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Craftsman
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724 Posts
Discussion Starter · #1 ·
One of my favourite watches is this one, the SEIKO 9F62-0AB0 GS quartz.



I bought it 2nd hand for a very good price a few years ago and absolutely love it. The dial and hands are sublime and while the case has got quite a few nicks, dings and scratches (none of my making) I have lived with it as-is. I went to wear it a couple of weeks ago and found it stopped, so I assumed it must be a dead battery and put a new one in and the watch started ticking with that precise, bang on the dial tick marks that I love.

A few days ago I decided to wear it again, so popped it on the wrist, went out, came back and to my horror found that it had stopped several hours previously. Much discouraged I set the time and the watch started to tick again. So I left it, and some time later I returned to find the seconds hand pulsing, but not making it to the next mark. OK, so there is clearly a problem .........

Time to see what is going on inside.



the first thing that was apparent was that this movement comes out from the front, a bit of a pain as it meant I'd have to remove the bezel.

Having done this I removed the hands, trying as best I could not to inflict any damage to them or the dial



here are the hands with their zaratsu polishing



next I removed the case clamps and with the crown/stem removed the movement came out



next I removed the dial - by turning the two dial feet clamps and then gently lifting the dial away. I found the dial to be quite resistant to being lifted, the reason being the plastic dial ring and the nature of the holes through which the dial feet pass



the holes are square rather than round and the dial feet are an interference fit



dial code 32 - caseback serial number 29xxxx. So, the watch is coming up to 10 years old.

This left me with just the movement to strip down and hopefully find the cause of the problem.



What a gorgeous movement :)

My experience with quartz movements led me to suspect that there must be something obstructing the gear train - starting at the magnetic rotor (maybe a tiny piece of metal or even rust?), then moving through the train of gears (maybe a fibre, or a dust / dirt particle jamming one of the teeth?).

First I lifted the bridge holding the circuit in place





then the main bridge



to reveal the gear train



lifting the wheels out, and inspecting each revealed nothing?



so deeper into the movement we go





The small spring assembly is designed to remove any/all backlash from the hand as it pulses, ensuring it hits each mark perfectly - every time.

I think at this point I might / should have spotted the issue, but I was still focussing my thoughts on the rotor so moved swiftly on with the disassembly





this revealed the keyless works and gave me access to the rotor, stator and coil. At this point I'd not found the problem, but having gone this far I decided to continue with the dial side so that I would have full access to the jewel pivots for the train gear and could ensure there was nothing obstructing them.



the calendar plate (or dial guard) is held in place by three tiny Phillips screws (I think these are the same as the one found on the 7S26 and other 'modern' movements).

By the law of Sod, two of these came undone easily (I use an orange 0.5mm flat blade screwdriver) - but one of them would not budge. So I had to modify a thicker blade (I think I used the yellow 0.7mm blade) with my dremmel so that it was a perfect fit



success



having completed disassembly and cleaning, and still not having found a problem (grrrrrr) I started the rebuild, hoping that some magic may have happened and the issue would have gone away (yep - the age old prayer of tinkerers the world over).

tbc
 

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Craftsman
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724 Posts
Discussion Starter · #2 ·
Luckily having got to this point of the rebuild



I found the problem.........



dried, congealed and very sticky oil, which after cleaning looked like this



that shaft is part of this bridge



and the cannon pinion (?) that you can see fits over it and should spin freely on it (driving the M hand).

The sticky oil was significantly impeding this rotation - I guess enough to stop the movement. Once I'd separated and cleaned them I was able to continue with the rebuild









prior to fitting the circuit and bridge, the small rotary switch is placed - this is the same design as used in the 7Axx movements (which I know so well) and allows the movement to be regulated if required.







with the battery fitted, and life detected it was then over to the dial side







and then back on with the dial



and with the S hand lightly fitted I left the movement to run for 24 hours feeling confident that all would be well now .......
 

