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Eta 7750 Service Walkthrough - The Industry Standard Chronograph

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ETA 7750 Service Walkthrough

 

 

The 7750 was first available in 1974, having been one of the first movements to be designed with the aid of a computer.  It's hard to believe that the 7750 is still the industry standard movement for chronographs considering it's history.

 

It was developed over 40 years ago by Valjoux, who was then a legendary movement maker that was part of the giant ASUAG conglomerate.  But by the end of 1975 production was stopped due to the onslaught of the Quartz Era, and the 7750, along with many other mechanical calibers, was abandoned.  Industry demand for this movement was so low that the stock produced in that 1 year manufacturing lasted until 1982!  Such was the devastation of cheap Japanese produced quartz watches to Swiss manufactures.

 

History may have forgotten the 7750 except for the local management at Zenith who ignored the orders by Valjoux to destroy the dies and equipment used to manufacture the 7750, instead hiding the equipment away from corporate eyes.

 

You can find many more fascinating facts about this caliber online, and it's well worth the read.

 

...................................................

 

This walkthrough will be very detailed, and I hope this will give people the courage to tackle this movement.  I've serviced quite a few calibers, and this is one of the most beautiful, with a very logical layout. 

 

ETA7750 Tech.PDF

 

If you have built your skills with basic movements, and become proficient in servicing them, I would highly recommend this movement to be your first chronograph to tackle.

 

post-246-0-27986000-1433648016_thumb.jpg

 

Lets begin.

 

DEMAGNETIZE THE MOVEMENT BEFORE DISASSEMBLY.

 

Remove the Day Indicator and store it in a safe place where it won't be damaged.

 

post-246-0-58828400-1433648019_thumb.jpg

 

Unscrew (0.8 Driver) the Jumper Maintaining Plate and remove it.

 

post-246-0-19292900-1433648022_thumb.jpg

post-246-0-54454300-1433648024_thumb.jpg

 

Do the same for the Date Indicator Maintaining Plate

 

post-246-0-47403800-1433648027_thumb.jpg

post-246-0-49979200-1433648029_thumb.jpg

 

Carefully remove the Jumpers Spring, holding it with a piece of pegwood so it doesn't ping away.

 

post-246-0-78606500-1433648032_thumb.jpg

 

Next remove the jumpers for the day and date.

 

post-246-0-64532900-1433648034_thumb.jpg

post-246-0-92871200-1433648036_thumb.jpg

 

The jumpers differ from one another, so here is a reference photo so you can see the difference.

 

post-246-0-58860800-1433648047_thumb.jpg

 

Remove the Date Indicator and place it in a safe place where it won't be damaged.

 

post-246-0-85720000-1433648050_thumb.jpg

 

The last piece to remove on the Date Platform is the Double Corrector

 

post-246-0-38594500-1433648053_thumb.jpg

 

Now unscrew (1.4 Driver) the Date Platform and gentle pry it from the movement.

 

post-246-0-97083500-1433648054_thumb.jpg

post-246-0-78907200-1433648056_thumb.jpg

 

Be careful when removing this plate, as there is a fine spring pressed into the plate that can be easily damaged.

 

post-246-0-95993700-1433648059_thumb.jpg

post-246-0-48417700-1433648061_thumb.jpg

 

Here is a reference photo of the screws that hold the Date Platform.

 

post-246-0-32806300-1433648058_thumb.jpg

 

Remove the Hour Hammer Spring, once again using the pegwood to hold the spring while removing the tension.

 

post-246-0-85283800-1433648063_thumb.jpg

 

Here is a reference photo of the correct orientation of the spring.

 

post-246-0-99376900-1433648064_thumb.jpg

 

Remove the Hour Counter Lock.

 

post-246-0-19035300-1433648082_thumb.jpg

 

Remove the Hour Hammer Operating Lever.

 

post-246-0-35006100-1433648085_thumb.jpg

 

Next is the Hour Hammer, be careful when removing this item so as not to damage the Hour-Counting Wheel.

 

post-246-0-40289900-1433648087_thumb.jpg

 

Now remove the Hour-Counting Wheel.

