Seiko 7A38 - by the numbers



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Forum Home > Parts Info, Tech Tips and Tinkering > Sticky: The all-too-common Displaced Finger Tension Spring chrono' sweep hand problem

Site Owner
Posts: 12808

And so it goes on - unabated. :roll:

Don't you just love it when an eBay seller posts a close-up of his cock-up. :lol:

This morning, a German eBay seller listed a 7A38-7240, with an over-optimistic 'pie-in-the-sky' Buy-it-Now price of 299 Euros. It's in average worn condition, but unusually (for this model) still fitted with its correct original two-tone bracelet.

Seiko 7A38-7240 Chronograph Day Date 80er Rarität Quartz Top Zust. Originalband

The English language part of the seller's description includes the following:



Movement is in working order and keeps good time.

All Funktions are working properly!

You´ll buy what you see at the pictures.

May 24, 2019 at 7:38 AM Flag Quote & Reply

Posts: 9
Can the spring also be displaced vertically?
August 31, 2019 at 5:14 PM Flag Quote & Reply

Site Owner
Posts: 12808

I wouldn't describe yours as 'displaced vertically' - more like bent upwards, Hanson.

With the more common lateral displacement, you can sometimes just flick the finger tension spring back into place with the point of a cocktail stick. Though I find it pays to loosen the retaining screw, to re-position it perfectly central over the jewel / axle. But you will need to remove yours and carefully bend / twist it back into shape - with the emphasis on carefully. It's very thin stainless spring steel. You really only get one chance. If you try re-bending it a second time they usually snap.

PS - You may already have noticed, but your Alien's movement is also missing the rotary step switch.

September 1, 2019 at 1:10 AM Flag Quote & Reply

Posts: 9

Hmm.. I may leave it for my watchmaker then.

Nope didn't realise that! Thanks Paul =P

This Aliens project watch is finding new ways to make me realise that I didn't get the bargain I thought I did haha..

The NOS crown I just received from eBay has a broken off stem inside, although listed as New. Seiko Oceania have the steel crown 45M60NS1 in stock which I might see if they actually have, and then get it powder coated black...

September 2, 2019 at 12:22 AM Flag Quote & Reply

Site Owner
Posts: 12808

Here's another example of this classic self-inflicted cock-up, by someone who really ought to know better. :roll: Yesterday evening, Italian eBay seller 18hobbyman13, who regularly dabbles in Seiko 7A38's (and has been known to mess about with the occasional FRED Force 10) listed a 7A38-7240 in average worn condition - twice:

Firstly as a 7-day auction, with an opening bid price of 1 cent (0.01 Euros).

Again, in parallel, as a Buy-it-Now for an absolutely ludicrous 333.33 Euros. :lol:

Check out his last photo in both listings:

His two indentical descriptions both include the same phrase:

.... come funzionante completamente e perfettamente.

Which translates as: as working completely and perfectly.

I really don't see how, Daniel. :P

October 13, 2019 at 5:04 AM Flag Quote & Reply

Posts: 4

Just received mine and the same thing. I saw it couldn't be right so googled some open caseback images, spring was to the side like the pic above.. 

The Renata battery also weeping slightly with signs of moisture. a few drops and a small amount of green. :(

Got a Seiko battery on the way tho apparantly Eveready and Sony are rated better?

October 17, 2019 at 12:35 PM Flag Quote & Reply

Site Owner
Posts: 12808

Given that most instances I see of this classic self-inflicted fault are in eBay listings, it makes a refreshing change to see an eBay seller who has actually bothered to read this thread, even if he didn't understand the ramifications. This partly functional well-worn 7A38-7240 was listed overnight by a US eBay seller as a 5-day auction (albeit with an over-optimistic opening bid price of $139.95):

Fresh from an Estate Sale, you are bidding on a Very Desirable Vintage 1987 Men's Seiko 7A38 Chronograph with Day/Date Calendar that started to Run when a New Battery was Installed, however, it has some issues. I am not a watch repairperson, just Battery Changer, but I did some research and it may be related to the Friction Installed Cannon Pinion, that may have loosened up. So, when the Minute, Hour and Sub Minute hand do not function (meaning gain time, when all the other hands are rotating), it may be the Cannon Pinion is slipping. Just to mention something else I found on a Seiko 7A38 online blog. If you notice in the pictures of the movement, you see a little arm in the center that covers a jewel, where I guess on the other side is the Cannon Pinion. If I read it correctly, in the blogs, it says that the spring/tension cover needs to actually cover that jewel. That's why the hands won't rotate, so I did move it over to cover it and still nothing happened. I am still leaning toward the slipping pinion. Anyway, I leave it to you to figure out.

November 7, 2019 at 6:58 AM Flag Quote & Reply

Site Owner
Posts: 12808

The Kamatz 519000 'Tango Charlie', which I'd bought off eBay in the States last week, and which was delivered this morning, arrived with a distinctly recalcitrant sweep second hand. I'd expected it. The seller had written in the item specifics:


No guesses as to the culprit - yet another deftly deflected finger tension spring. :roll:

I slackened off the retaining screw a turn and flicked it back into place ....

That isn't quite as bad as it might appear. It's not a groove worn in the end of the finger tension spring, but a build-up of dirt, filings and old oil. But just to be sure the end of the axle was still intact, I removed it completely to check underneath. ;)

November 30, 2019 at 8:50 AM Flag Quote & Reply

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