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Craftsman
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724 Posts
Discussion Starter · #5 ·
I was pleased/relieved/thankful that a day later the movement was still ticking nicely. Time for the scary bit .... attaching these



which went well.



and then the seconds hand



phew. Heart can now return to chest.

Given I had the case apart and I had been conscious since it arrived that it had too many scratches for my liking





I decided to have a go at some basic polishing. The objective being to not make it worse, and ideally improve things.

The sides are highly polished, but the upper surface has a very fine grain which for now I decided to leave alone. So, out with the kapton tape





and into the workshop where I have a small polishing wheel and some polishing compounds. Of course I had to look up which was which ....



I started with grey, then onto green



and I was happy with the results



I also did the bezel as this had several annoying scratches



then it was back inside and a thorough cleaning of the case components and then an even more thorough drying.

All ready to get back together



and the finished result





definitely an improvement, both cosmetically and functionally!!!

And on the wrist this afternoon



We have had another very hot summer here in the UK and I wonder if these temperatures (high 30's) might have been the cause of the oil drying out they way that it did??
 

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Craftsman
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2,417 Posts
Beautiful work Simon. I have a question related to a servicing quartz movements. I typically use something like 9501 on the cannon pinion and center wheel. Due to its viscosity and thickness, would you recommend a lighter oil or grease for these quartz movement cannon pinions ie. HP1300/Moebius 9405 or something lighter? Could using something like 9501 cause stoppage?
 

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Craftsman
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724 Posts
Discussion Starter · #15 ·
Beautiful work Simon. I have a question related to a servicing quartz movements. I typically use something like 9501 on the cannon pinion and center wheel. Due to its viscosity and thickness, would you recommend a lighter oil or grease for these quartz movement cannon pinions ie. HP1300/Moebius 9405 or something lighter? Could using something like 9501 cause stoppage?
I'm currently using 9501 - only time will tell how this (and the other lubricants I'm using) perform after 5+ years.

As you know, most of the watches we work on come to us either never having been serviced (typically quartz watches, but many of the vintages ones as well), serviced 20+ years ago, or badly 'serviced' with either the wrong or too much lubricants.

We therefore don't have a good reference to work against - i.e. a watch that was correctly serviced say 5 years ago - to see how the lubricants change over time.

I have serviced a few of my modern SEIKOS's - the Spork (4R15A), the MM300 (8L35A) and now this 9F62A and in all cases found dried and or congealed lubricants which were significantly affecting performance.
 

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Craftsman
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2,417 Posts
I'm currently using 9501 - only time will tell how this (and the other lubricants I'm using) perform after 5+ years.

As you know, most of the watches we work on come to us either never having been serviced (typically quartz watches, but many of the vintages ones as well), serviced 20+ years ago, or badly 'serviced' with either the wrong or too much lubricants.

We therefore don't have a good reference to work against - i.e. a watch that was correctly serviced say 5 years ago - to see how the lubricants change over time.

I have serviced a few of my modern SEIKOS's - the Spork (4R15A), the MM300 (8L35A) and now this 9F62A and in all cases found dried and or congealed lubricants which were significantly affecting performance.
Thanks Simon. Good to know. I think a lot of the modern watch oils and greases in the 9000 series are synthetic based. Advantage is longer life but disadvantage is they evaporate. The older lubricants best I can tell are plant or animal based and those are the ones that congeal or turn into a sticky mess resulting in stoppages. I guess there is good and bad to both.

The 7548 quartz I serviced recently was stopping at date changeover. I was really at a loss. Your thread got me thinking about the center wheel and cannon pinion. It would run perfect right up to the point the date wheel tooth would ramp up onto the date advance spring. After spending hours inspecting parts and looking at things under the microscope and adjusting or chaining lubrication on the train and calendar side, I found the issue is the wear to the center wheel port in the main plate causing excessive back and forth movement of the center stack and gear lash under load that would either bind or cause the gears not to mesh properly to keep the train moving forward resulting in the second hand just bouncing in place. Now I need to up jewel the center wheel port in the main plate with a 6309 center wheel jewel to resolve the issue. I will try and post something when I get into it and effect the repair.
 

