Seiko 7S26A Complete Service Walkthrough

[bobm12]

Geo is right, I thought you were talking about the plastic gears in this movement.

[Don]

Actually I meant both the plastic gears and the calendar wheel. Thanks for the answers guys.

[bobm12]

Hi Lawson,

 

I know this is an old post...although I'd say it will never become old due to being a great tutorial.

 

This Bergeon arbor barrel holder comes in several sizes. Which is the one pictured, the 2 mm? Would you say it is the most useful? What sizes are most recommended, do you know? Thanks in advance, I'm trying to start my "arbor barrel holder collection" :)

 

Cheers,

 

Bob

[Lawson]

bobm12, on 26 Jan 2015 - 05:17 AM, said:

Hi Lawson,

 

I know this is an old post...although I'd say it will never become old due to being a great tutorial.

 

This Bergeon arbor barrel holder comes in several sizes. Which is the one pictured, the 2 mm? Would you say it is the most useful? What sizes are most recommended, do you know? Thanks in advance, I'm trying to start my "arbor barrel holder collection" :)

 

Cheers,

 

Bob

 

Hey Bob my dear friend :)

 

I only purchased the arbor holder for use with my KIF tools; I haven't used it for it's intended purpose ... never found the need to.  Also this is the only size I own.

I would maybe come in handy to easily turn the arbor on older models to secure and test that it's grabbed onto the mainspring, but other than that I'm not sure.

 

BTW - I find that I use that plastic coated paperclip more on KIF spring then the special A*F Tools, the way it forms around the KIF spring and holds it can't be beaten IMHO.

[bobm12]

That's good to know since they are about US50+ a pop! Bergeon makes them in many sizes so I suppose I will buy my first one when I need it.

 

The paperclip trick is excellent although I tend to lose them "tools". Sometimes out of laziness (I have every tool), I simply use 2 tweezers, especially for this movement. I learned the trick from our Mark here. Disengage the spring with a screwdriver and engage it back with the tweezers. One to hold and the other to turn the spring! Oh, well, sometimes I wonder why I bought all the stuff if I do all the shortcuts!

 

Cheers, mate and thanks for the sharing!

 

Bob

[Vich]

Thanks for the walkthrough Lawson it will be really essential reference material for me when I start to sort out my Indian Seiko.

 

Cheers,

 

Vic

[xzqt]

Excellent guide sir.

Useful.

[Gary]

Hey Lawson,

I am about to start on a Seiko 7019 and wanted to see if you could share with me if there is a screw holding the movement in the case? First Seiko I've worked on so I'm at a loss and a little intimidated.

Any guidance would be appreciated.

[Lawson]

Hi Gary,

 

To the best of my knowledge I don't think so, but with so many variations in case design it's hard to be 100%.

Once you have removed the stem from the movement, if is doesn't easily come out of the case, just post of photo and we can look at it together.  Don't force anything, as that only leads to issues.

 

Don't be intimidated either mate, Seiko movements are fun and friendly to work on.  Just take your time, and take HEAPS of reference photos of things you feel are important for reassembly.

 

Let us all know how you go with your service too :)

[SCOTTY]

Assembly

 

This is a very easy watch to re-assemble.  In fact I'd recommend the 7S26A to be the first Japanese Movement to practice on, because it's so beautifully and logically laid out.  The only downside to this watch is that you have to buy one special tool from Seiko, the S-921 Philipshead Screwdriver; but it's not very expensive and once you've got it, you have it for life.

 

Seiko-24.jpg

 

For oiling information and a parts list for your movement, please download the copy of the Tech Guide below:

7S26A_7S36A.pdf

 

Drop in the Clutch and Intermediate Wheel.

Then push the Stem into the shaft.

 

Seiko-26.jpg

 

Fit the Centre Wheel, and attach the Bridge.

Then drop in the Mainspring Barrel, and refit the Click.

 

Seiko-25.jpg

 

Refit the Keyless Work, and I have to say the Seiko design is a HUGE improvement over the AS and ST Keyless Work design ... no fiddly Setting Lever screw to worry about ... Love it!!

Once the Keyless Work is installed, install the Third Wheel, then the Fourth Wheel, and lastly the Escape Wheel.

 

Seiko-27.jpg

 

Next, fit the Barrel/Train Wheel Bridge.

PLEASE NOTE: Be careful to check that you have pulled the Click out from underneath the bridge BEFORE you begin locating the pivots of the train.

 

Seiko-36.jpg

 

Once all the pivots on the train are in place, and you're happy it's all moving freely, use the three longest screws to secure it down.

 

Seiko-35.jpg

 

Install the Ratchet Wheel, and the Second Reduction Wheel.

Two things to note here:

Firstly, when screwing down the Ratchet Wheel, make sure to clear the leg of the Pawl Lever, as it has a nasty habit of wanting to slip under the screw.

