Please Help Me Fix My Tawatec Watch?

[Heman]

Hello all,

I have a watch I would like to fix my self. It's made by TAWATEC, who is no longer in business. It's very similar to a Luminox and used TGS for lume. I will provide information to the best of my ability. 

Here is a link to some information about it. Here are a few pictures of the watch. 

 

 

I have had the watch since May of 2011. I had the battery replaced in Feb 2015 by a local shop. Less than a year later, I noticed that after taking a shower there was condensation under the crystal. I pulled the crown and left it sit to air out. After about a week I pushed the crown back in and the watch no longer worked. I wondered what caused it to leak. I then remembered I had to change the date on the watch a few days before condensation had got inside the watch. When I was trying to set the date I noticed that it was difficult to pull the crown out and it was more difficult to turn than usual. My guess was that the gasket/O-ring that is on the stem/crown was messed up and had ripped and water had entered that way. I left the watch sit for a year and used another watch as my daily driver. I'm hoping to get this one up and running again. So I recently decided to see if I could fix the watch myself. 

 

Here is what I have done and have figured out so far...

1. I was able to remove the case back by removing the 4 Phillips screws. Visually inspecting the O-ring that seals the case back, everything looks good.
2. The movement is a Ronda 515. The plastic ring that holds the movement inside the case says Ronda 515 # 6.
3. I was able to remove the crown and stem. Looking towards the inside of the crown there was remnants of the O-ring. After clearing the remnants and putting the crown back in, the crown moves freely. I also found remnants if rubber on the front of the dial.
4. After inspecting the battery, it looks to have leaked its electrolyte

What I would like to do first is replace the O-Ring that's on the crown and put a new battery in it. If I then determine that the movement is damaged, I can replace it later. 

What do I need to do to figure out what size of O-ring I need for the crown? I can take pictures of the crown/stem if needed. I also have analog calipers to use that are in inches.

Thanks for your time!

 

 

[jdm]

Almost certainly you will have to replace mov.t.

Gaskets sizes are measured with a metric digital caliper.

[Deggsie]

As jdm says, replace the Ronda unit. The 515 is not uncommon but before ordering, just check the overall height as there are usually 3 options for Ronda. I think 525li is also an option. The 515li has a full diameter battery which lasts something silly like 12 years.... provided it doesn’t leak of course [emoji51]


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[noirrac1j]

Hello @Heman, Welcome to the forum. If you live in the U.S. Esslinger material house has a movement that may be the one you're looking for:

If your movement is cooked, check the height to make sure the replacement is the same. Your watch has the date between 4 and 5 hour markers, but I think this would still be the correct movement. If ordering is a problem, I have an account with Esslinger and would be happy to help you.

 

J

[Heman]

Thanks everyone for their replies! I'm looking at this movement with the date window at the 4:30 mark. Just not sure about the height.

I was told by a watch repair store I went to yesterday that where the date window is matters because it determines where the feet of the dial attach to the movement and if I had the wrong one, the dial would be misaligned. 

 

[Heman]

I decided to check out Ronda's website for a listing of all their movements. Looking at the 515, all the stems are at the 3h position. Looking at my watch, the stem is at the 4h position. I'm starting to guess that they just used a 3h stem(it's the only option) but I'm not sure about the date placement.

 

For a second I was thinking/making assumptions about 2 things that I now believe are incorrect.

1. They can make the case however they want to and put the stem coming out of the case at the 4h position(instead of the 4h position). They can do that when making to dial correspond to the orientation in the case (making what would be the 12 position to the 11 position), but since there is a date in the movement, now the movement's 12 position and the dial's 12 position need to line up in order for the date to change at midnight.
2. When they make the dial and cut the date window, they can also orient it any way they want. The problem is that the date windows position to the crown is lower then anything listed since all the stems are at the 3h position.
    

I'm not sure what movement of the 515 they used..? The offsetting of the crown/stem really messes things up. I think that number 2 is more correct, so it's just a matter of finding a movement that has the stem at 4h.. How is that done on watches with the stems at the 4h or 9h position?