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The 7548 quartz I serviced recently was stopping at date changeover. I was really at a loss. Your thread got me thinking about the center wheel and cannon pinion. It would run perfect right up to the point the date wheel tooth would ramp up onto the date advance spring. After spending hours inspecting parts and looking at things under the microscope and adjusting or chaining lubrication on the train and calendar side, I found the issue is the wear to the center wheel port in the main plate causing excessive back and forth movement of the center stack and gear lash under load that would either bind or cause the gears not to mesh properly to keep the train moving forward resulting in the second hand just bouncing in place. Now I need to up jewel the center wheel port in the main plate with a 6309 center wheel jewel to resolve the issue. I will try and post something when I get into it and effect the repair.
The only rotational torque on the center wheel in a 7548 comes from the magnetic stepping motor- very small indeed. Which is why I can’t figure out how the mainplate hole would become worn enough through running to cause a meshing/alignment issue. Are you sure it wasn’t shrinkage of the plastic date driving wheel and day finger on their posts that was causing increased friction? That is much more common in my experience of the 754x caliber, along with damaged teeth on the plastic intermediate date driving wheel.
 

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Craftsman
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2,417 Posts
The only rotational torque on the center wheel in a 7548 comes from the magnetic stepping motor- very small indeed. Which is why I can’t figure out how the mainplate hole would become worn enough through running to cause a meshing/alignment issue. Are you sure it wasn’t shrinkage of the plastic date driving wheel and day finger on their posts that was causing increased friction? That is much more common in my experience of the 754x caliber, along with damaged teeth on the plastic intermediate date driving wheel.
I looked at it all Noah. Intermediate date gear, date change gear, date wheel teeth, etc. Swapped in an intermediate date gear from a 6309 because my original looked bit suspect although the gears all worked by hand. Plastic gears all rotate freely by themselves on the plate with minimal effort and teeth are undamaged. All viewed under 30x scope. I am not sure of the cause of the issue but it has been documented long before my arrival that the center wheel port on 7548s are prone to oval wear. This shows up as the cannon pinion and hour wheel stack movement side to side in the main plate. In my case, it was enough to result in binding or stoppage of the movement. I could look at the train advancement through the port in the calendar side of the main plate and see the moment halt and bounce as the movement was put under load with the date finger and date wheel teeth on the jumper spring ramp. Apply a bit of side pressure with my tweezers on the stack one way and the train starts again and pushes just fine under load. Let off the pressure on the center stack or push a bit in the opposite direction and the train binds or stops. Once I fit the center wheel jewel, I guess we shall see if my diagnosis was correct.

Not to take anything away from Simon and his work here. Just fantastic. Reading about his issue with the center wheel and lubrication lead me to check the center wheel and cannon pinion lubrication on my own watch and discovery of the issue. I will post in a separate thread once I initiate the repair.
 

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Very nice step through and a beautiful watch...may have changed my mind about GS Quartz.

I am in the market for something with GS on it...just not sure which direction to head in quite yet.

Thank you, as always, for sharing.

JR
 

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Not to take anything away from Simon and his work here. Just fantastic. Reading about his issue with the center wheel and lubrication lead me to check the center wheel and cannon pinion lubrication on my own watch and discovery of the issue. I will post in a separate thread once I initiate the repair.
Certainly don't mean to deflect from Simon's post, but it highlights an important thing about the 754x problem- it doesn't take much (crystallized oil in the case of the 9F) to stop a quartz stepping motor from operating properly. So the idea that this same relatively low-torque motor could dig a rut into a large brass center hole is a hard one for me to wrap my head around. I'm going to have to ponder this further.
 
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