Eta 2783

[Marc]

This is one that I picked up a while ago to restore and send on its way.

 

 

A Cortebert 25 jewel auto probably from the 70's or early 80's. As you can see it was in need of a little TLC on the outside....

 

 

And by the look of it on the inside too.

 

 

With the back off the movement looks pretty clean. It's an ETA 2783, a good solid workhorse, and apart from a couple of light scratches to the rotor and auto wind bridge, it doesn't appear to have been abused.

 

 

With the auto bridge off the scratch can now be seen to extend to the ratchet wheel as well. Looks like someone slipped undoing the rotor screw and skated their screw driver almost to the edge of the movement. They must have been pushing quite hard.

 

 

I guess they didn't get as far as trying to remove the dial. All pristine under here.

 

 

Calendar works out of the way and layout of the key-less works exposed.

 

 

Dial side stripped out. Just the balance pivot setting to come out.

 

 

Flipped back over now and the balance and cock removed.

 

 

With the remainder of the bridges, and the barrel out, the going train layout is revealed.

 

 

This is the under side of the auto bridge with the reversing wheel cock removed to expose the two reverser wheels on the right, and two reduction gears on the left.

 

 

The fully stripped auto bridge. I think that this might be the missing centre post that Tim was referring to in his post on the ETA 2873.

 

 

And the balance and cock go back onto the main plate (minus the jewel settings) ready for the Elma.

 

 

That's everything out of the cleaner and ready to go back together.

 

 

The mainspring was in really good shape so after a very light application of grease, and a few dabs of 8213 in the barrel wall recesses it goes back into the barrel.

 

 

The balance jewels are then installed with a bit of 9010 and the free movement of the balance wheel checked. Also the state of the hairspring and it's proximity to the balance cock is checked. All is well here so the balance and cock come back off and go to one side whilst the rest of the train goes together.

 

 

Going train back in. I just love how bright and shiny it all comes out of the wash.

 

 

Barrel and bridges back in place. HP1300 for the barrel pivots, 9020 for the second wheel, 9010 for the rest.

 

 

With the ratchet wheel, crown wheel, and click in place I can now check the recoil on the escape wheel. All good.

 

 

Pallets back in place and lock and draw checked, then a touch of 941 on the exit pallet, transferred to the escape wheel teeth by gently working the pallet fork manually. Then drop in the balance, and off she goes.

It's then just a matter of reassembling the calendar works, key-less works, and the auto wind module, and the mechanics are done.

 

 

And there's a nice drop of ETA goodness to confirm that all is well.

 

 

A very gentle clean for the dial and hands, polishing of the case, and a new armoured crystal, and things look a whole lot better than they started.

 

I hope that this proves useful to somebody.

 

This has now had a 24 hour test drive and has managed to stay within a couple of seconds of spot on on the wrist. I really like the look of this one and it's a very comfy size, I almost decided to hang on to it but I just can't justify another at the moment, so it is now on eBay. If anyone is interested I will post up the item number although it should be easy enough to find.

 

Marc.

 

 

 

 

 

 

 

[Don]

Nice work and great detail on the walk through. Thanks for posting.

[BlakeL]

I want a microscope just for the pictures...

[bobm12]

Very nice pictures and walkthrough! Thank you!

[Marc]

I want a microscope just for the pictures...

 

No microscope required Blakel.

These pics were taken hand held on an ageing Canon PowerShot A720 IS compact digital camera fitted with a cheap Chinese LED ring light.

I use it set for macro focusing and in aperture priority (AV) mode with the aperture set to f8. If the shutter speed drops below about 1/40 sec then I use a small table top tripod.

The ring light is the real key as it allows you to get really close without casting a shadow on the watch.

 

 

Also, apologies for the late night typo. I referenced Tims post regarding his missing centre post; it should read 2783, not 2873.

[Geo]

Quality work as usual Marc! B)

[BlakeL]

No microscope required Blakel.

These pics were taken hand held on an ageing Canon PowerShot A720 IS compact digital camera fitted with a cheap Chinese LED ring light.

I use it set for macro focusing and in aperture priority (AV) mode with the aperture set to f8. If the shutter speed drops below about 1/40 sec then I use a small table top tripod.

The ring light is the real key as it allows you to get really close without casting a shadow on the watch.

 

 

Also, apologies for the late night typo. I referenced Tims post regarding his missing centre post; it should read 2783, not 2873.

 

I saw you recommend it in another post but for some reason I thought it was just an accessory for the microscope.  I'll have to give it a try since the light seems to diffuse well and not wash out the image like mine seems to do even if I bounce the flash.

[Scottster]

Nice walk through. I cleaned and serviced a 2783 this weekend that was in a Sandoz watch. Your walkthrough was a great help. Thanks again.

[Mark]

Excellent post Marc. Thanks for sharing :)

[clockboy]

Great job done Marc a nice watch brought back to life.

[xzqt]

Nice work.

[JoeJBP]

Really like this walk through. I may use this as a reference for my own servicing. Could anyone please explain escape wheel recoil? I haven't come across that before. 