[jdm]

Movements are not made for a given crown or date position, they are all the same and just rotated. Of course for uncommon date positions like 6h, or even 4h with horizontal lettering, then a special date ring is used.

If the date wheel or the hands wheels height are different the original ones are used on the new movement, requiring it to be partially or completely disassembled and reassembled.

[Heman]

jdm,

Thanks for the reply. I understand what you are saying about a modified date ring. I think this watch is using a standard date ring since  the numbers are still perpendicular to the hand shaft. 

 

I don't quite follow the movement part and how rotating that doesn't effect what is being showed on the dial. I am attaching 2 diagrams. It's a drawing of the 515 movement with date and stem at 3h position. The second is the  same thing but rotating the crown to the 4h position.

First 3h

 

 

Second rotated to 4h

[Heman]

I don't see a way to edit the previous post anymore.... I had seen the option before and used it on a different post, but I'm no longer seeing it on either post....

I am new to the whole watchmaking art, so I may be completely off when it comes to what I posted above. Hopefully I was able to portray some of the issues I see with moving a crown to a 4h position as far as when the movement knows it's midnight and how that is reflected on the dial attached to the movement. I definitely don't know all the tricks of the trade. 

 

 

Edit: here is my edit for this post... I guess it is only active for a lil while. Makes sense  

Edited May 24, 2018 by Heman
testing edit :)

[jdm]

9 hours ago, Heman said:

 

I don't quite follow the movement part and how rotating that doesn't effect what is being showed on the dial.

You are overthinking this. Only the mov.t is rotated according to the desired crown position. The dial is made with the date window in the desired position and dial feet placed to fit into the mov.t. holes.

[Marc]

Dial feet positioning is determined by the crown position relative to the case. Take the standard arrangement of crown @ 3 on the dial and 90° clockwise from the 12 position relative to the case as the starting point. If you want to position the crown @ 4 on the dial but still have the standard arrangement of dial relative to the case you have to rotate both the movement and the dial feet position 30° clockwise relative to the dial and case.

The date ring printing is determined by the date window position relative to the movement (and therefore the crown). If you start from the standard position as above and want to move the crown to the 4 position relative to the case as above then you will either need to move the date window 30° clockwise on the dial and have the date @ the same position as the crown (in other words new dial but retain the original date ring and have the date display canted 30° relative to the dial and case), or use a date ring that is printed 30° offset anticlockwise to standard so that the date window can remain @ 3 relative to the dial and case.

I hope that the above makes sense (I find it slightly confusing and I wrote it, I may have got it wrong).

Either way I think that you will likely need to move the original date ring from the dead movement to the new one. Your watch has the crown @ 4 (30° offset from standard) and the date @ 4:24 (42° offset from standard). I could be wrong but this is an unusual arrangement which could well be unique to this watch, in which case the date ring is also unique to this watch. As such a standard movement will need the date ring switched with the original to get everything to line up.

 

[jdm]

2 minutes ago, Marc said:

I could be wrong but this is an unusual arrangement which could well be unique to this watch, in which case the date ring is also unique to this watch.

Not unusual and not a special date ring, it's the very standard one. Lettering would be perfectly horizontal if crown and date were at 3.

[Marc]

37 minutes ago, jdm said:

Not unusual and not a special date ring, it's the very standard one. Lettering would be perfectly horizontal if crown and date were at 3.

If you look at the photo in the original post you can see that the date is offet from the crown by 12° so they are not concurrent.

Date wheels have 31 divisions which means a rotation of just over 11.61° at each date change. If you were to rotate the date window back by 12° to bring it into line with the crown but still use the original date ring the ring would be out of alignment with the window by just under 0.4°, not a lot but enough to notice and be really irritating.

[jdm]

Again, this watch is using the standard date ring that aligns at 3h and then every 360/31 degs.
The OP can take a picture with the dial removed to show that.
The date window is cut to align perfectly.

