Seiko 7T04A

[seikoenthusiast]

Hello

I have this Seiko 7T04A movement that needs to be replaced. It has been dropped in water that has penetrated the case.

I have a few questions - I know it is a bit risky to talk about non-seiko replacement movements in a seiko group - but I'm risking it anyway

1. Can a YM04A be used as a replacement, if yes, what is the difference, or is there a cheaper and just as good alternative?

2. The crown stem is bended, so I will need a new and probably also a new o-ring. Where to get one that fits the YM04A movement?

3. One of the small hands are missing. Where to get a new one?

I am not a registered business, so I am not able to deal with the big retailers. Only a hobbyist.

Hope you can help!

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[Seiko7A38]

I am not familiar with the Seiko 7T04A movement per se. That said, many older Seiko 7Txx movements, like the 7T27 and 7T32 have multiple equivalents from the likes of S.Epson (Seiko Epson), Shiojiri, Orient Watch Co. etc. Check out https://calibercorner.com/s-epson-caliber-ym04a/ and you'll find it looks identical, so I'd assume is 100% compatible.

NOS replacement movements are available on eBay from a German seller: https://www.ebay.co.uk/itm/186504728945
The S.Epson YM04A equivalent from a Cypriot seller is somewhat cheaper: https://www.ebay.co.uk/itm/396881613446
Note however, both these movements have black numbering on white background date wheels.

I'm not sure what you mean by the crown / stem being 'bended'. They are threaded together. You'll need to withdraw the stem to remove the old movement. Suggest you re-use the old one unless it's badly rusted. A new stem will need to be cut to the correct length. Similarly re-use the old plastic movement ring. Be careful removing it; it may be brittle.

No idea where you could obtain the missing sub-dial hand without knowing the full 7T04-xxxx case-back number. Hmm.
I'm guessing that your watch is a 7T04-0AT0 (SPC235P1).

7T04-0At0-SPC235P1.jpg (60.47 KiB) Viewed 1584 times

If that's correct, then the Seiko part number for a sub-dial hand (all three are the same length, surprisingly given the different diameter sub-dials) is 3BA035F4BAW. It's a fairly commonly used hand, also found on 7T62's 7T92's 7T94's etc.
Cousins UK have them in stock under their part number S61409. Cousins will deal with individuals direct.

CousinsUK-Seiko-3BA035F4BAW.png (77.39 KiB) Viewed 1571 times

Otherwise you could use any similar appearing hand with a 0.21mm hole.

[Seiko7A38]

In case you need any more parts, like a new crown or crystal, here's the full parts list from Seiko Oceania's database:

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7T04-0AT0-PartsList-2.png (16.97 KiB) Viewed 1574 times

[seikoenthusiast]

Hi Paul

Thanks a lot for your quick reply and for all the research you have done already!

If you don't see any difference in specs for the YM04A (other than the color of the date plate), and I see the same, then I guess I am good going with the YM04A

Thanks for researching the links!
I also found it on Aliexpress a little cheaper, but it has no stem that come with it: https://www.aliexpress.com/item/1005008253433926.html
Would you know where to get a stem and O-ring seal that fits the YM04A movement?
(With the parts number from the Seiko database I can find one listing, which is from the US an would end up being quite expensive: https://www.ebay.co.uk/itm/135072306470 - do you know of other options? Or what to search for?)

The current stem is not useable, i.e. it has a bend to it, so it is not completely straight anymore and has troubles turning. I attach a picture.
Or do you see any possibility in restoring it?

It really looks like it is the SPC235P1 - I am amazed you could recognize it just so
You mention that we would need the caseback number. I have included a picture, does that bring us closer?

Regarding the hand, google returns almost no results searching for the parts number, and ebay returns zero.
Buying from the UK would result in very high additional tax costs since they are not part of the EU, so that is not a possibility.
Would you know other hands that look like them, but are easily available and common? Or what search terms could I use to find one? I can live with a little difference, that even adds a personal touch I also inherited some hands from an old watchmaker shop, maybe some will fit - but I am not sure how to measure the diameter of such small a hole in hands (?).

Thanks for all your kind help - I really hope to bring this watch back to life (affectional value for us).

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[Seiko7A38]

Looking at your photos of the crown / stem, I don't think that the stem itself is bent. To my eyes, it looks more like the threaded part of the crown is bent. Seiko stems usually only thread into the crown for a couple of millimeters. It may be possible to straighten it by bending it, with the stem held in a pair of pliers or vice. Be careful, deciding which direction to apply force; you'll probably only get one chance. I've successfully straightened one or two crowns in my time. I've also broken a couple trying. If you have to buy a new stem (even one that comes with a new movement), the threaded part will need cutting to length. Stems are made in hardened steel, so you'll need something like a Dremel tool (with cut-off wheel) to do it accurately. Most eBay sellers over-charge for stems. They come from Seiko supplied in a pack of three. They sell one for the price you would have to pay for three. If you end up having to buy a new crown (Seiko p/n 8K65BSSNW1), they always come with the O-ring fitted.

Sorry, If you don't want to buy the correct hand from Cousins UK, then I don't know what to else suggest. I have no idea where you'd find an alternative (other than eBay, etc.) - only that it needs to have a bore of 0.21 mm (that comes from the movement specification). There's no way that you could realistically measure it, other than by trial and error fit.

It really looks like it is the SPC235P1 - I am amazed you could recognize it just so
You mention that we would need the caseback number. I have included a picture, does that bring us closer?

If you read my previous post, you'll see I did include it. (I edited my post quite a few times, while I was composing it).

No idea where you could obtain the missing sub-dial hand without knowing the full 7T04-xxxx case-back number. Hmm.
I'm guessing that your watch is a 7T04-0AT0 (SPC235P1).

FYI - According to Seiko's database, there exist 10 different versions of 7T04-0AT0: with different colour dials or bezels, stainless, two-tone and gold plated versions; a couple on leather straps, the rest on bracelets. The sales code SPC235P1 is specific to your watch.

[seikoenthusiast]

Thanks a lot for your reply!

This is my first time restoring a watch, so please bear with me - but I really want to learn!

You were completely right about the crown / stem issue. It turned out it was the threaded part of the crown that was bended. I unscrewed it from the stem and tried to bend it back, but unfortunately it only bended the lower part of the threaded part. So no luck unfortunately. I might have to get a new crown. I have inherited a stock of different crowns, not original seiko though, but could I in theory use any crown if it just fits the stem diameter? Or is there any other measurements I must take into account?

I wrote the seller of this add https://www.ebay.co.uk/itm/396881613446

He confirmed that the movement comes with the stem included and that it has a 0.9 mm thread diameter, but no o ring seal.

I'm trying to figure out if "all" I will need is the movement, the crown and the hand. It would be a pity to get these parts and then find that I miss several o rings or other parts.