On My Bench - Seiko 7A28-7039

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I have this on the bench to investigate an issue with the chrono seconds hand. It’s quite a nice watch, dating from 1983, and has held up well as the dial is in excellent condition and the case is well worn but still nice and sharp. Here’s a shot as it arrived.



After cleaning around the caseback with a pegwood stick and a brush, it’s removed to get a look at the movement.



All looks fine from a distance but inspection with a 4X loupe made me reach for the microscope. A closer view showed that the movement was in need of a service, there is dried oil on the jewels and the pivots in the bushings are lubricated with I don’t know what.

A couple of the jewels, one dried out,



one with "bits" on it.



Some of the bushings. This one has dried grease.


This one has dried out "something".



As does this one.



And this one has an extra little bit.



There is also a sliver of metal evident, not good in an electronic (or any) watch.



The pushers and tubes also have some gunk and rust, but that’s to be expected after so long being used as a tool and not a safe queen.

 
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So the hands are all now set to 12:00 and the battery removed so I can remove the stem, then the movement to access the dial and remove the hands and dial before starting on the movement. Stem removal.



All done and the movement out.



A shot of that nice dial.



Hands will will have to wait though, my current hand levers are too big for the chromo hands but new ones are on the way, so it’s all on hold until then.

 
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Last task before I finish the day with a beer.

Stripping the case. First, off comes the bezel.



Then the bezel seal, glass and glass seal and three pushers with springs and seals.



The back of the bezel will appreciate a good clean.............



as will the case.



So that's done for today, I'm going to enjoy a beer.
 
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....Stripping the case. First, off comes the bezel.....So that's done for today, I'm going to enjoy a beer.

and now folks, we know the true story of why it takes so long to get our watches back from service! 😜
 
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and now folks, we know the true story of why it takes so long to get our watches back from service! 😜

Working on this one today was interrupted by:

Problems with my computer.
The need to clean a down pipe in between downpours.
Time to find out where I left the ladder I need to get to the down pipes 😡.
Coffee time.
Getting the towels out of the dryer.
Thoughts that a beer would be nice.

😁
 
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Great post, thanks. How do you plan to clean all the gunk from the bezel, pushers and so on? Ultrasonic cleaner?
 
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Great post, thanks. How do you plan to clean all the gunk from the bezel, pushers and so on? Ultrasonic cleaner?

Cleaning parts like the bezel (where there is a delicate surface) is limited to a soft brush and cleaning solution and sharpened pegwood where crevices and little nooks and crannies need to be cleaned.

The case can be cleaned in the same way and then put in an ultrasonic for removing gunk and cleaning residue. That gives a good surface to inspect for corrosion and bad dings that may impair sealing.

The pushers can be done the same way.

The plates and wheels etc can be brushed and then I use a watch cleaning machine. That cleans off the gunk and I can inspect jewels etc and clean them with pegwood and then give them an ultrasonic to clean off any "cleaning" residue.
 
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Cleaned the bezel and case today.

Tools needed: Brass scraper, hard wooden stick, sharpened pegwood, toothpick, metal polish, power drill.



The case is first given an ultrasonic to remove the crud and then the brass scraper and sticks are used to remove the harder deposits.
This is the bezel being done, it didn't go in the ultrasonic, all hand cleaned.



After hand cleaning the case and using a drill with toothpick/metal polish to clean around the pusher and crown tubes, and a fine brush to do the inside of the tubes, it was back into the ultrasonic to clean of the polish and dust.



Nice clean crown and pusher tubes.



And a much cleaner bezel. Note the bezel removal notch at 11 o'clock. I wish more people would use them when removing these bezels instead of just going at it with an axe.



Finally, a nice clean case.

 
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Question for the gurus (@Archer, @Canuck, @ChrisN).

Is there anything I can use to treat the remaining rust spots that are visible in the pics above?
 
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Question for the gurus (@Archer, @Canuck, @ChrisN).

Is there anything I can use to treat the remaining rust spots that are visible in the pics above?

I would try to remove as much of it as possible. How you do this depends on what sort of depth there is to it, but it it's just surface rust, my secret weapon is an old typewriter eraser...one end in pink and the other white, and they are different hardness. I find these very effective for removing light surface rust from parts.

Alternately you could use some chemical product, but since this is presumably a stainless steel case, it' not likely needed.
 
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Thanks for the tips gents, I'll try the eraser, think I have one in my old drawing box. I haven't tried the fibreglass pens but I might order one and test it out.

Now, time to catch up.

My hand levers arrived, my watchmaker supplier hasn't got my preferred Horotecs in stock so I got a cheap set on eBay and they did the job without any issues.

Hands now removed and safely stored until they're needed.



The dial was quite easy to remove, only being held by two screws at the front. With them of it was easy to lift the dial off the movement with a stick and then it was placed in a dial case until re-assembly time. I noticed the absence of a dial washer (as per parts list) so I'll have to look through my parts box to find a suitable replacement.



Now I can start on the movement and once I get that stripped I can inspect the parts, clean them and start re-assembly.

But now it's time for a coffee.
 
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Well, with Ms JiO visiting her kin up in the hills, I had some quiet time to keep on with the movement.
After removing two cover plates The circuit block can be removed, I put it in a tin can so no UV light could affect the CMOS chip.
That done, I can see the four coil blocks, these are delicate so as soon as I remove the green circuit block spacer I'll take them out and put them in a seperate container.



With them safely in a plastic box, it's time to look at the train bridges.



These are a bit more complex than a standard mechanical watch, the wheels being so small, and the added delicacy of little magnetic step rotors. When impulsed by the coil/stator unit, they're the things that move the hand trains.

With the first bridge off I can remove the seconds wheel (the main chrono seconds counter). It looked a bit strange when I withdrew it so a quick look under the microscope showed the reason.

A huge amount of oil at the end of the shaft near where the second hand is fitted 😲.



The remaining bridges were done and no serious issues were found, just a severe lack of oil on most of the pivots and dried grease here and there.

We're now down to the bare main plate with just the four rotor stators to be removed.



All completely broken down now and ready for inspection / cleaning.



Enough for today, almost time for Ms JiO to get home and prepare dinner for me 😁.
 
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That microscope does an awesome job of showing just how much crud is locked in there.
 
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Just FYI - the rotors don't go in the cleaning machine, as they can be damaged pretty easily. Clean them off using pith wood and some solvent at the bench, and dry using a hand blower. The stators can go in, but you need to be sure they don't get bent in any way...you may find your watch running backwards of they do!

Do you have any quartz specific oil? I don't service quartz often, but I do keep quartz oil on hand - Moebius.

Cheers, Al
 
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Question for the gurus (@Archer, @Canuck, @ChrisN).

Is there anything I can use to treat the remaining rust spots that are visible in the pics above?

I use one of these to get rust spots similar off knives without leaving marks

 
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Try a fibreglass brush, before the pillar plate goes into the cleaner.
 
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Fascinating.
 
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Try a fibreglass brush, before the pillar plate goes into the cleaner.

Is this a watchmaker's tool? Where do you find those?

I find "Simple Green" bath cleans cases very well.