Secondly, as you screw down the Second Reduction Wheel (Reverse thread remember!), keep adjusting the Pawl Lever arms so they rest on either side of the wheel.

 

Seiko-28.jpg

 

Next, fit the Pallet and Pallet Cock, and then the Balance.

 

Seiko-29.jpg

 

This particular movement has the DiaShock system for the IncaBloc. 

 

DiaShock.png

 

To remove and refit these for oiling I suggest you make a simple tool from a plastic covered Paperclip.

Straighten out the Paperclip and cut it to a comfortable length to work with in your fingers.  Then pull the plastic cover down about 4-5mm ... as pictured below:

 

Use this like you would Pegwood, over the top of the DiaShock Spring, as you use your tweezers to turn the spring and remove/refit it.  The plastic cover will conform to the shape of the spring and hold it securely without damaging it ... It's works a treat!

PS. Sorry I couldn't get a photo of me removing/refitting the spring with this little tool; but I don't have someone here to do the camera work, and only have two arms.

 

Seiko-37.jpg

Seiko-38.jpg

 

Next, flip the movement over, and reinstall the plastic Location Ring.

 

Seiko-30.jpg

 

Install the Cannon Pinion, the black plastic Date Driving Wheel, then the Motion Work, and lastly the Calendar Ring.

 

Seiko-31.jpg

 

Install the Date Jumper Plate

Install the white plastic Date-date Corrector Wheel and it's Intermediate Wheel

Note: Remember from disassembly that the black plastic Date Driving Wheel needs to lip over this plate.

 

Seiko-32.jpg

 

Install the Date Dial Guard

 

Seiko-33.jpg

 

Place the Day Disk on the shaft and push the Circlip down the shaft after that and push down until it locates in the Circlip Groove.

 

Seiko-34.jpg

 

Lastly, reinstall the Oscillating Weight, Dial, and Hands.

Case back up and your done!

 

Seiko-39.jpg

 

I really enjoyed working on this movement, and I thank my Heavenly Father for the skills and ability to be able to do this type of work ... amen!

I tried this with a 7s36C & its running way too fast, well beyond adjustment of the hairspring, which is in good shape & demagnetized. Please help !  Thank You!

[Blacklab]

Scotty, make sure the hairspring is thoroughly degreased, I normally pour fresh lighter fluid over the complete balance prior to reassembly.

[SCOTTY]

Scotty, make sure the hairspring is thoroughly degreased, I normally pour fresh lighter fluid over the complete balance prior to reassembly.

Thanks! Should I soak the assembly also ?  Btw, It's almost a new movement. I'm trying to learn but I left the balance assembly intact.

[Blacklab]

You can do it while its connected to the balance cock, but you will need to dismantle & re-lube the diashock after. Its better to remove the balance from the balance cock. Do you use a Timegrapher?

[SCOTTY]

You can do it while its connected to the balance cock, but you will need to dismantle & re-lube the diashock after. Its better to remove the balance from the balance cock. Do you use a Timegrapher?

I didn't use or have one but if it didn't slow down any in the entire range of adjustment I didn't think that would be the issue.

[Blacklab]

Have a look at the Guv's videos:http://www.watchrepairtalk.com/page/watch_repair_videos.html/_/balance-escapement-videos/watch-fault-finding-the-watch-is-gaining-r21 & https://www.youtube.com/watch?v=zQKoksLz12g&index=1&list=PLwP8fNxqhOvPoUINDYdiN_xp4y1l4ry1Q

Might be worth asking the old fat beardy bloke in the red suit for a Timegrapher.

[SCOTTY]

Have a look at the Guv's videos:http://www.watchrepairtalk.com/page/watch_repair_videos.html/_/balance-escapement-videos/watch-fault-finding-the-watch-is-gaining-r21 & https://www.youtube.com/watch?v=zQKoksLz12g&index=1&list=PLwP8fNxqhOvPoUINDYdiN_xp4y1l4ry1Q

Might be worth asking the old fat beardy bloke in the red suit for a Timegrapher.

Blacklab,  Thank you for the links. I can't get to it yet but I'll keep you posted. Thanks again !   

 

 

 

                                                                                                                                          PS: Maybe St. Nick will come through too.

[jdm]

After much procrastination I've completed my first service with one these these yesterday, and did another one today. I deviated a little from the usual cleaning process as I cleaned only the parts carrying friction and left screws and all unmovable parts alone, together with plastic one of course. I did that to minimize the chance of losing something. I use isoprophilic alchool only in a cheap ultrasonic household cleaner. For lubrication I use 9010, 9104 and 8301. I've also replaced a MS using GR2377X. I did not even attempted opening the small diashocks, as the balance ones already give ample opportunity for losing part or screwing up.

 

Except a couple stupid mishaps all went well and it was a lot of fun, but coming to practical results the first movement showed poor amplitude, around 135 deg and a very irregual beating. I swapped barrel, palled fork and balance from another and things improved, however it is very poor across positions and it stops something. It must be said that these are very old 7S26A movements. Since I got more problems with its dodgy case and broke a stem because of that, I put that one aside, having it accomplished its training purpose.