Joe. 

[Marc]

Hi Joe,

escape wheel recoil is a good indication that frictional losses within the train are as low as possible.

If you re-assemble the train from the barrel through to the escape wheel (but not the pallet fork), then any torque applied to the barrel will be transferred through to the escape wheel which will spin.

In a theoretical frictionless system, winding a small amount of power into the mainspring would cause the escape wheel to spin in the correct direction until there was no stored power left in the spring, at which point the inertia of the spinning escape wheel (and the rest of the train) would keep the train turning in the same direction, unwinding the mainspring from its equilibrium state through the barrel arbor until the inertia of the spinning train is overcome by the force of the spring (now wound in the wrong direction), at which point the train would reverse and spin back in the wrong direction under the (reverse) power of the spring. This is the recoil that I was referring to.

In the frictionless system described above, the reverse running of the train would again go back through the equilibrium point of the mainspring and inertia would wind the spring up in the right direction until it overcame the inertia, and the system would oscillate for eternity (unless you want to get into hysteresis in the mainspring!!), however, in real life, friction bleeds energy out of the system so it stops.

Observing the way in which the system comes to rest can give you a clue as to the general health of the train. If it comes to an abrupt stop with no recoil and there is still torque in the mainspring (check the state of the click against the ratchet wheel) then friction within the train is high and may indicate something like a bent pivot or a damaged jewel. If it comes to a stop at the equilibrium position of the mainspring without any recoil then it may be worth double checking the cleaning, and possibly the end shake on the wheels through the train. It may also indicate the wrong size spring has been fitted as too tall a spring can bind slightly against the top and bottom of the barrel. However, on some older movements it could just mean that general wear, although not severe enough on any individual component to warrant its replacement, has added up through the train to prevent recoil.

Ideally though, on a half decent, properly cleaned movement in good order I would expect to see the escape recoil by maybe a couple of revolutions, which would indicate that all is well. I have actually seen double recoil before (where the escape wheel reverses, and then turns the right way again before stopping) but it is not common.

Apologies for the wordy answer, but you did ask 

 

[Cad101]

It was a wonderfully worded replay and explained it very well

[JoeJBP]

Great reply Marc, very well explained. 

While we're here, could you explain something about end shakes, specifically the amount of movement expected? It seems as though it's a matter of experience and judgement rather than measurement. I know how to test this and have checked it on my own watches without being sure exactly what I'm looking for. 

Joe. 

[Marc]

7 hours ago, JoeJBP said:

Great reply Marc, very well explained. 

While we're here, could you explain something about end shakes, specifically the amount of movement expected? It seems as though it's a matter of experience and judgement rather than measurement. I know how to test this and have checked it on my own watches without being sure exactly what I'm looking for. 

Joe. 

You're pretty much spot on with the experience and judgement thing.

End shake on the balance staff should be "perceptible but not measurable", so you should be able to tell that it is there but if you can measure it then it's too much. The same is about right for the pallet arbor.

The train wheels can have a bit more, with the escape wheel maybe somewhere between the train wheels and the balance staff.

That at least is the theory, in practice it really does just come down to your judgement.

De Carle (the first and probably most important book I read on watchmaking) put it in terms of layers of tissue. 3 layers or 0.03mm on the train wheels, 2 layers or 0.02mm on the escape wheel, and 1 thickness or 0.01mm for the balance and pallet. I always assumed that hand rolling cigarette papers were a more consistent substitute for tissue, but I have often found that you can't apply any hard and fast rules, and some watches run better more, and some with less. The only thing that is certain is that you need "some".

[clockboy]

End shake I find difficult to access through lack of experience. However for me when the watch on a timing machine shows a burst of snow when turning the watch from say dial up to dial down then end shake is the likely cause.

Adjusting to eliminate is another issue. I believe it is achieved but altering the depth of the jewel or jewels providing they are not damaged & the pivots are in good condition. On high end watches such as the Rolex the adjustment for the balance end shake is catered for via  tiny screws that allow adjustment to the height. Adjustment on the lower grade watches is a challenge by the fact the top cap jewels can not be moved but the lower one can with the aid of a jeweling tool.

 

Ps This my take on it anyway. Guys with more experience may well chip in on this one with their solutions.

 

 

[szbalogh]

1 hour ago, clockboy said:

Adjustment on the lower grade watches is a challenge by the fact the top cap jewels can not be moved but the lower one can with the aid of a jeweling tool.

I have also issues with my watch, possibly with the endshake. Its a cheap chinese movement. How can i change the cap jewels distance? 

[clockboy]

If it is possible to move them then they have to be moved precisely as tiny incrementle movements  make a lot of difference. 

Only attempt with the correct jeweling tools such as a Favorite or "SEITZ" Jeweling Tool

 

Mark has a vid showing how to change a jewel using one of these tools

 

[JoeJBP]

So I think my course of action is to check the end shakes on everything I do, get a feel for it and over time I suppose I will find faults relating to them. How common are they and what are the symptoms?

Thanks. Joe. 