 

post-246-0-66449600-1433648089_thumb.jpg

 

Remove the Date Indicator Driving Wheel

 

post-246-0-15324700-1433648092_thumb.jpg

 

Remove the Day Star Driving Wheel

 

post-246-0-57273800-1433648094_thumb.jpg

 

Then remove the Intermediate Calendar Driving Wheel

 

post-246-0-92133000-1433648096_thumb.jpg

 

Remove the Hour Wheel

 

post-246-0-22782100-1433648099_thumb.jpg

 

Then the Minute Wheel

 

post-246-0-66133600-1433648101_thumb.jpg

 

Remove the Cannon Pinion, which does not require a puller.

 

post-246-0-18248900-1433648104_thumb.jpg

 

The last component to be removed on this side of the Main Plate is the Driver Cannon Pinion.

 

post-246-0-57539900-1433648121_thumb.jpg

 

To lift the Driver Cannon Pinion I used what Mark used, a set of hand lifter from Horotec (MSA05.007); but

you can also use a Presto Tool (30636-1) which will also work well.

 

post-246-0-02888400-1433648124_thumb.jpg

 

The dial side of the movement is now complete disassembled.

Flip the movement over and unscrew (1.5 Driver) the Oscillating Weight.

 

post-246-0-16326900-1433648126_thumb.jpg

post-246-0-93509900-1433648127_thumb.jpg

 

To remove the Hammer Spring lift it up gently over the automatic work and move it inwards.

This will move the tail of the spring in a clockwise motion to the opening in the slots, which will free the spring.

 

post-246-0-31654400-1433648131_thumb.jpg

 

Slide out the Clutch Spring.

 

post-246-0-98364000-1433648133_thumb.jpg

 

Here is a reference photo of this spring, and it's orientation.

 

post-246-0-21582600-1433648135_thumb.jpg

 

Remove the screws (1.4 Driver) for the Automatic Device Bridge, and gently pry it loose.

 

post-246-0-03443800-1433648137_thumb.jpg

post-246-0-05634800-1433648139_thumb.jpg

 

Here is a reference photo of these screws for the bridge.

 

post-246-0-79340300-1433648140_thumb.jpg

 

Once the Automatic Bridge has been removed, the two wheels for the automatic work are able to be removed.

Below is a reference photo of how the sit inside the bridge.

 

post-246-0-90338600-1433648153_thumb.jpg

 

We now begin to disassemble the chronograph section of this movement.

Begin with removing the Hammer, 2 Functions.

 

post-246-0-84473000-1433648157_thumb.jpg

 

Next remove the Clutch 60s, 2 Functions.

 

post-246-0-79687800-1433648162_thumb.jpg

 

Then remove the Minute-counting Wheel, 30min.

 

post-246-0-86197600-1433648173_thumb.jpg

 

Remove the Chronograph Wheel 60s, 30min.

 

post-246-0-10188000-1433648177_thumb.jpg

 

Gently lift out the Oscillating Pinion, 60s.

 

post-246-0-67313200-1433648180_thumb.jpg

 

Here is a reference photo of the orientation of this pinion.

 

post-246-0-40902000-1433648182_thumb.jpg

 

Unscrew (1.4 Driver) the Chronograph Bridge and gently pry it off the Train Wheel Bridge.

 

post-246-0-69386400-1433648184_thumb.jpg

post-246-0-93893700-1433648187_thumb.jpg

 

Remove the Ratchet Driving Wheel.

 

post-246-0-92792500-1433648190_thumb.jpg

 

Remove the Chronograph Wheel Fiction.

 

post-246-0-58852500-1433648204_thumb.jpg

 

Unscrew (1.4 Driver) the Operating Lever, 2 Functions.

 

post-246-0-54528300-1433648207_thumb.jpg

post-246-0-51477500-1433648209_thumb.jpg

 

Unscrew (1.4 Driver) the Lock, 2 Functions.

 

post-246-0-87002300-1433648211_thumb.jpg

post-246-0-77646600-1433648213_thumb.jpg

 

Next remove the Minute-counter Driving Wheel, 30min.

 

post-246-0-40810200-1433648217_thumb.jpg

 

Slide out the Operating Lever Spring, 2 Functions.

 

post-246-0-82379800-1433648219_thumb.jpg

 

This spring can be fitting in both directions; but only 1 way is correct.

Here is a reference photo of it's correct orientation.

 

post-246-0-29427600-1433648221_thumb.jpg

 

Remove the Switch.

 

post-246-0-81487500-1433648223_thumb.jpg

 

Here I digress from the order the SwissLab document illustrates the order of removal.