 

The other movements went better, a more recent B version but I knew since the beginning it had a distorted HS, which I tried to correct with very dubious results. Manipulating the HS is extremely difficult. This other one showed better amplitude, around 180 deg but as as soon I changed position it began running horribly. I swapped again balance from an A movement and it started running acceptably. I will check it again tomorrow for reliability and power reserve.

 

I may have over-oiled it or the escapement could have issues, is kind of deluding to face hard issues like poor amplitude and large rate variation across positions that require much better skills than mine.

Edited November 29, 2015 by jdm

[bobm12]

Hi jdm, I believe the problem is mainly on pivots and that you didn't clean the diashock jewels. Also, the rest of the jewels need to be immaculate. I usually use a pegwood stick whittled down so the tip can go through the jewel holes and peg them well.

 

I don't know about alcohol -- it may even leave an undesirable residue -- but you will probably have better results with lighter fluid.

 

Excess lubrication can be a problem too...it is said you must oil a whole watch with one drop of oil. In any case, I see you are going the right way with you experiences.

 

I wish you much success and please, take some pictures for us.

 

Cheers,

 

Bob

[clockboy]

After much procrastination I've completed my first service with one these these yesterday, and did another one today. I deviated a little from the usual cleaning process as I cleaned only the parts carrying friction and left screws and all unmovable parts alone, together with plastic one of course. I did that to minimize the chance of losing something. I use isoprophilic alchool only in a cheap ultrasonic household cleaner. For lubrication I use 9010, 9104 and 8301. I've also replaced a MS using GR2377X. I did not even attempted opening the small diashocks, as the balance ones already give ample opportunity for losing part or screwing up.

 

Except a couple stupid mishaps all went well and it was a lot of fun, but coming to practical results the first movement showed poor amplitude, around 135 deg and a very irregual beating. I swapped barrel, palled fork and balance from another and things improved, however it is very poor across positions and it stops something. It must be said that these are very old 7S26A movements. Since I got more problems with its dodgy case and broke a stem because of that, I put that one aside, having it accomplished its training purpose.

 

The other movements went better, a more recent B version but I knew since the beginning it had a distorted HS, which I tried to correct with very dubious results. Manipulating the HS is extremely difficult. This other one showed better amplitude, around 180 deg but as as soon I changed position it began running horribly. I swapped again balance from an A movement and it started running acceptably. I will check it again tomorrow for reliability and power reserve.

 

I may have over-oiled it or the escapement could have issues, is kind of deluding to face hard issues like poor amplitude and large rate variation across positions that require much better skills than mine.

Unfortunately jdm as you have found there are very few shortcuts with watch repair/servicing. All jewels need to be spotless the upper & lower jewels of the balance being very much the case. Having said that I have found Seiko,s never seem to have a high amplitude but should be above 200.

[jdm]

Thanks. To my dismay this morning I've found the movement has stopped.

 

The be fair i did all that pegging the holes etc. I've inspected all jewel holes under high magnification and all are spotless. If I give the smallest push to the train it spins freely for a long time. The alcohol I've used is the pure white one same as the professional rinse solutions, it doesn't leave any residue. I think I've used much less than a drop of oil in total, but I may redo the balance jewels, that aren't too difficult after all.

 

I think one has to be reasonable about the material at hand, can't expect miracles, none of these was bought as working movement.
 

Edited November 29, 2015 by jdm

[clockboy]

Thanks. To be fair i did all that pegging the holes etc. I3've inspected all jewel holes under high magnification and all are spotless. If I give the smallest push to the train it spins freely for a long time. The alcohol I've used is the pure white one same as the professional rinse solutions, it doesn't leave any residue. I think I've used much less than a drop of oil in total, but I may redo the balance jewels, that aren't too difficult after all.

I think one has to be reasonable about the material at hand, can't expect miracles.

Inviato dal mio GT-I9190 utilizzando Tapatalk

Ok if everything is clean & the hairspring is good it could be just out of beat. Poor running in different positions is normally a end/side shake issue with the balance or escape.

[jdm]

Ok if everything is clean & the hairspring is good it could be just out of beat. Poor running in different positions is normally a end/side shake issue with the balance or escape.

 

Thanks. I had regulated beat error at 0 yesterday. Now it show a little more.

[clockboy]

Thanks. I had regulated beat error at 0 yesterday. Now it show a little more.

0 or near will not make the difference you are looking for.

[jdm]

0 or near will not make the difference you are looking for.

 

Yes understand that and in fact I did not mention beat error as a possible reason. 

To not further hijack this thread I may continue in another one.

[clockboy]

Yes understand that and in fact I did not mention beat error as a possible reason. 

To not further hijack this thread I may continue in another one.

OK just looked at the timeograph reading and not much amiss wondering if it,s just the mainspring is not winding fully.