[vinn3]

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" De Carle's"  book is my favorite,  especially on "end shake".  I took an elgin pocket watch  mvt.  apart  because it ocasionaly stopped.  underneath the  balance cock was a small piece of shim stock.   this was a poor way to adjust  "end shake".     p.s.  could not figure out how to enter above quote by MARC.

[clockboy]

I have come across the shim trick a few times. However normally it is because a new balance staff is a bit tight so instead of honing down the staff to fit correctly a shim under the balance cock is used. Also I have been told some put a shim under the far edge of the cock to tilt it a bit tighter to reduce end shake. Bodge methods such as the shim work around is not for me.However some do but it does pass on the problem to the next unsuspecting watch repairer. 

[szbalogh]

3 minutes ago, clockboy said:

I have come across the shim trick a few times. However normally it is because a new balance staff is a bit tight so instead of honing down the staff to fit correctly a shim under the balance cock is used. Also I have been told some put a shim under the far edge of the cock to tilt it a bit tighter to reduce end shake. The shim method is not for me but some don,t mind passing on the problem to the next unsuspecting watch repairer. 

Played with my Roskopf pocket watch yesterday a bit. "The book" says You can hear the impact of balance staff on the cap jewel if holding the movement to the ear and slowly tilting it. An yes it works. Used very thin cellophane layers to tilt the bridge sinc i dont have a proper lathe ... yet. Finally 3 layers were to much and with 2 layers i still could hear the balance hitting the jewels. This is a big movement with big parts, next time i take apart a smaller watch will try this method to check the endshake.

[Colditz]

On 4/12/2015 at 11:13 PM, Marc said:

This is one that I picked up a while ago to restore and send on its way.

 

 

A Cortebert 25 jewel auto probably from the 70's or early 80's. As you can see it was in need of a little TLC on the outside....

 

 

And by the look of it on the inside too.

 

 

With the back off the movement looks pretty clean. It's an ETA 2783, a good solid workhorse, and apart from a couple of light scratches to the rotor and auto wind bridge, it doesn't appear to have been abused.

 

 

With the auto bridge off the scratch can now be seen to extend to the ratchet wheel as well. Looks like someone slipped undoing the rotor screw and skated their screw driver almost to the edge of the movement. They must have been pushing quite hard.

 

 

I guess they didn't get as far as trying to remove the dial. All pristine under here.

 

 

Calendar works out of the way and layout of the key-less works exposed.

 

 

Dial side stripped out. Just the balance pivot setting to come out.

 

 

Flipped back over now and the balance and cock removed.

 

 

With the remainder of the bridges, and the barrel out, the going train layout is revealed.

 

 

This is the under side of the auto bridge with the reversing wheel cock removed to expose the two reverser wheels on the right, and two reduction gears on the left.

 

 

The fully stripped auto bridge. I think that this might be the missing centre post that Tim was referring to in his post on the ETA 2873.

 

 

And the balance and cock go back onto the main plate (minus the jewel settings) ready for the Elma.

 

 

That's everything out of the cleaner and ready to go back together.

 

 

The mainspring was in really good shape so after a very light application of grease, and a few dabs of 8213 in the barrel wall recesses it goes back into the barrel.

 

 

The balance jewels are then installed with a bit of 9010 and the free movement of the balance wheel checked. Also the state of the hairspring and it's proximity to the balance cock is checked. All is well here so the balance and cock come back off and go to one side whilst the rest of the train goes together.

 

 

Going train back in. I just love how bright and shiny it all comes out of the wash.

 

 

Barrel and bridges back in place. HP1300 for the barrel pivots, 9020 for the second wheel, 9010 for the rest.

 

 

With the ratchet wheel, crown wheel, and click in place I can now check the recoil on the escape wheel. All good.

 

 

Pallets back in place and lock and draw checked, then a touch of 941 on the exit pallet, transferred to the escape wheel teeth by gently working the pallet fork manually. Then drop in the balance, and off she goes.

It's then just a matter of reassembling the calendar works, key-less works, and the auto wind module, and the mechanics are done.

 

 

And there's a nice drop of ETA goodness to confirm that all is well.

 

 

A very gentle clean for the dial and hands, polishing of the case, and a new armoured crystal, and things look a whole lot better than they started.

 

I hope that this proves useful to somebody.

 

This has now had a 24 hour test drive and has managed to stay within a couple of seconds of spot on on the wrist. I really like the look of this one and it's a very comfy size, I almost decided to hang on to it but I just can't justify another at the moment, so it is now on eBay. If anyone is interested I will post up the item number although it should be easy enough to find.

 

Marc.

 

 

 

 

 

 

 

Hi Marc

Have to say marvelous sir. I am in the throws of servicing the same movement and your pics are just what I needed as my phone went flat while I was videoing the strip down. I now have a reference thank you. Is there an ETA service sheet for the 2783? I cannot find one on Cousins website or anywhere obvious.

Once again thanks

 

[Tudor]

2783 is covered in here...

Eta 2750, 51, 52, 63, 64, 69-1, 73, 76, 81, 83, 84, 89-1, 90-1, 91.pdf