Jump to content

Tissot calibre 781 Service Walkthrough

Recommended Posts

Posted (edited)

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


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
  • Like 3
  • Thanks 2
Link to post
Share on other sites
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.

Link to post
Share on other sites

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!


  • Thanks 1
Link to post
Share on other sites
  • 2 weeks later...

  • Recently Browsing

    No registered users viewing this page.

  • Topics

  • Posts

    • Nucejoe has made some good points about the calendar mechanism. If the watch physically stops at least the hands stop and the secondhand keeps going that means the watch train is running it means that it's a disconnect between the gear train and our minute hand in calendar mechanism. The Canon opinion which I'm going but I guess is the type that snaps into a drive wheel. The drive wheel is driven by the gear train the Canon pinion goes on the post there is no friction there. If the friction between the drive wheel in the Canon pinion disintegrates which he can then with the least amount of friction like a calendar mechanism it just quit striving. The hands come to a stop the watch keeps running the secondhand keeps moving because it's independence of all of this. It should have been obvious when the watch was going to gather and you check the setting mechanism before you put the calendar on you would have noticed zero friction as a guess. Even now when you go into hands setting you'll feel like there's no friction at all. Then the reason why the calendar mechanism works when you manually rotate the hands is because the setting wheel is driving the Canon pinion directly which is driving the calendar mechanism and that our wheel and all of that so all of that will run from that we just will not run from the gear train running the drive wheel that's connected to the Canon pinion. But that's just my wild guess and then we throw in Nucejoe's possible calendar mechanism increased friction than we need to really isolate all of this or we can continue to guess.  
    • I am not sure if I correctly understand you here. Only the seconds hand keeps running or minute and hour hands do move too, in case minute and hour hands move and show time right, then the fault is in date change train including date jumper mech, but if it doesn't show time correctly ( appear to loose time) then its loose canon pinion. You can tighten a loose canon pinion, use grease to lube it, not oil.
    • Thank you for your introduction and welcome to this friendly forum.
    • always confusing when it's two separate watches but I'm going to assume they're basically identical. What was their condition before you service them in other words did have a problem before and the problem came after you've serviced or was the problems there before? Then timing machine results you do have a timing machine don't you? In other words what's the running condition of the watch like of the watches barely running that would be an issue for a calendar change   then you fix the problem? so I'm guessing we only have to worry about the 2778 then? Yes this is what happens when you have multiple watches with too much going on it becomes confusing. then it would be helpful to have a picture of the dial side components because we didn't memorize every single calendar change mechanism. one of the places to look is the Canon pinion assembly in other words to visit have enough force to drive the calendar mechanism? I'm having to guess because I'm not finding a good tech sheet that shows the parts. If it's a kinda Canon pinion I think which is the Canon pinion that slips into her presses into with friction with the wheel if it no longer has and the friction then a cannot drive the calendar but if you manually set the watch that drives the Canon pinion directly and everything should function. then if you two of the parts list it would be listed as canon pinion with drive wheel. .But it would be helpful in the picture just to make sure http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&ETA_2778  
    • I think what the problem here is you're asking the wrong question. The question is what part number do I need so that I can end up with the correct balance? Or the correct balance staff for that matter? If you look at the second link it lists the parts for your watch. This is always where things get interesting? you'll notice for balance staff they list seven different ones. For balance complete they do show three but if you look at the part numbers there's only two. then I attached some images from bestfit online and of course additional problems perhaps. Notice you have lots of choices and probably only one that's right. then the physical bestfit book becomes interesting because is an indication that there are variations which is of course why there so many listed in the images. but fortunately it looks like you want the basic simple one which should be 100/66.  unfortunately for the third link it's out of stock. then providing this is the right staff number I snipped out a couple of more images of the bestfit book which is what the dimensions mean and the dimensions. One of the irritating things of the physical book is on the dimension chart if you're trying to find a particular staff you just have to be lucky to go through the list and find it it be really nice if they list of the sizes by the numeric staff also. http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&AS_1287 http://cgi.julesborel.com/cgi-bin/matcgi2?ref=AS_1287 http://cgi.julesborel.com/cgi-bin/matcgi2?ref=U\ZD]J http://www.julesborel.com/s.nl/it.A/id.151223/.f  
  • Create New...