Men's Longines Quartz - L761.2 movement - screw missing - Sentimental Value

[DeepBlue]

My father-in-law died several months ago, and my wife now has one of his watches - it's a Longines Quartz watch.  Anyway, several months before he passed he asked my wife if she could get a new battery put in it.  My wife took it to a kiosk (the ones who repair shoes and cut keys).  Anyway, when she went to pick it up the guy said it was broken!

Just yesterday I decided to have a look at the watch as it is of sentimental value now - I want to get it working!

It's a simple pry back, so I had a look.  Now, the battery appeared to be in the wrong way around on this watch (the +ve polarity should be towards the dial face and the battery -ve polarity towards the back of the watch), and the metal saddle that secures the negative end was not screwed down at one end due to there being no screw!  I suspect the repair guy undid this saddle to remove the old battery, subsequently lost the screw, and then put a new battery in upside down!

Does anyone know where I can get a screw that will fit the other end of the saddle so I can secure the new battery - the movement says L761.2.

See attached photo showing battery location and securing saddle with only one screw attached:

 

[JohnR725]

One of the sad realities of quartz watches are people changing batteries who are not skilled at doing this. On the other hand it brings index to work for people who are you get the fix their mistakes sometimes. What typically happens is somebody takes the wrong screw out and it flies away.

Then we really need a better picture so I found one at the link below which also had the other thing I needed off a better picture which is what is this equivalent to if it's equivalent to something else Usually the equivalent number in other words whoever they purchased it from would be lurking somewhere else on the movement which is why we need a good picture. But it does appear to be they are the same I'm attaching both technical bulletins. Plus and stepping out a image so everyone can see the problem of what happens when you take out the screw. The battery strap is under a lot of tension one screw is meant to come off because it's attached to the strap the other  screw which I assume is the missing one is meant to stay on the watch. Usually they take the wrong one off its catapulted into the stratosphere and their confused. Because the technical drawing is a nice picture I'm snipping out a image for all to avoid this stupidity. Notice the helpful arrow it tells you which screw you're supposed to take out.

Is nipped out a lot of images is a reference to cousin screw. I have  text below that came from best fit their telling us they are a number which has the X. Then there telling us the factory number and of course it's been discontinued. Then what I was hoping for was more cross references that it cross reference to lots of watches which it does not. Unfortunately bestfit  does not even have Longines Which is why it's not even in the cross reference list interestingly enough it does cross-referenced tour Omega watch. But you do have a cousin's number so you can order it from cousins. Or if you are in the US you could use the best fit number in order from the material houses.

 

https://www.worthpoint.com/worthopedia/longines-l761-eta-959001-dial-hands-1774788213

 

5334_Longines L761.2.pdf 673_ETA 959.001.pdf

[clockboy]

Agree with John regarding un- skilled changing batteries. I was asked to look at a rotary (chronograph style) after the customer had had its battery changed at a well known high street shoe repairers who also offer to service watches. The problem was that the repairer was obviously unaware that it had a screw down crown and had just ripped it out stripping the thread of the crown. I replaced the crown and re fitted the battery which was also upside down. 

[VWatchie]

I just don't get it how customers are willing to accept all this battery changing sloppiness. A colleague of mine had her battery replaced at a shop selling mostly watches (Ur&Penn) and when she got her watch back the case back was horribly scratched up. She complained about it but the staff simply said that it didn't matter as no one would notice. My colleague decided not to make a fuss about it, accepted their argument and paid for the service. I just gasped when she told me this story, and it was a pretty nice $500 or so watch as I remember it. I would have held the shop 100 % responsible.

[watchweasol]

I think this is down to untrained staff and not knowing how to use the tools. Down to some basic training and understanding that the watch no matter what cost is the customers and should be treated with respect and returned in good order.

[DeepBlue]

4 hours ago, JohnR725 said:

One of the sad realities of quartz watches are people changing batteries who are not skilled at doing this. On the other hand it brings index to work for people who are you get the fix their mistakes sometimes. What typically happens is somebody takes the wrong screw out and it flies away.

