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Tissot calibre 781 Service Walkthrough


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Tissot calibre 781 Disassembly (Please sort the images by name in ascending order)
Tissot calibre 781 Assembly (Please sort the images by name in ascending order)
Tissot calibre 781 ranfft facts

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Some time ago my brother handed me this Tissot dress watch from the mid-1960s housing a Tissot calibre 781. My brother collects watches but doesn’t tinker with them (yet). Anyway, I thought it would be interesting to give this Tissot 781 an overhaul (you always learn something). It did seem to run and being a 17-jewel manual wind watch I thought a service shouldn’t take too long or pose any challenges in particular.

Anyway, when I removed the case back, I noticed to my surprise that the balance had stopped. I thought “that’s funny”, as it was fully wound and had been ticking along fine while I was looking at the dial. Going deeper I realized that the one of the balance staff pivots was broken off. So, I called my brother and told him the bad news and that I had no experience replacing balance staffs. Well, my brother didn’t become too upset about this but simply told me to keep the watch and possibly repair it in the future if and when I would learn how to replace a balance staff.

I wasn’t sure I was ready for it, but life is unpredictable so I thought that it was now or never that I would learn how to replace a balance staff and get the necessary tools to do it. Long story short, I did learn how to replace a balance staff and the watch is now ticking along just fine. In the process I got first class help and illustrations from my fellow Swede @HSL, and if you are in the process of learning how to replace a balance staff, I do recommend reading the following thread where you’ll find HSL’s (and other helpful) posts about this “Staff replacement, balance wheel wobble”.

To call this post of mine a “Service Walkthrough” is perhaps a bit of a stretch as the pictures don’t include any oiling suggestions and/or tips/instructions. Nevertheless, I’m thinking that the pictures still might be useful to anyone servicing this calibre and perhaps pondering in what direction the main spring should go and/or what screws to use where, and so on.

Edited by VWatchie
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14 hours ago, oldhippy said:

Very nice clear photos. What did you use to take them?

Thanks for you kind words!

I simply use an iPhone 8 and a $10 clip-on macro lens. I used to have an iPhone 6 and it worked just as well, but the battery died and I had to "upgrade". The "secret" is the lighting. I move around the bench light quite a bit until I get the best focus and clarity. Also, I always support my hands against the table and move the phone back and forth to get the best possible focus. It takes some practice and experimenting. In the beginning it used to happen that I dropped, or almost dropped the phone on the movement, which can lead to some pretty dramatic damage, of course, but after some practice and experience I got the hang of it.

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That one with the black dial is one of the best ones from Tissot I think, for a while now they lost their charm and gone with the massproduced look. And great work with it!

 

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  • 2 weeks later...
  • 2 years later...
1 hour ago, lexacat said:

Thanks for this write up! I've got a 781 in pieces

Me too! Well, I have the automatic 783. But same stage of servicing. 

 

13 minutes ago, VWatchie said:

Good morning!

image.png.89dbadc0a6df8d9721d788b2bf9658e2.png

It pretty much looks like this.

Great, thanks! I ordered one like this and should hopefully receive it today! 

I also ordered a clip-on "microscope" with integrated LED light. Let's see what that can do. I'll post pictures soon. 

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23 minutes ago, Knebo said:

Sure! 

I was going to wait until I can report on it's quality, but here you go already:

https://www.fishersci.com/shop/products/micromini-20x-led-pocket-microscope/S81142

It's getting good reviews on Amazon. I'm very interested to learn how it works out, so please report back. Getting the best light can sometimes be difficult, so maybe this can help.

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6 hours ago, VWatchie said:

It's getting good reviews on Amazon

Yes, I bought on Amazon (.fr), but posted a country-neutral link (when I open an Amazon.com link on my phone, it wants to switch the whole country setting of the app...).

I got today and will test in the evening (if my wife lets me). I'll post pictures soon!

 

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Ok, well, I've played around with it for a little while. 

Here is a first review :

0. Of course, a lot depends on the quality of your phone camera. I have a pretty good one in my Samsung S22. 

1. The device is held to the clip by a magnet. It works ok, but not great. 

2. The object needs to be WITHIN the transparent part of the "microscope" (see red arrow). Even 1mm outside of it (like the recess of jewels on a bridge) and it won't focus. 

Screenshot_20231015_000210_AmazonShopping.thumb.jpg.2cd7960ac0fe6d44e5e6b8d2bbdc203a.jpg

So, if you want to inspect a small part individually and it fits into the space - great. Here's a picture of a very small jewel (cracked).

20231014_225325.thumb.jpg.7f6a72a8015c7aea17dd0e5612190a99.jpg

3. Note: you need to use 3x to 7x digital zoon in addition to the "microscope". Without zoom, you'll only see a rather small circle on your phone screen. 

4. To be able to use it on anything in an assembled movement, like inspection of jewels or pallet fork lubrication, I needed to break off the transparent plastic. While I had to break it a bit, I can still reinstall it for photos like in point 1. 

Having removed it, the light is no longer diffused and shines from an angle. Still usable, but not ideal. 

It is very fiddly, because the fixed focus tolerance is literally 1mm. Incredibly hard to stay in focus. 