They show to remove the Chronograph Cam before removing the Hammer Cam Jumper.

This in my opinion is not the best way, as all the force from the jumper is pressing on the cam whilst your trying to remove it, and could lead to damage.

Instead I move the Chronograph Cam until it reaches the notch as shown in the photo below.

 

post-246-0-72569200-1433648225_thumb.jpg

 

Then lift the Hammer Cam Jumper up to the top of the Chronograph Cam, which will release it's tension.

Then, just as you removed the previous hammer, rotate the jumper to the opening in the slots, which will free the spring.

 

post-246-0-05611700-1433648241_thumb.jpg

 

Now you can unscrew (1.4 Driver) and remove the Chronograph Cam safely without tension on it.

 

post-246-0-51216400-1433648244_thumb.jpg

post-246-0-49334100-1433648246_thumb.jpg

 

RELEASE THE MAINSPRING TENSION

 

post-246-0-47640700-1433648248_thumb.jpg

 

Once the tension has been released, unscrew (1.4 Driver) and remove the Balance Cock.

 

post-246-0-71027500-1433648250_thumb.jpg

post-246-0-32493100-1433648253_thumb.jpg

 

Then unscrew (1.4 Driver) the Pallet Bridge and remove the bridge and Pallets.

 

post-246-0-55146800-1433648255_thumb.jpg

post-246-0-89586800-1433648257_thumb.jpg

post-246-0-34580600-1433648259_thumb.jpg

 

Unscrew (1.2 Driver) and remove the Ratchet Wheel.

 

post-246-0-85422000-1433648261_thumb.jpg

post-246-0-04880100-1433648280_thumb.jpg

 

Then remove the Crown Wheel.

 

post-246-0-10263600-1433648283_thumb.jpg

post-246-0-83522800-1433648284_thumb.jpg

post-246-0-14267600-1433648286_thumb.jpg

 

Unscrew (1.4 Driver) the Train Wheel Bridge and gently pry it off the Main Plate.

 

post-246-0-67640300-1433648287_thumb.jpg

post-246-0-47082200-1433648289_thumb.jpg

 

Note that one of the screws is under the Operating Lever.  This needs to be moved out of the way to access this screw.

 

post-246-0-26416300-1433648291_thumb.jpg

 

The last level of this movement contains the train.

Here is a reference photo of the wheel locations.

 

post-246-0-92755200-1433648292_thumb.jpg

 

Remove the Stop Lever.

 

post-246-0-34014300-1433648295_thumb.jpg

 

Remove the Great Wheel.

 

post-246-0-71741700-1433648297_thumb.jpg

 

Here is a reference photo of the underneath of this wheel.

 

post-246-0-90904700-1433648314_thumb.jpg

 

Remove the Third Wheel.

 

post-246-0-34353800-1433648318_thumb.jpg

 

Here is a reference photo of the underneath of this wheel.

 

post-246-0-64483400-1433648319_thumb.jpg

 

Remove the Second Wheel.

 

post-246-0-16363000-1433648323_thumb.jpg

 

Here is a reference photo of the underneath of this wheel.

Note this has the long lower pivot.

 

post-246-0-61604300-1433648324_thumb.jpg

 

Remove the Escape Wheel.

 

post-246-0-22620300-1433648327_thumb.jpg

 

Here is a reference photo of the underneath of this wheel.

 

post-246-0-44141700-1433648328_thumb.jpg

 

Then remove the Barrel.

 

post-246-0-90626600-1433648330_thumb.jpg

 

This completes the removal of the train.

Flip the movement over so we can complete the disassembly by removing the keyless work.

 

post-246-0-52840200-1433648332_thumb.jpg

 

Firstly, release the tension from the Setting Lever Jumper.

 

post-246-0-65232500-1433648334_thumb.jpg

 

Then unscrew (1.2 Driver) and remove the Setting Lever Jumper.

 

post-246-0-05634900-1433648353_thumb.jpg

post-246-0-96279200-1433648355_thumb.jpg

 

These are unique screws with pointed ends, and below is a reference photo of them.

 

post-246-0-57259700-1433648357_thumb.jpg

 

This will also remove the Intermediate Setting Wheel.

 

post-246-0-07099000-1433648359_thumb.jpg

 

Next remove the Setting Wheel

 

post-246-0-32135200-1433648361_thumb.jpg

 

Then remove the Yoke.

