# 7A28 Service Hints?



## chucolo (Aug 25, 2014)

I am new to this forum--which, however, looks more promising for my inquiry than others.

So I'll ask my question and we'll see.

I just rediscovered my long lost Seiko 7A28, which I originally got in 1984.

To my delight, no visible damage in or out, and a new battery got it ticking straight away.

But the chrono now has what I take to be typical issues--the 2 right side pushers only sometimes function, and their hands (1/10 sec. and sweep second) don't zero out...both stop at random points each time.

Still, they sort of work, and all hands do 'tick' when things are just right. So, the main functions are there, just not reliably usable.

Now for the kicker. There is no watchmaker anywhere near. I know a little about watch repair, but still feel leery of dismantling such a nice piece for a full cleaning/oiling (which is doubtless what it really needs).

So...if anyone knows...what's the least "amount" of servicing I could try to restore full function?

I realize this is perhaps a foolish request...but there it is anyway.

Any tips or suggestions will be welcome.


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## Big Bad Boris (Dec 3, 2010)

Google "Seiko 7A28 manual", and you should find the instructions to make the sub dials reset to zero.

From memory, it's a simple process which involves pulling the crown out, and then depressing the various buttons to reset the counters back to zero.

The buttons intermittently working is probably due to years of crud being trapped under and around them. There will probably be tiny circlips inside the case holding the buttons in place (or the buttons may be held in place by the movement ring) . Remove the movement, then the circlips and buttons, and give them all a good clean.


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## kevkojak (May 14, 2009)

Get thee to the Seiko 7A38 forum and chat to the owner, Paul.

He used to be a member here but reacted quite badly to a change in forum software, so set up on his own! 

Anyway, he's the best around when it comes to info on the '28 and '38 movements and watches, what he doesn't know about them isn't worth knowing.


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## Sir Alan (Sep 10, 2010)

Here's one of mine, that was suffering from sticking sub-dial hands (9pm and 3pm).



If you are confident and competent, this is usually a simple fix.

First of all do a self test - press the 4pm pusher in and hold it. The 9pm, 3pm and main chrono seconds hand should all perform one full rotation.

If they do, or even if they judder or stick and then move it shows that the coils are working and the hands want to rotate. You may need to watch carefully for life here if a hand is sticking.

Next, drop the movement out of the case and very carefully nudge each of the above hands with a cocktail stick. This will free up any hand that might be stuck in one position.

Then try the self test again.

Next its time to look at the movement itself.

You need to remove the backplate and battery terminal, then very carefully remove the PCB to reveal this:



Be very careful not to damage the coils (avoid any contact) and also don't lose the rotary trimmer (the small gold finger on the left) - its best to take this off, but make sure you fit it back the correct way up.

There are four bridges on the 7Axx movement.

The first one (middle and on top) is the main chrono seconds hand). If you had a sticking or juddery hand this is where you'd look).

Removing it (and the sprung 'finger') reveals this:



If the problem was either the 9pm or 3pm sub-dial hand, then you need to remove the corresponding bridge (in both my photos they are the smaller bridges at either 12pm or 6pm).

I *strongly* advise against removing the main (centre) bridge as getting this back on is VERY tricky.

The other bridges are quite straight forward. This is what you'll see:



What I do is remove the green spacer block (its a push fit), remove the hand, remove the bridge and coil (for safety), clean the bridge, clean the gear wheels and rotor stator, then re-oil and re-assemble.

This is fiddly but the 7Axx are a real pleasure to work on as all the components are such high quality.


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## chucolo (Aug 25, 2014)

Kudos to Sir Alan!

I believe you've put me on the path to solutions, and I thank you heartily.

Given my old eyes and hands, I expect it'll take me a while to do what make look easy...but I'll give it a try.

However, if you don't mind....

My watch actually had little use before it went missing (bottom of a moving box), and had only had the back off for a single battery change.before then. I have to suspect the real culprit is just dried up lubricant...understandable at its age.

Is it plausible that simply dotting a bit of watch oil into the relevant pusher activating levers (2 and 4 o'clock points on movement side) could do the trick (plus cleaning the pushers in the case themselves)? All hands do work whenever I get positive action on those pushers.

Also...you advise removing, (early on) the "PCB", (and later) "the hand". Forgive obtuseness, but what's a PCB, and do you really mean the watch hand(s) on the dial side?

Obviously, I'm expressing nerves about disassembly damage...

Many thanks again for your time and knowledge.


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## Sir Alan (Sep 10, 2010)

Ah ......

I maybe assumed too much when I read this:

"both stop at random points each time."

If your problem is only the pushers (and not sticky sub-dial hands) then the fix is simple and doesn't need you to do any of what I suggested above.

You can reset each hand to its correct 12pm location by pulling the crown out one click and then push each of the three buttons to move each hand.

Do this to zero them, then perform a self test (push and hold the 4pm button).

If all three hands perform one full rotation and stop at 12pm position then all is good. (If they don't then see my post above).

If the pusher buttons are sticky and hard to activate, then there is most likely dirt under the button preventing full travel into the case to press the switch lever. The buttons need to be removed and cleaned and greased with silicone grease.

Here are some pushers (full of dirt)



and after they've been cleaned



and here is the case before cleaning (see the dirt in the pusher cups)



This is the PCB (circuit)


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## Big Bad Boris (Dec 3, 2010)

chucolo said:


> I have to suspect the real culprit is just dried up lubricant...understandable at its age.


Stick it on top of a radiator for 20 minutes and see if things improve. It's probably the wrong time of year to have your heating on - try heating the watch up with a hairdryer.


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## Big Bad Boris (Dec 3, 2010)

Big Bad Boris said:


> chucolo said:
> 
> 
> > I have to suspect the real culprit is just dried up lubricant...understandable at its age.
> ...


Err......... on second thoughts - Ignore the above !

It's a technique I've used on mechanical watches, but applying heat to a quartz is probably not a good idea !


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## chucolo (Aug 25, 2014)

Aha. Messages from all sources received.

I considered the heat trick and rejected it, for same reason.

I shall tackle the pusher job first...it's fussy enough, given the dinky c-clips. If that doesn't do the trick, then on to more adventurous waters. But I think I have the main picture(s) now.

Muchissimas gracias, Senores!

On a scarcely related subject...does any one of you have experience with or knowledge of a Seiko 8J41 movement (90's Seiko Dolce)? If so, I'd like to converse about it. It's a messy story--one I can't bring to a happy end on my own.

If not, I'll sign off with much gratitude for your generous help.


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## Big Bad Boris (Dec 3, 2010)

chucolo said:


> On a scarcely related subject...does any one of you have experience with or knowledge of a Seiko 8J41 movement (90's Seiko Dolce)? If so, I'd like to converse about it. It's a messy story--one I can't bring to a happy end on my own.


The Seiko Citizen watch forum (SCWF) would be your best bet.

You'll have to google it, as we are not allowed to post links to other forums.


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