AS/ ESA/ETA 536-121

[Andyworks]

good morning

 

I have been restoring a Squale divers watch and have discovered that the coil on the circuit is knackered. I have trawled the internet for information and it seems like this is somewhat of a holy grail and no one stocks replacement circuits aor movements and if there is one for sale it is at a horrific cost.

 

I see that people fit ETA automatic ovements instead of quartz ones but again the guy I am repairing the watch for does not want to stretch that far. I have been trying to research alternative quartz movements but have not had much luck as the suggested ones are obsolete. Has anyone come across a suitable replacement before or has anyone got a spare electric circuit for this movement going spare?

 

Many thanks

 

Andy

[rogart63]

Think the circuit and coil for the 9362 work.  So check for a 9362 movement or a coil is easier then finding the hard to find 536.121 movement. 

Edited August 7, 2017 by rogart63

[Neileg]

I believe the ETA 955 is a substitute. These are sometimes available as NOS at reasonable prices. Lots of used ones and spares about as this movement featured in lots of watches. Often badged as TAG, Longines, etc. Can be GP or plain.
If you're sure it's the coil try a generic replacement.
Good luck, Neil


Sent from my iPhone using Tapatalk

[dinomartino1]

Early CWC G10 military watches use the ESA 536.121 and these are what people use on those as replacements

ISA 1198-103  easily found new.

1198-103.pdf

2.25mm stem height
90/150/20 hands
 

Second hand the for the ESA is 26 so will be to big

[rogart63]

Eta 955 won't work. That movement is to thin and has the wrong size hands. It's only the CWC  G10 s.k  fatboy that have the  536.121 movement. All the other normal thin g10 use the 955.112 or 955,114. 

Check for old Certina  quartz movements. They have a movement that is called 750. That is a ETA movement. 

Edited August 9, 2017 by rogart63

[Neileg]

Eta 955 won't work. That movement is to thin and has the wrong size hands.

Sorry, I was relying on web chatter. Didn't mean to mislead.
Cheers Neil


Sent from my iPhone using Tapatalk

[Andyworks]

Thank you for all the helpful suggestions. I am surprised by how many alternate movements can be used but never know how to find out about them. Is there a website or somewhere on for example ETA that will list successive movements in the same family that could be used? It would be so handy if there is such a site.

 

Andy

[vikramnarula]

Just came across this thread while researching about this particular movement . 

received a lot of NOS watches with the same movement . would be glad to share more pictures. 

do let me know if anyone needs some.

[Clayb]

After being issued with a CWC G10 in the 1980's I've aquired several and had the ESA 536.121 fail and sourced much of this information years ago before leaning how to effectivily strip and service mechanical movements and recently purchased a quartz testing unit. Knowing the sarcity of this this movement I collected spares but fine most of them don't show a decent pulse. Some have obvious coil damage and I'm now looking to resistance test the others since there will still be a pulse if it's a gear train problem which I now adept at sorting.

Given the coils are the weak link and quartz watch curcuits almost univerally use 1.5v batteries I'm wondering if the coil could be changed with one from another type of movement preferably ETA but possibly something else such as Ronda that supply replacement coils for their movements. Under ohms law  1.5v and a similar amount of torque(power) requirement, the amp and resistance parameters for say a 11.5"'  quartz movement chip and stepper motor aren't going to vary significantly so there must be a suitable coil avaliable somewhere that would work.

The hardest part would be soldering on the very fine wires but in practice this would mean just turning the existing solder pads molten to press in the wires. What are peoples thoughts on this because the no jewel ETA/ETS 536.121 and the amonst identical but IMO better 7 jewel ESA 9362 movements are rare, expensive but were very commonly used in many good circa 1980 watches   

[Nucejoe]

 e

Check this response by HSL.

In my neck of the woods, folks rewire watch coils on bench, make a DIY tool , a small motor the kind you see in toys, some sort of adaptor( hand made filed down to shape) to mount the coil core on and a role of wire, which I think most material houses carry.

Works even though not as nicely coiled as factory made ones.

Happy Christmas 

 

[Clayb]

17 hours ago, Nucejoe said:

 e

Check this response by HSL.

In my neck of the woods, folks rewire watch coils on bench, make a DIY tool , a small motor the kind you see in toys, some sort of adaptor( hand made filed down to shape) to mount the coil core on and a role of wire, which I think most material houses carry.

Works even though not as nicely coiled as factory made ones.

Happy Christmas 

 

it's interesting to hear this but the wire size and number of turns would be required and it would be a very delicate operation. Have you any idea of the sort of set up used to do this ie wire gauge number of turns resistance values etc.

[Nucejoe]

26 minutes ago, Clayb said:

it's interesting to hear this but the wire size and number of turns would be required and it would be a very delicate operation. Have you any idea of the sort of set up used to do this ie wire gauge number of turns resistance values etc.

I can ask how they came up with the specifications of wire.

From the top of my head, couldn't you measure electrical resistance of a good piece of coil wire? Measure its thickness?  etc.   Get help from electrical  engineers?   Post a thread on the subject? Join an electrical forum? Google for some read on the subject? 

Regs 

Joe

 

[rodabod]

I’ve replaced coils before by soldering, but personally wouldn’t bother trying to wind one as it’s so fine. Guitar pickup wire is much thicker and still delicate. If you are lucky and the break is on the outer, then you can unwind until you reach the break and then re-solder. 

[Clayb]

With the power (wattage) resistance ohms and voltage it can all be calculated it's just the very intricate and delicate nature of making such a small coil. I may try revarnishing a coil in the hope it seals potential scratchs how ever trying to replacing the coil on a ESA 536.121 seems to be the easiest approach. These old movements are fetching second hand prices similar to ETA 2824 mechanical movements that can be used as a direct replacement .