Then we really need a better picture so I found one at the link below which also had the other thing I needed off a better picture which is what is this equivalent to if it's equivalent to something else Usually the equivalent number in other words whoever they purchased it from would be lurking somewhere else on the movement which is why we need a good picture. But it does appear to be they are the same I'm attaching both technical bulletins. Plus and stepping out a image so everyone can see the problem of what happens when you take out the screw. The battery strap is under a lot of tension one screw is meant to come off because it's attached to the strap the other  screw which I assume is the missing one is meant to stay on the watch. Usually they take the wrong one off its catapulted into the stratosphere and their confused. Because the technical drawing is a nice picture I'm snipping out a image for all to avoid this stupidity. Notice the helpful arrow it tells you which screw you're supposed to take out.

Is nipped out a lot of images is a reference to cousin screw. I have  text below that came from best fit their telling us they are a number which has the X. Then there telling us the factory number and of course it's been discontinued. Then what I was hoping for was more cross references that it cross reference to lots of watches which it does not. Unfortunately bestfit  does not even have Longines Which is why it's not even in the cross reference list interestingly enough it does cross-referenced tour Omega watch. But you do have a cousin's number so you can order it from cousins. Or if you are in the US you could use the best fit number in order from the material houses.

 

https://www.worthpoint.com/worthopedia/longines-l761-eta-959001-dial-hands-1774788213

 

5334_Longines L761.2.pdf 3.64 MB · 1 download 673_ETA 959.001.pdf 3.43 MB · 2 downloads

What a comprehensive answer - you've blown me away!!!  Thanks JohnR725!  So I guess I'll have to get on to the cousinuk.com website to find that screw?  I was hoping there might be someone in Australia, but I can wait - can't cost that much to ship a screw?

[Repivot]

Another alternative would be to find a watchmaker or even eBay which you can get a whole spare movement. Seeing this is a sentimental watch and this particular model is no longer produced, it's good insurance to have your own parts movement or two for future repairs. I believe the ETA model is correct or nearly so. You can look on the plate by the coil and see if it's stamped like in the technical drawing. I'm pretty sure while it's marked Longines, the plate will still be stamped with the ETA model number.

[JohnR725]

4 hours ago, DeepBlue said:

I was hoping there might be someone in Australia, but I can wait - can't cost that much to ship a screw?

You'll notice that most people don't have a location on their profile. The problem with not having a location or even a country is that generic answers have to be given because don't know where you're located. Although a lot of times the answer is not going to change even if I did know where you're located.

I'm attaching another technical sheet because it's apparently the same movement. Sometimes it's hard to tell with interchangeability whether everything would interchange 100%. But the weird aspect is that the eta  and Omega at least for this screw do appear to interchange. But conveniently for the Longines It just isn't showing up on the cross reference. Probably because everyone looks at the alternative number knows what it is perhaps?

4 hours ago, Repivot said:

stamped with the ETA model numbe

It's why I was hoping for a much better sharper photograph because usually the other number is Usually visible somewhere. Like for instance in the really crappy image that I've attached you can see where the number is located.  unfortunately the crappy photo I found online does not give us enough resolution.

4 hours ago, Repivot said:

Seeing this is a sentimental watch and this particular model is no longer produced, it's good insurance to have your own parts movement or two for future repairs.

Always a good idea for sentimental watches if you could acquire spare parts or replacement movement. Especially for electric watches where components can go out with possibility of no replacement. Or somebody's careless changing your battery and they nixed the coil and you need a new one of those it sometimes challenging to find that stuff. Usually it ends up easier to find a replacement movement if you can.

 

 

Omega 453_1377_complet_2335.pdf

[jdm]

15 hours ago, DeepBlue said:

Now, the battery appeared to be in the wrong way around on this watch

SInce you didn't mention- have you verified first that it works with the battery fitted correctly? 

[fjseal]

I wonder how many high street repairers know that you should not handle a battery with your fingers and you must use plastic tweezers when fitting the new one.

[DeepBlue]

4 hours ago, JohnR725 said:

You'll notice that most people don't have a location on their profile. The problem with not having a location or even a country is that generic answers have to be given because don't know where you're located. Although a lot of times the answer is not going to change even if I did know where you're located.

I'm attaching another technical sheet because it's apparently the same movement. Sometimes it's hard to tell with interchangeability whether everything would interchange 100%. But the weird aspect is that the eta  and Omega at least for this screw do appear to interchange. But conveniently for the Longines It just isn't showing up on the cross reference. Probably because everyone looks at the alternative number knows what it is perhaps?