I was still able to get this shot (note: non-serviced scrap movement):

20231014_220532.thumb.jpg.e77c243155bac6e8f0e4ebd9a4b65306.jpg

 

5. Now, I've posted my best two shots after 30min of trying. In sum, I'm not fully convinced of the device....

6. ....especially in comparison to the other macro lens that I bought. The Apexel 12x/24x lens: https://www.shopapexel.com/products/professional-12x-24x-advanced-macro-lens

Basically, it's like @VWatchie's lens with an additional/optional second 2x lens (thus combining to 24x).

It has no light, but I found it less bulky and overall easier to use. And importantly, there is a slightly larger margin of focus. I.e. the phone can adjust focus a little bit - maybe within a tolerance of 3-5mm. That helps a lot. 

I took this picture with it:

20231014_220108.thumb.jpg.a97f52de657b0c6a5ba5c9b313c84ba7.jpg

 

In the end, I'll properly use this one much more. Both with the single 12x lens as well as with the second lens.

Light is a challenge, though, especially with the double lens because you need to be very close to the object (~5mm),giving you very little chance to shine light in between. The consequence are pics like this:

20231014_231153.thumb.jpg.b3b9cda329764006530edf385124665b.jpg

 

That's it for now. More to come eventually. 

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Thanks for the report @Knebo, much appreciated. I think I'll pass on the version with the built-in light, but the other 2x lens seems interesting as it can give 24x magnification when needed.

I have a stereo microscope for inspection and some work such as oiling jewels, but when I only need to inspect something I sometimes just take a picture with my macro lens,  and then zoom in on it.

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19 hours ago, VWatchie said:

Thanks for the report @Knebo, much appreciated. I think I'll pass on the version with the built-in light, but the other 2x lens seems interesting as it can give 24x magnification when needed.

I have a stereo microscope for inspection and some work such as oiling jewels, but when I only need to inspect something I sometimes just take a picture with my macro lens,  and then zoom in on it.

I'd agree with that assessment. 

I also ordered ANOTHER product now. This one: https://www.shopapexel.com/products/ms009-hd-portable-smartphone-microscope

Not sure about the actual magnification, but most importantly it has an integrated LED light and hopefully the indicated focus distance 5.5-7mm is from the casing/black ring, and not from the lens (which is recessed). If the latter, it'll be the same issue as the Carson microscope.

I'll let you know on Wednesday when I receive it.

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18 minutes ago, Knebo said:

That looks like it could be a better option. Although it wouldn't fit on my iPhone 8 I'm still interested to know how it works out. Sooner or later I guess I'm going to have a compatible phone.

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2 hours ago, Knebo said:

Why would it not fit the iPhone?

 

You're right, my bad! I was looking at a different product (or accessory) and for that, you would have to select for what type of phone. Excellent! Looking forward to your impressions.

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On 10/14/2023 at 1:08 AM, Knebo said:

Me too! Well, I have the automatic 783. But same stage of servicing.

That reminds me Something from your discussion somewhere else on the message board should be added to this discussion.

On 5/27/2021 at 6:28 AM, VWatchie said:

To call this post of mine a “Service Walkthrough” is perhaps a bit of a stretch as the pictures don’t include any oiling suggestions and/or tips/instructions. Nevertheless, I’m thinking that the pictures still might be useful to anyone servicing this calibre and perhaps pondering in what direction the main spring should go and/or what screws to use where, and so on.

One of the things that make servicing a watch a lot nicer is if we can combine pictures with technical. But typically we don't get technical the best we could ever hope for is a parts list. Because typically technical does not get scanned even if it does exist. This is because typically the information out there was scanned for the purposes of parts identification not scanned because somebody wanted servicing information.

So that means conceivably the information is available in physical form somebody has to just feel motivated to scan it like for another discussion on this group for instance. Then when you look at the documentation number 23 is a bit confusing as a PDF and even confusing and physical form. It's actually two separate documents with the same number? So the second part of 23 was just scanned with the first part so you have to go to the back section for assembly reassembly and lubrication etc. basically it's confusing. Then the other document was because there was a revision based on your Serial number.

 

 

 

Tissot Service Technique No 30 Modifications on Calibers 782 783 784.PDF Tissot Service Technique No 23 781 782 783 784.PDF

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On 10/16/2023 at 9:11 AM, Knebo said:

I'd agree with that assessment. 

I also ordered ANOTHER product now. This one: https://www.shopapexel.com/products/ms009-hd-portable-smartphone-microscope

Not sure about the actual magnification, but most importantly it has an integrated LED light and hopefully the indicated focus distance 5.5-7mm is from the casing/black ring, and not from the lens (which is recessed). If the latter, it'll be the same issue as the Carson microscope.

I'll let you know on Wednesday when I receive it.

So, did you get it and are you happy with it? Thanks!

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Hi @VWatchie,

Thanks for the reminder! 

I did get it. 

Pros:

- the integrated light is useful 

- you have about 5mm focal length, which, for example, is just enough to cover the distance between train bridge and pallet fork. 

- magnification is decent

Cons:

- the light is not very strong and will struggle to properly illuminate the pallet fork if it's 5mm away... 

- magnification is like a macro lens. Nowhere near "microscopic". 

 

In the end, it's good, useful but not really a revelation. As a result, I haven't used it much so far. 

Here are a few pictures I was able to take:

20231018_211120.thumb.jpg.7c902379f8e85236e5da9208f4e1901d.jpg20231018_210850.thumb.jpg.259bb6230b5b1f70cf24b98e9b5d963c.jpg

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