[Marc]

8 hours ago, jdm said:

Again, this watch is using the standard date ring that aligns at 3h and then every 360/31 degs.

I'm not sure that we are talking about the same watch. As can be seen in the picture below (taken from the original post) the watch has the crown @ 4, and the date @ 4:24;  30° and 42° offset from the 3 position respectively.

To bring the date window alignment concurrent with the crown (as would be the case with a watch that has both date and crown at 3) the date window in the dial would have to be moved 12° anticlockwise relative to the dial numbering, which would put the date at 4 concurrent with the crown. If you then move the dial feet 30° clockwise you would then have a dial that would result in both crown and date window at 3, however let's keep the date window and crown at 4.

The problem is that the date wheel detents which hold the date ring in the correct position to show the date in the window are spaced at 11.61290323° (360/31) intervals and not 12°, and the date jumper is fixed in the same position in the movement regardless of date window position. Therefore displacing the date window in the dial by 12° without displacing the date wheel printing relative to the date wheel detents by the same 12° will result in a misalignment between window and numbers of ≈ 0.387°.

The drawings below illustrate the problem, the first in general and the second in detail.

There are in fact 31 possible positions on a dial where you could site the date window without having to change the date wheel printing relative to the date wheel detents and they are at ≈ 23 minute and 13.548 second intervals. To put it another way the drawing below shows a date wheel that aligns correctly with a date window at 3, with possible date windows at all the other hour positions. Only the 3 position is correctly aligned.

If the OP simply does a movement swap with a standard (date @ 3 position) movement without changing out the date wheel for the original there will be a slight but noticeable angular misalignment between the window and the date wheel printing.

[Neileg]

Wow. We’re putting a lot of thinking into this and the plot seems to be lost.

1. A movement doesn’t know when midnight is in any precise way. Most watches change date between 23:00 and 01:00. Rotating the dial 5 minutes(time not angular rotation) is unnoticeable.

2. The date aperture can be anywhere on the dial. As long as 9 is showing on the ninth, it works. You may need to adjust the printing of the date ring if that matters.

3. The printing of the dial and positioning of the dial feet is determined by the case and movement orientation, not by anything intrinsic to the movement.

 

Naturally you will find some watches that break these rules, but not many.

 

Neil

 

 

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[Marc]

5 hours ago, Neileg said:

1. A movement doesn’t know when midnight is in any precise way. Most watches change date between 23:00 and 01:00. Rotating the dial 5 minutes(time not angular rotation) is unnoticeable.

Correct. The timing of the date change is determined by precisely where you position the hands when you reinstall them.

5 hours ago, Neileg said:

2. The date aperture can be anywhere on the dial. As long as 9 is showing on the ninth, it works. You may need to adjust the printing of the date ring if that matters.

Correct, and this was the point of my post above. The printing of the OP's date ring is unique and specific to the orientation of date window to crown on his particular watch. Some of the previous advice seemed to be suggesting that he could do a movement swap with a standard movement that has a different date window / crown orientation and not have to change the date wheel to the one specific to his watch. Further up the thread I had pointed out that this would result in a slight misalignment in the date window but my advice was being (quite strongly) questioned (no problem with that, it's part of the "scientific method" upon which all true learning is based) hence the detailed presentation of my arguments above. If the time I put into my post results in time and frustration saved by the OP when he sorts out his watch then it was time well spent.

5 hours ago, Neileg said:

3. The printing of the dial and positioning of the dial feet is determined by the case and movement orientation, not by anything intrinsic to the movement.

Correct.

 

[Tudor]

It could be a standard datewheel if the dial opening is placed so that it is centered over the date when locked on a detent. Maybe not “exactly” 4:00 but if it’s off a degree, or rotated slightly from radial it’s fine- not noticeable on the wrist certainly .

Look at it from a cost perspective: new watch company. Make all new dials AND datewheels, or just dials? I’m almost willing to bet it’s a standard date wheel and the dial aperture location is “tweaked” to acomodate it.