ETA 955.114 missing part on PCB query

[tIB]

Just taken delivery of an old 955.114 - first thing I noticed was a missing part on the PCB - any ideas what it was for? Trimmer for accuracy? Assume it's optional as the later ones don't have them?

 

[Neverenoughwatches]

38 minutes ago, tIB said:

Just taken delivery of an old 955.114 - first thing I noticed was a missing part on the PCB - any ideas what it was for? Trimmer for accuracy? Assume it's optional as the later ones don't have them?

 

Certainly looks like that is what's missing

[watchweasol]

Hi.  Judging from the outline  I would say you are right, the trimmer capacitor is missing attached service sheet / parts list

612_ETA955.102,955.112,955.122,955.132,955.402,955.412,955.422,955.432.pdf

[tIB]

I haven't actually tried running it yet as I'm not sure what hands I have that fit, though I'm assuming since it wasn't on later versions it should run ok without, albeit without the 0.5 +/- seconds a day adjustment? 

 

(I have another PCB I can try if not, though not sure it works...)

Don't know what I was messing around at actually- staring at a movement isn't going to check if it works!

Battery in... ticking happily... will have a look at accuracy tomorrow...

[AndyGSi]

I'm surprised it runs without the trimming cap.

[watchweasol]

It’s possibly catered for within the chip using the inhibition method whereby it monitors the pulse rate and adds or drop pulses to reach stability. Used on a lot of the modern quartz watches.  It’s a bit more complicated than my explanation , but that’s the gist of it.

[tIB]

21 minutes ago, AndyGSi said:

I'm surprised it runs without the trimming cap.

I was too, though it was sold as running and since the part was removed in later runs I guess it's one that can be/has been bridged, though there's no sign of that at first look. 

9 minutes ago, watchweasol said:

It’s possibly catered for within the chip using the inhibition method whereby it monitors the pulse rate and adds or drop pulses to reach stability. Used on a lot of the modern quartz watches.  It’s a bit more complicated than my explanation , but that’s the gist of it.

I guess whatever it was doing, which to my knowledge was +/- 0.5 seconds a day, was felt not needed since they removed it from the design.

 

Those old ETAs are great in my (admittedly limited) experience - managed to get the one this was possibly replacing back to life yesterday with a bit of fiddling. 

[JohnR725]

What's interesting is that they didn't just upgrade the entire circuit board.

5 hours ago, watchweasol said:

attached service sheet / parts list

I was curious about cross referencing to a newer movement that would not show the trimmer capacitor. Then I noticed something very peculiar the 955 xx2 series of movements at least as far as the circuit goes does not cross reference with the 955 xx4 watch. Even though as far as I can tell they look identical. I'm attaching the 955.114 technical.

 

ETA 955.114.pdf

[tIB]

13 hours ago, JohnR725 said:

What's interesting is that they didn't just upgrade the entire circuit board.

I was curious about cross referencing to a newer movement that would not show the trimmer capacitor. Then I noticed something very peculiar the 955 xx2 series of movements at least as far as the circuit goes does not cross reference with the 955 xx4 watch. Even though as far as I can tell they look identical. I'm attaching the 955.114 technical.

 

ETA 955.114.pdf 1.78 MB · 2 downloads

I think the xx2 was the replacement for the xx4 - maybe they used newer components in the PCB?

 

What I find vaguely interesting is that they changed that 114 circuit over the years without changing the revision number as I would expect, the trimmer capacitor being an example. 

[JohnR725]

51 minutes ago, tIB said:

I think the xx2 was the replacement for the xx4 - maybe they used newer components in the PCB?

you might find the link below interesting. Rather than searching for exact watch I just search for 955.

so for the 955.112 we find it's been discontinued. But we do get a replacement number which is not a 955.114.

then 955.114 does not appear to be discontinued and I now have found the difference. both normal flat line but 114 is a standard. Which of course means absolutely nothing other than there's some sort of different surname.

then the website down below is much more interesting when they used to have the mechanical watches now they just have their quartz watches.

https://shopb2b.eta.ch/en/catalogsearch/result/?q=955

 

[tIB]

2 hours ago, JohnR725 said:

you might find the link below interesting. Rather than searching for exact watch I just search for 955.

so for the 955.112 we find it's been discontinued. But we do get a replacement number which is not a 955.114.

then 955.114 does not appear to be discontinued and I now have found the difference. both normal flat line but 114 is a standard. Which of course means absolutely nothing other than there's some sort of different surname.

then the website down below is much more interesting when they used to have the mechanical watches now they just have their quartz watches.

https://shopb2b.eta.ch/en/catalogsearch/result/?q=955

 

That is interesting! In my head the .112 was the .114 replacement which the f06.412 eventually superceded. 

 

I'm certainly no expert though, I just know a little about these as they feature in one of my favourite watches - the CWC G10. 

[tIB]

And it's running accurately over 24 hours - more so than the one in the other watch I revived that does have the trimmer in place... that's maybe five seconds a day fast. 

 

I gave that ones trimmer a half turn to see if it makes it better/worse, but will probably swap this one in if it keeps on behaving...

[JohnR725]

3 hours ago, tIB said:

 

I gave that ones trimmer a half turn to see if it makes it better/worse, but will probably swap this one in if it keeps on behaving..

trimmer capacitors are quite interesting how they work. Unlike a variable resistor which might start off at zero and adjust to a maximum and stop. Trimmer capacitors typically do not have stops some of them might but in a watch they do not. The examples below have way more plates than you would have been a watch so basically you have two half round circles. When their maximum together you have your maximum capacitance. When there turned the opposites then you will have the least amount of capacitance. So turning it as you have done may not actually have the desired results. Typically you would have a timing machine for quartz watches and you would turn them very tiny quantities. Then yes even with a trimmer you can get down to a few seconds per day is happy really patient when you're adjusting and you also want to be careful not to press down on them as that tends to bring the plates together and then they have to readjust back to wherever they were plus if you push hard enough you can actually break the capacitor to visit uses ceramic for its construction.

[tIB]

24 minutes ago, JohnR725 said:

trimmer capacitors are quite interesting how they work. Unlike a variable resistor which might start off at zero and adjust to a maximum and stop. Trimmer capacitors typically do not have stops some of them might but in a watch they do not. The examples below have way more plates than you would have been a watch so basically you have two half round circles. When their maximum together you have your maximum capacitance. When there turned the opposites then you will have the least amount of capacitance. So turning it as you have done may not actually have the desired results. Typically you would have a timing machine for quartz watches and you would turn them very tiny quantities. Then yes even with a trimmer you can get down to a few seconds per day is happy really patient when you're adjusting and you also want to be careful not to press down on them as that tends to bring the plates together and then they have to readjust back to wherever they were plus if you push hard enough you can actually break the capacitor to visit uses ceramic for its construction.

That's interesting thanks - as you might have guessed I've gone the give it half a turn one way, see if it makes things better/worse and try again as I lack the correct testing equipment. What I can say is I think it made things worse so I've turned back and then some more the opposite way... I think I'm going to end up putting the replacement movement in I bought anyway unless I can get it within a couple of seconds a day by pure chance! The other movement without the trimmer remains bang on after 36 hours or so...

[tIB]

And incredibly I seem to have lucked out there - it was no longer four or five seconds fast over last night!