 

post-246-0-56713500-1433648363_thumb.jpg

 

Remove the Setting Lever.

 

post-246-0-00474600-1433648366_thumb.jpg

 

Remove the Rocking Bar.

 

post-246-0-41985500-1433648368_thumb.jpg

 

Now pull out the Stem.

 

post-246-0-43994600-1433648370_thumb.jpg

 

Once the Stem is removed the Winding and Sliding Pinion should fall out of the movement onto your work mat.

 

post-246-0-81761800-1433648372_thumb.jpg

 

Disassembly of the 7750 is now complete

 

post-246-0-57367800-1433648385_thumb.jpg

 

If you've come this far, congratulation on completing the disassembly.

Make sure you pegwood all the jewels and reinstall the Balance back onto the movement for cleaning.

 

post-246-0-06671100-1433648388_thumb.jpg

 

Assembly of the movement will be posted as soon as I complete the write-up.

 

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Excellent walkthrough again Lawson. I am interested in your assembly as there are a few sequences that can be adopted. i.e. I could not get the clutch spring fitted using the Eta assembly sequence I found fitting the spring before the bridge far easier.

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WOW!

What a sterling job Lawson. You've just set the bar that walkthroughs so will be compared with in the future. :)

You should start producing "Haynes" type manuals for horologists, they would be best sellers!

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Thanks for the positive feedback guys.  Editing the photos and writing up the walkthrough is far more difficult then the service on this movement. :p

 

I had to rebuild the software from scratch on a friends PC today, so that put me a little behind in this service, but I'm back into it now.

Parts are in the cleaning machine as I type this up, so the assembly and write-up shouldn't be far off, Lord willing.

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:bow:

 

Thanks mate :)

But all praise goes to my Lord and Saviour, Jesus Christ, for giving me the gift of being able to do this work and write-ups for you guys.

My hope is that they inspire others to "give it a go" like I did 11 months ago, and not be fearful of a challenge.

 

The reward that comes from succeeding and seeing a movement come to life are hard to put into words.

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The movement service is complete, and I'm doing the write-up now.

 

But just as a teaser, here's how the movement looks on the Timegrapher straight after I'd finished the service .... totally UNADJUSTED :)

 

post-246-0-39252600-1433760665_thumb.jpg

 

I'll adjust the timing to COSC standards another day ... I wanna get the assembly write-up posted tonight if possible.

 

 

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Awesome work. I just bought a 7750 and will start disassembly soon. Your walk of the disassembly is a great help. I can't thank you enough. I can't wait to see the rest.

Thanks again.

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Awesomeness in all splendor for a walkthrough! Very nice job and much raising the bar for walkthroughs! Very solid and desired movement to know in depth...great choice!

 

Thank you Lawson for putting the time into this!

 

Cheers,

 

Bob

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Thanks guys for all the positive feedback on this walkthrough.

Please feel free to post negative feedback, I'm here to learn as well, and welcome negative constructive comments from those who have years of experience with this movement.

 

I must apologies for the delay on posting the assembly, but I didn't realize just how long it would take to create all the pictures and do the write-up.

 

 

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ETA 7750 Walkthrough

Part 2

 

Assembly

 

Now we come to assemble the movement.

Here are the lubricants that will be used.

 

post-246-0-89966100-1433857024_thumb.jpg

 

Now nothing creates more discussion and controversy than which lubricants should be used on movements in various applications.

This is how I approach it ... your choices may vary.

 

The 7750 I am servicing here is a "Top Grade" ETA movement made for TAG, which would normally be cased with a display back.

Because of this I will be using Molykote DX instead of Jismaa 125 or 9501 grease for areas that will be seen.  As their lubricating qualities are very close, my choice of using Molykote DX is purely for ascetic reasons, as its less visible to the eye, then the bright colours of the 9501 and Jismaa 125.  You will notice that Molykote DX is recommended in the 7750 PDF; yet on the SwissLab documentation it states to use Jismaa 125, so all these lubricates are recommended and safe to use.

 

If this was a "Standard" or "Elabore" Grade movement with a full metal caseback, then I'd just go with the SwissLab recommendations, or 9501 for ease of servicing.

 

With all that being said, here is the Lubrication Index for this walkthrough.

