Problem With Tissot 781-1 Movement

[Tricati15]

I`m a complete novice with watches having just attempted to tackle an issue with a Tissot Seastar (with 781-1 movement) purchased recently. Initially the watch was keeping reasonably accurate time, and then started to gain hours in a day due to a blob of lubrication on the balance spring. It was taken to a watch repairer who removed the offending oil; the watch then kept good time for a week or so then stopped. It was returned to the repairer only for him to say - after leaving it with him for inspection - that the hairspring was twisted....hmm. Apologies for the history, but I wanted to demonstrate that the watch had been working properly in the past.

Having viewed the excellent Watch Repair Channel videos to a point where I felt confident in tackling the problem, I decided to attempt an inspection/repair myself. Firstly I bought an identical movement (for spares/repair) from ebay, which had the essential balance assembly including the hairspring which appears to be in good order. If the original watch indeed has a twisted hairspring, then a straight swap from the spare seemed logical; however on careful examination, the Incabloc`s brass lyre shaped clasp (pic 1, I`m pointing to the bit that`s remaining)) showed it to be broken in two parts, so my first question is please, how does one remove the clasp? ( I want to take the good one from the original watch to the spare`s). Secondly, in Mark`s video on `How to align the hairspring to set the watch in beat`, he demonstrates the re-positioning  of the hairspring on the balance wheel to correctly locate the impulse jewel in-between the banking pins. I can`t see either of the items on the 871-1 movement with the balance assembly in place so I marked the balance wheel to show the position of the jewel and also the centre of the banking pins on the watch`s top plate, (pic2. ), and as can be seen, the two were slightly out of alignment.  I found though, if I moved the part that retains the end of the spring, (pic3), it would align  the mark on the balance wheel to the corresponding mark on the top plate. (Apologies for the lack of correct part identification). Is this method permissible? Lastly, the `lever` I`m pointing to in pic4, is this the co**BLEEP** `advance/retard` adjustment lever? The fine adjuster (which adjusts the co**BLEEP** one a small amount) is shown below it.

                                                                                    Thanks for your patience!           

          

[CKelly]

Hi,

If you are pointing to your spare movement it would probably be easier for you to remove the good balance complete with hairspring and transfer it over to the good balance cock. Replacing those incabloc springs can be a bit tricky, and it also appears as if the cap jewel is missing but that may just be the picture.

[Tricati15]

Thanks for your advice. You`re probably right in suggesting I transfer the balance and hairspring, but don`t know if I`m ready in attempting a h/spring removal yet! but I suppose if I`ve come this far...  Refering to pic number 014, is moving the lever I`m pointing to a correct method in moving the jeweled cock on the balance wheel? 

                                 Thanks again

[Marc]

Hi Tricati,

 

The lever you are pointing to in pic 014 is the adjustable hair spring stud holder and is exactly what you need to move to get the balance in beat.

The lever indicated in pic 017 is the co**BLEEP** adjustment for rate, fine adjustment is by the screw with the graduations around it.

 

Adjust the beat error first to get the tick even, then adjust the rate.

 

As CKelly pointed out, it may be easier to swap just the balance/hair spring over rather than repair the incabloc setting on the donor cock.

[Tricati15]

Thanks Marc.   I`ll persevere until it`s sorted.

[Tricati15]

I bit the bullet and removed the damaged hair spring and balance wheel from the watch and replaced it with the good one from the donor movement. With the balance jewel centralised via the adjustable hair spring stud holder (as Marc suggested) and the co**BLEEP** adjustment lever set as far as it will go anti-clockwise (before coming up against the stud holder)....and the watch started, it gains an hour or so per day. If I move the stud holder as far as it will go anti-clock (and hence the balance jewel out of beat, [the watch will still run though]) and likewise the co**BLEEP** adjustment lever in the same direction, the movement still gains a lot. So I attempted moving the hairspring collet in the manner Mark demonstrates in his video ie. a screwdriver in the small slot of the collet. Unfortunately it doesn`t have a user friendly slot or the facility (space under the collet) to remove it by levering, as again demonstrated in the video. Is there a special tool for removing the collet from the 871-1 movement or can anyone suggest another method of regulating the time?

        

                                                               Thanks

ps. Although both balance wheels are from 871-1 movements, their design shapes are different: could this affect the timing? 

  

[rogart63]

I don't think you should need to take the collet of to adjust it . Their should be enough adjustment in the lever you are pointing at in picture 014 . But it 's very difficult to set without a timegrapher . Just a little touch of the lever could get it from 0,1 to 2,5 in beaterror . Same is for the timesetting . Assembled a unitas 6325 today . It was out in beaterror 3,0 and adusted it to 0,1 . But the timeerror was +625 second per day at first . 1 mm of adjustment bring it down to 5-6 sec per day .