't keep good time though. When worn, through the day it stays correct to within a minute. When I take it off , if I leave it face down it gains about 5 mins during the night. If I leave it face up it gains about an hour and a quarter. I had to fit a new spring to get it to run through the night and the rotor fell to bits the other day. I put one in from a 7s26a, not quite the same but it seems to wind ok.

 

Has anyone any thoughts about this watch (apart from I am an idiot and should just bin it) ?

 

[rodabod]

Possibly: dirty hairspring, deformed hairspring, incorrectly adjusted stud/indexing pins.

[rodabod]

Start by inspecting the hairspring breathing under strong magnification and good light.

[khunter]

magnetized maybe? that would cause it to take on a "peculiar" shape

[jdm]

6 minutes ago, khunter said:

magnetized maybe? that would cause it to take on a "peculiar" shape

The "peculiar" shape was before the OP replaced a "new spring" - what is that? All in all a confusing description, no timegrapher pictures (better say, no timegrapher all at), so any guess is good.

[khunter]

37 minutes ago, jdm said:

The "peculiar" shape was before the OP replaced a "new spring" - what is that? All in all a confusing description, no timegrapher pictures (better say, no timegrapher all at), so any guess is good.

from what his description says I think he's talking about the main spring, as it seems to "wind ok".....maybe I'm mis-reading it

[Spencelayh]

Hi guys, thanks for the interest I had the impression from the state of the watch it had had a very hard time . The broken ratchet wheel and the balance were discovered at the beginning. I have noticed that whenever anyone decides to "Have a look " inside a watch it seems to involve poking at the balance until the spring is knackered. After replacing both of these parts it seemed to run but never seemed to run through the night.So after replacing the usual parts for winding issues I changed the main spring. Now it runs all night and goes like a train! After reading the suggestions put on earlier I decided to check the balance in case I had damaged the new one. It seemed ok but as I had it to pieces thought I would look around in case any foreign bodies had ended up in there. I took off the main bridge and checked under there, all looked ok and reassambled it. I never tighten those screws fully until I am sure all is well. The movement started running so I started tightening the screws and it stopped again, eased them off and it goes again. I have a scrap movement so I am going to swap the bridge and see what happens .

[jdm]

It's very difficult to get an old and troubled 7S26 to run acceptably. As you mentioned, multiple parts can be defective and lots of subtle issues accumulate. I recommend that you get yourself a timegrapher or equivalent app and look at amplitude and pattern. When these stay poor after repeated attempts the only choice is to keep it for parts. All good for practice anyway.

[anilv]

If you have a spare main plate.. Fix the balance to that so that you can get the best view of the balance spring from all angles. The balance jewels must be installed of course. 

Inspect the pivots and pivot jewels  closely. Sometimes I take a photo using my phone with the Loupe over lens... That way you can zoom in closer. 

Good luck! 

[Spencelayh]

Thanks for all of the suggestions. I have looked at the telegraphed app, but a suitable microphone seems to be needed, any suggestions on that front.?

 

[jdm]

1 hour ago, Spencelayh said:

I have looked at the telegraphed app, but a suitable microphone seems to be needed, any suggestions on that front.?

Try the embedded or earbuds, someone reports good lock with these.