 

post-246-0-64981800-1433857026.jpg

 

Housekeeping

  • Make sure your work area has been wiped down to remove any dust, and clear away any unneeded items from around your workspace.
  • Inspect your Screwdrivers and Tweezers, and dress them up if needed.  There is nothing worse than marring a screwhead, or have components ping from your tweezers because they need to be re-dressed.
  • Put on some finger cots, or latex gloves.  Personally, I use only one latex glove on my left hand, as any manipulation with my right hand will be done with my old trusty customized Dumont Brass #4 tweezers. NEVER touch cleaned parts with bare hands, this will leave prints and tarnish the finish over time.
 

We begin with the parts fresh from cleaning.

Try and arrange them in a logical order to start with, this will save you time fishing for parts later on.

 

post-246-0-69587000-1433857030_thumb.jpg

 

The 7750 has 7 types of screws, and you'll need 4 sizes of screwdrivers - 0.8, 1.2, 1.4, 1.5mm

1) Date Platform, Crown and Ratchet Wheel Screws

2) Setting Lever Spring Screws (Note the pointed ends)

3) Hammer and Cam Screws

4) Oscillating Weight Screw (Single Screw with the short thread)

5) Pallet Fork, Main Plate, Chronograph Plate, Automatic Work Plate Screws

6) Screws for the Jumper Maintaining Plates

7) Single longer screw for the Balance Cock

 

I like to arrange all the screws in groups like this, that way they are quick to find, and mismatching screws can't happen.

 

post-246-0-29389500-1433857033_thumb.jpg

 

One more thing to note on this assembly walkthrough, is that I started by using the 7750 plastic movement holder.

I quickly however changed to a Bergeon 4040 movement holder, and found this much better when it came time to fit the plates and align pivots to their jewels.

I'd suggest you use the Bergeon 4040 holder right from the get go.

 

Lets begin!

 

Place the Barrel on the Main Plate

 

post-246-0-85753900-1433857035_thumb.jpg

 

Next is the Escape Wheel

 

post-246-0-86340200-1433857038_thumb.jpg

 

Followed by the Second Wheel, which has the long pivot for the sub-dial hand.

 

post-246-0-20897500-1433857041_thumb.jpg

 

The Third Wheel is next to be installed

 

post-246-0-44903500-1433857043_thumb.jpg

 

With the last wheel in the train being the Great Wheel.

 

post-246-0-36187800-1433857046_thumb.jpg

 

Place 2 small spots of D5 as shown, so the Stop Lever will have a smooth action.

 

post-246-0-54161200-1433857048_thumb.jpg

 

Install the Stop Lever.

 

post-246-0-83470500-1433857061_thumb.jpg

 

Now install the Barrel/Train Bridge. (1.4 Driver)

Make sure all pivots are located correctly and the train is free spinning BEFORE tightening down.

Once tightened down check end shake.

 

post-246-0-78155300-1433857065_thumb.jpg

 

Install the Crown Wheel

 

post-246-0-28124500-1433857068_thumb.jpg

 

Then the Crown Wheel Core and screw down (1.2 Driver).

 

post-246-0-79734400-1433857071_thumb.jpg

 

Install the Ratchet Wheel and screw down (1.2 Driver).

 

post-246-0-17590100-1433857074_thumb.jpg

 

Once this is done, using a 1.2 Driver, turn the screw on the Ratchet Wheel a 1/4 of a turn to add energy to the Mainspring, and check the free running of the train.

 

 

post-246-0-85321800-1433857074.jpg

 

 

Next is the keyless work.

 

Lubricate the Winding and Sliding Pinion as shown below.

Also add a spot of 9501 to the Main Plate where the Winding Pinion will come in contact.

 

post-246-0-43970500-1433857077_thumb.jpg

 

Be sure when installing he Sliding Pinion that it's seated properly on the Stop Lever

 

post-246-0-39781300-1433857079_thumb.jpg

 

Install the Sliding Pinion

 

post-246-0-62356200-1433857081_thumb.jpg

 

Install the Winding Pinion

 

post-246-0-88945100-1433857083_thumb.jpg

 

Lubricate and install the Stem.

 

post-246-0-23430300-1433857101_thumb.jpg

post-246-0-79140900-1433857104_thumb.jpg

 

Next is the Driver Cannon Pinion.

This is one area that needs a lot of lubrication, as it will bind and damage the movement if it becomes dry.

