Fascinating to read this from diagnostics through to repair. Somehow feel like I've walked into the brain of a watchmaker and shouldn't be here. Thanks JimInOz!

 

The cost of any parts and postage, and a donation to cover oils/consumables, whatever the owner is comfortable with and whatever he feels is value for the work done.

Unlike a professional watchmaker, I don't have to earn my bread and butter this way, and if the "profits" cover tools etc, or I get paid in kind I'm happy with that.

Still can't get the beat error below 0.3m/s, and amplitude is a bit low, even for a Seiko, but I think that's the generic replacement mainspring.
Low amplitude is a small price to pay compared with the cost of a new OEM item, even if you can find one.

 

What happened to the hairspring? Why was it messed up?

 

My guess is that after so many decades of service, it had to be replaced.

 

Mainspring.

The tired and "set" original mainspring was replaced with a generic spring made by Generale Ressorts. While not an exact match to the original, it is as close as possible in height/thickness/length, but cannot duplicate precisely the characteristics of the original.

 

Well done mate, another lovey timepiece put back into really nice condition

 

Hi Jim

Good work and the watch is transformed

Your amplitude is low though, if that's at full reserve and in horizontal. I had the 6138 shown below in about a year ago and it also looked considerably better after the service and a new crystal. Which mainspring did you use and did you get a good power reserve?

I measured the one that came out and it was 1.05 mm high, 0.12 mm strength and about 420 mm long. The barrel is 11 mm diameter. I tried one spring that was a bit shorter but settled on the mainspring for an ETA 2892 - in fact, a generic GR25341X which is 1.05 x 0.115 x 420 x 10.5 so slightly weaker but, who knows what an original Seiko is, as the mainspring I measured was likely not original. This was a good movement and performed well at the end with just under 250 degrees in horizontal and a power reserve of 44 hours (my notes say this is slightly low and should be 45 hours but, I never found a proper specification) which I was happy with as it didn't need anything else. As you note, these don't run great amplitudes though.

Keep well, Chris

Before:


After:

 

Hi Gents,

Reading this I thought to myself "I wonder what springs I was using back when I was servicing these?" So I dug up some disks where I've stored my older photos and had a look. Going back to 2011 here and the first 6139 I came across wasn't a lot of help, since it appears I was found a genuine spring at that time:


Seems very helpful that they also stamp the part number on the shipping ring, which is unusual:


So onto another 6139 I serviced that year, and apparently I couldn't get a genuine spring, and this is what my local material supplier offered as a generic equivalent:



So Chris, I am guessing that based on this, the spring you removed from the watch you serviced was pretty much right. This one is a little wider, but strength and length are about the same. The fact that this one is made 1.08 wide tells me it is probably a pretty faithful reproduction, since that is an unusual width (normally they jump from 1.05 to 1.1, with nothing in between).

Note the 6138 and 6139 use the same spring, as do some others...

Hope this helps.

Cheers, Al

 

Good information Al, thanks. Yes, that's basically the same but in an odd height. I don't do many of these so, always interesting to see what's on offer. I have a collector who has half a dozen of these he wants me to look at so, I might end up doing some more. Apart from the central chronograph runner/4th wheel unavailability and the barrel bearing wear in the plates they are not bad to work on but, I'll spread them out over some months if I do them.

Cheers, Chris

 

Sorry for using hairspring, i should have said balance spring. in the beginning it was not looking so happy, Was wondering about the beat error and balance spring.

 

To @Archer and @ChrisN, thanks for the tips on mainsprings guys.

It seems that the only currently available generic replacement is the GR2534X, which I have used.
So while the amplitude isn't great the watch has been keeping good time for the last few days and it's 99% better now than what it was and I'm going to call this one complete.



I'm now looking at a 6309 with poor power reserve. When manually wound it will run for 48 hours. I also noticed manual winding (via ratchet screw) was stiffer than normal and the bridle slip was very noticeable.

I put the autowinder back on and while it rotated freely from "unwound" it quickly tightened up and rotating the watch as a wearer would resulted in practically no movement of the rotor.

My first suspect is an overly strong mainspring so I'll investigate that.

Other than that, any ideas?

 

Jim - Seikos are very efficient winders, so barring any defect in the automatic winding section, then a strong mainspring is certainly a possibility. You noted it felt heavy to wind, so it's either that or something else is binding...let us know what you find when you get it apart.

 

To be continued.

 

For a 6139 you should be getting around 230 at full wind. Seiko state that at full wind, in the hanging positions the amplitude shouldn’t be below 180 degrees. These movements were designed to run at a lower amplitude and they work well.

As far as servicing goes, they are relatively easy to do and end up performing pretty well. The biggest issue is making the timing adjustments. You move the regulating pins the smallest amount and the change is massive! I find that the pallet stones tend to have a very deep full lock and that contributes to the low amplitude.

The other thing is that the pivots is the train wheels are usually in very good condition and not too many parts need replacing.

 

Getting your hands on OEM 401615 mainsprings is pretty hard and very expensive.

Can I ask which aftermarket mainsprings you use and what sort of amplitude are you achieving?

 

I’m happy if I get around 230 at full wind in the flat positions. As far as mainspring go, I usually leave the original in there if they are in good shape. I find most of the time they are in good shape. I use the same supplier as Archer Watches so those are my go to if I need a new one. But I have old movements floating around that I pilfer from too.

I usually add a jewel for the third wheel and that helps with performance a little.

For the 6105 I completely jewel the train and that makes a huge difference.

 

Thanks for the information.

Any details on what size jewel you use and a supplier or do you get it from a donor movement?

 

Me too. Everytime I see these I know... I'm not a real watch guy, these watchmakers are!!!

 

Really enjoyed your photos and admire your ability to service the Seiko movement.

I have a 6138-8020 Panda and there is no denying the popularity of these vintage models are on the rise. Although the 6139 line of single register chronographs do get most of the recognition. Both movements are rugged and well built and I’ve heard that most of the problems mechanically are with the push buttons.

Once again, blown away by your talent, and the end result is absolutely stunning.