It's why I was hoping for a much better sharper photograph because usually the other number is Usually visible somewhere. Like for instance in the really crappy image that I've attached you can see where the number is located.  unfortunately the crappy photo I found online does not give us enough resolution.

Always a good idea for sentimental watches if you could acquire spare parts or replacement movement. Especially for electric watches where components can go out with possibility of no replacement. Or somebody's careless changing your battery and they nixed the coil and you need a new one of those it sometimes challenging to find that stuff. Usually it ends up easier to find a replacement movement if you can.

 

 

Omega 453_1377_complet_2335.pdf 148.18 kB · 1 download

Again, thanks so much for the thorough and detailed response!

And, sorry - location (Melbourne, Australia) fixed it on my profile now!

Okay, that number near the orange/red coil is absolutely microscopic!!!  Large magnifying glass required - I'm pretty sure it says 959001.

Inscriptions Outside The Watch:

Face: LONGINES, Quartz, 761 SWISS 6222

Back Cover: STAINLESS STEEL BACK, 19768055

Inside Back Cover: LONGINES, SWISS MADE, 6222 761

Inside The Watch (Movement): L761.2, LONGINES, 54934233, UNADJUSTED, SIX 6 JEWELS, SWISS, 959001

 

 

 

[DeepBlue]

10 hours ago, Repivot said:

Another alternative would be to find a watchmaker or even eBay which you can get a whole spare movement. Seeing this is a sentimental watch and this particular model is no longer produced, it's good insurance to have your own parts movement or two for future repairs. I believe the ETA model is correct or nearly so. You can look on the plate by the coil and see if it's stamped like in the technical drawing. I'm pretty sure while it's marked Longines, the plate will still be stamped with the ETA model number.

Thanks.  Microscopic number stamped next to coil is 959001.

 

The battery was upside down when I first opened the watch (+ve end facing me), so I took out the battery and tested it with the DMM (about 1.58V).   When I noticed the screw was missing from the battery clamp (saddle I called it), and the clamp was sprung up, I used the battery in another watch that I needed the same 315 battery for.  I have now ordered several batteries (need to put batteries in other forgotten quartz watches).  I take your point, even without the screw to clamp down the saddle, I should have tried to test the watch with a battery right way around to see if that was the only problem with the watch! 

I'll try and purchase the missing screw and take it from there?

[Michael1962]

Does the battery being reversed cause any issues with the electronics?

[JohnR725]

3 minutes ago, Michael1962 said:

Does the battery being reversed cause any issues with the electronics?

Doubtful in this particular case because the screw missing it's not making contact to the circuit.

It's an interesting question fortunately watch batteries don't have a lot of power versus other things it shorted out like a car battery that makes for a really interesting effects when you short that. But a lot of people do put the batteries in backwards it doesn't seem to be an issue once it straightened out.

Sometimes when batteries go in the wrong they can short out that causes issues. Then it's conceivable the battery leaks and makes a mess.

[Michael1962]

Maybe diode/s on the PCB to prevent anything happening when the battery is installed correctly?

Maybe the designers thought about that very error.

[LittleWatchShop]

6 hours ago, Michael1962 said:

Does the battery being reversed cause any issues with the electronics?

Generally speaking, this circuit illustrates current path on a CMOS IC (the chip on the pcboard of the watch).  As you can see there are two reversed-biased diodes at the input protection...and though not obvious to the casual observer...there are series reverse-biased diodes throughout the entire integrated circuit.

The cutin voltage for a pn junction is around 0.6 to 0.7 volts, so two in series would be 1.2 to 1.4 volts.  With a 1.5 volt battery, that leaves 0.1 to 0.3 volts across whatever the series resistance of the battery plus whatever series resistance in the circuit path.  A 357 battery (e.g.) has a series impedance at 40Hz of 5 to 15 ohms.  The spec does not give me a dc resistance, but for grins I will assume those numbers are for dc (they are not), so if that were all of the resistance, then the current you would expect would be between 7mA and 60mA.  I kinda doubt these currents would kill the IC, but that is a guess.

The above is very simplified analysis.  If I had a good battery model, I could run a simulation that would be more informative.

Somebody should try it!