 

post-246-0-26438300-1433857106_thumb.jpg

 

To install the Driver Cannon Pinion I use a Horotec Hand Fitting Tool MSA 05.011

 

post-246-0-58025200-1433857107_thumb.jpg

 

Once properly lubricated, install the Driver Cannon Pinion

 

post-246-0-10432500-1433857110_thumb.jpg

 

Before installing the Rocking Bar, lubricate the points on the spring.

 

post-246-0-75681600-1433857111_thumb.jpg

 

Install the Rocking Bar.

 

post-246-0-92851700-1433857113_thumb.jpg

 

Install the Setting Lever

 

post-246-0-25456400-1433857116_thumb.jpg

 

Install the Yoke.

 

post-246-0-26690700-1433857118_thumb.jpg

 

Place the Setting Wheel on it's post.

 

post-246-0-34050800-1433857120_thumb.jpg

 

Construct the Setting Lever Jumper with the Intermediate Wheel

 

post-246-0-81811200-1433857138_thumb.jpg

 

As noted above, the screws for the Setting Lever Jumper are the ones with the pointy threaded ends.

 

post-246-0-07853800-1433857141_thumb.jpg

 

Be sure to lubricate position points on the setting bar before you lever it into place.

 

post-246-0-81591500-1433857142_thumb.jpg

 

Install the Setting Lever Jumper / Intermediate Setting Wheel.

 

post-246-0-36752600-1433857145_thumb.jpg

 

The keyless work is now complete, check it is functioning correctly, then turn the movement over.

 

 

post-246-0-10934200-1433857146.jpg

 

 

Once the movement is turned over install the Pallet Fork.

 

post-246-0-31923000-1433857149_thumb.jpg

 

Then install the Pallet Bridge.

Once the bridge is in place, give the mainspring a few winds and check the free movement of the Pallet BEFORE

screwing it down (1.4 Driver)

After tightening down check the end shake.

Use 9415 on the Exit Pallet Stone to lubricate the escapement.

 

post-246-0-74828800-1433857152_thumb.jpg

 

Replacing the Balance and oiling the Incabloc Jewels is next.

Place the Balance back onto the movement, checking that it's free running before tightening the screw (1.4 Driver).

Once tightened check side shake and end shake is correct.

 

post-246-0-59326200-1433859979_thumb.jpg

 

Remove the Incabloc Jewel, and then remove the Balance.

Note the longer screw that is used to secure the Balance Cock.

 

post-246-0-16256300-1433857154_thumb.jpg

 

Cleaning them carefully by soaking in a container with Lighter Fluid ... I use Zippo Fluid.

 

post-246-0-58065300-1433857155_thumb.jpg

 

Once clean, dry the Balance and Incabloc Jewel and place a drop of 9010 on the Jewel as shown below.

Make sure it covers at least 1/3 to 1/2 of the jewel, without the oil touching the sides of the jewel.

 

post-246-0-83365100-1433857156_thumb.jpg

 

Give the movement several winds to add some power to the Mainspring.

Replace the Balance back on the movement and refit the Incabloc Jewel.

Check that the Balance is oscillating freely.

 

post-246-0-23816900-1433857183_thumb.jpg

 

Then repeat the process for the jewel only on the Main Plate.

 

post-246-0-69622300-1433857179_thumb.jpg

 

Next to be installed is the Hammer Cam Jumper. Here is my method for installation.

Place the Hammer Cam Jumper into position, turning it clockwise to lock it into the slots.

Then place the Chronograph Cam on it's post, so that it rests on top of the cam jumper ... as shown below.

 

post-246-0-75808000-1433857185_thumb.jpg

 

Then while holding the arm of the cam jumper back, seat the Chronograph Cam into position and affix the screw (1.4 Driver)

 

post-246-0-99980600-1433857187_thumb.jpg

 

Install the Switch

 

post-246-0-46492600-1433857190_thumb.jpg

 

Insert the Operating Lever Spring, 2 Functions.

Make special note of the orientation of this spring, as it will fit in both directions; but only one way is correct.

 

post-246-0-80420000-1433857192_thumb.jpg

 

Without lubricating, install the Minute-counter Driving Wheel, 30min.

 

post-246-0-01981300-1433857195_thumb.jpg

 

Install the Lock, 2 Functions, and screw down (1.4 Driver)

 

post-246-0-40749100-1433857197_thumb.jpg

 

Before installing the next item, which is the Operating Lever, 2 Functions, be sure to lubricate the hinging point from underneath with D5.

 

post-246-0-57471800-1433857198_thumb.jpg

 

Then install the Operating Lever, 2 Functions.

Be sure that the spring arm of the Lock is out from under the Operating Lever and screw down (1.4 Driver).

Place D5 into the little slot opening in the top of the hinge point.

 

post-246-0-94725000-1433857200_thumb.jpg

 

Install the Chronograph Wheel Friction.

 

post-246-0-98261600-1433857218_thumb.jpg

 

Install the Ratchet Wheel Driving Wheel

 

post-246-0-73667100-1433857223_thumb.jpg

 

Before placing the Chronograph Bridge onto the movement, you need to oil the jewel circled in the image below with D5

 

post-246-0-23033600-1433857225_thumb.jpg

 

After oiling that jewel install the Chronograph Bridge.

 

post-246-0-59930800-1433857228_thumb.jpg

 

Next, place the Reduction Wheel into the hole in the Chronograph Bridge.

Note that there is no post to locate this wheel, as it's on Automatic Device Bridge which will be installed later.

 

post-246-0-93885800-1433857230_thumb.jpg

 

The next item is the Oscillating Pinion which seems to cause people a lot of frustration.

Here's my method to install it.

Firstly, be sure of the correct orientation, as shown below.

 

post-246-0-57699600-1433857232_thumb.jpg

 

Pull the Crown out to the third position to engage the Stop Lever and hack the movement.

Keep the movement in this hacked position until the Automatic Device Bridge is installed.

Then install the Oscillating Pinion and seat it into it's lower jewel. 

You'll know you've done this correctly when it sits up straight and centered in the slot ... as shown in the image below.

By taking your time and getting it well seated you will have less trouble when installing the Clutch later on.

 

post-246-0-87880700-1433857234_thumb.jpg

 

However, before we install the Clutch and Automatic Device Bridge, there are a few wheels and a hammer that need to be installed.

Install the Chronograph Wheel, 60s, 30min

 

post-246-0-43116400-1433857237_thumb.jpg

 

Install the Minute-counting Wheel, 30 min.

 

post-246-0-94035600-1433857239_thumb.jpg

 

Install the Clutch 60s, 2 Functions.

The Clutch needs to slip underneath a small click spring for the Reversing Wheel, so be careful not to bend and damage this spring.

Then gently lift the arm of the Clutch over the Oscillating Pinion. 

Yes, it's a delicate job, but with a steady hand, patience and well dressed tweezers, it's not too hard.

 

post-246-0-88769300-1433857242_thumb.jpg

 

Before we install the Reversing Wheel, we need to lubricate it.

The product needed is Lubeta V105, which is an immersion, or dip, lubricant.

 

post-246-0-76652300-1433857262_thumb.jpg

 

Simply hold the Reversing Wheel with tweezers and dip it into the solution.

Then allow it to dry, which takes about 10 minutes.

This leaves behind a waxy type lubricant that has impregnated deep into the wheel.

 

post-246-0-95009500-1433857264_thumb.jpg

 

Once dry, install the Reversing Wheel

 

post-246-0-36485100-1433857269_thumb.jpg

 

Install the Hammer, 2 Functions.

Make special note of the orientation of the cam to the hammer.

You may need to rotate the cam into this position before you fit the hammer.

 

post-246-0-06105300-1433857272_thumb.jpg

 

Now it's time to install the Automatic Device Bridge.

Make sure all wheel pivots are correctly located in their jewels before tightening down (1.4 Driver)

Pay close attention that the Oscillating Pinion is still seated correctly in it's pivot hole on the Clutch.

 

post-246-0-04474800-1433857276_thumb.jpg

 

One other troublesome operation for people is installing the Clutch Spring.

This is my method of installation.

 

Slide the long arm of the spring into it's position until the shorter end is touching the automatic bridge.

Then with your tweezers grab the point illustrated below and lift it over the locating screw.

 

post-246-0-78668700-1433857277_thumb.jpg

 

Once over the screw, push it forward and until the loop is seated on the locating screw.

 

post-246-0-86921400-1433857282_thumb.jpg

 

Lastly, install the Hammer Spring, 2 Functions.

 

post-246-0-81624500-1433857508_thumb.jpg

 

Now you can un-hack the movement by pushing the Crown into it's winding position.

Check that the Oscillating Pinion is being driven by the movement.

Check the Chronograph functions are engaging and dis-engaging correctly by operating the pushers.

 

Once you are satisfied all is well, turn the movement over.

 

 

post-246-0-38035200-1433857534.jpg

 

 

Now we come to the calendar work.

 

post-246-0-92086400-1433857538_thumb.jpg

 

For this I place the movement back in the Horotec 7750 plastic holder (MSA 09.050-01)

 

post-246-0-09824000-1433857537_thumb.jpg

 

Install the Free Cannon Pinion

 

post-246-0-37911900-1433857541_thumb.jpg

 

Install the Minute Wheel.

 

post-246-0-06093400-1433857544_thumb.jpg

 

Install the Hour Wheel

 

post-246-0-33142900-1433857546_thumb.jpg

 

Install the Intermediate Calendar Driving Wheel

 

post-246-0-91447600-1433857548_thumb.jpg

 

Next the Day Star Driving Wheel

It is most important that you line up the driving tooth of this wheel with the marker on the Main Plate.

If the wheel appears to be half a tooth off proper alignment, bring the Crown out to the hand setting position and adjust so the tooth lines up perfectly.

Failure to do this will result in improper synchronization of the day and date.

 

post-246-0-98391400-1433857550_thumb.jpg

 

Install the Date Indicator Driving Wheel.


This time you line up the wheel's driving tooth with the post for the Intermediate Calendar Driving Wheel.

Failure to do this will result in improper synchronization of the day and date.


 

post-246-0-22539300-1433857553_thumb.jpg

 

Install the Hour-counting Wheel

 

post-246-0-43423200-1433857555_thumb.jpg

 

Install the Hour Hammer

 

post-246-0-96122800-1433857577_thumb.jpg

 

Install the Hour Hammer Operating Lever

 

post-246-0-31808100-1433857581_thumb.jpg

 

Install the Hour Counter Lock

 

post-246-0-98896300-1433857584_thumb.jpg

 

Install the Hour Hammer Spring

 

post-246-0-14369300-1433857587_thumb.jpg

 

Place on the Date Platform, and secure down (1.2 Driver)

 

post-246-0-61413200-1433857590_thumb.jpg

 

Install the Double Corrector, making sure the spring is correctly positioned.

 

post-246-0-63688100-1433857592_thumb.jpg

 

Place on the Date Indicator.

 

post-246-0-04327200-1433857595_thumb.jpg

 

Install the Date Jumper.

Be sure you have selected the correct jumper, as the Day and Date Jumper are not Identical.

 

post-246-0-98747800-1433863811_thumb.jpg

post-246-0-39636400-1433857597_thumb.jpg

 

Install the Day Jumper

 

post-246-0-82588200-1433857599_thumb.jpg

 

Install the Jumper Spring.

 

post-246-0-25131900-1433857602_thumb.jpg

 

Place on the Date Indicator Maintaining Plate and screw down (0.8 Driver)

 

post-246-0-33783200-1433857624_thumb.jpg

 

Place on the Date Jumper Maintaining Plate and screw down (0.8 Driver)

 

post-246-0-92404200-1433857627_thumb.jpg

 

Fit the Day Indicator, and test the function and timing of the Day/Date

 

post-246-0-35807700-1433857630_thumb.jpg

 

Turn over the movement to fit the last item.

 

 

post-246-0-27017200-1433857631.jpg

 

 

The last item to fit is the Oscillating Weight.

Gently place it on the movement, check it's meshed properly and then screw down (1.5 Driver)

 

post-246-0-79642400-1433857633_thumb.jpg

 

Service on the ETA 7750 is now complete, and adjusting the timing of the movement is the only operation left.

 

I hope this has been of interest and helps those wishing to tackle this caliber.  I'm sure, as I did, that you'll find it a fun and reward movement to service.

 

 

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Astounding work and presentation Lawson. Having done a couple of small walkthroughs, I can really appreciate the time and effort that has gone into this. Thanks buddy!

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Hi Lawson,

 

I have no words to praise enough this excellent job and documentation! You have excelled yourself in this incredible work of love. Much appreciated your sharing and time put into it!

 

My friend, you ask about negative feedback, well I have one: you are too far from my house and I'd love to be your neighbour! :)

 

Cheers,

 

Bob

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      Here's a reference photo of the wheels.
       

       
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