Another quartz module challenge

[HectorLooi]

I like to get the opinions of our two best minds on quartz electronics. 

This a video taken by my mentor. It's a Cartier 81 movement with the entire gear train removed, with just the rotor in place. It's a 2 hand movement with a pulse every 10 seconds. The hands were not moving, only a microscopic stutter every 10 seconds. 

So what do you think is the fault? Electronics? Rotor?

(BTW, he fixed it and you wouldn't believe the culprit part.)

[LittleWatchShop]

1 hour ago, JohnR725 said:

I keep hoping that you would say yes I would love to do my experiments but I don't have any movements?

Sometime after the middle of the Summer, I will have more time to do such experiments.  So many projects are stacking up that are not getting my attention...meanwhile clients are pounding at the door.  It won't last forever.

[LittleWatchShop]

1 hour ago, HectorLooi said:

So what do you think is the fault? Electronics? Rotor?

So what are the candidates:

Battery, battery contacts, connection to the coil, the coil. the IC, power to the IC., the rotor, the stator.

What we know.  He fixed it.

Since he fixed it (guessing not a full module replacement), so we have to look at things he could fix.

That would be everything but the IC.

I will hazard a guess that the problem was the connection from the battery to the coil.  Maybe a previous failed battery caused some corrosion in the series path and the resistance increased just enough to cause failure.  I had this problem with a Seiko movement...turned out to be a trivial fix.  Corrosion eats away copper traces.

That is my guess (SWAG).

[JohnR725]

I do notice a minor problem with the video though yes it does appear to move but we really need to have one of the teeth colored marked or something so we can see if it actually is rotating.

then there's the other little confusion here wasn't this at the tail end of another discussion did somebody move it? The problem was the other discussion was a different quartz watch we really need a picture of this quartz watch we need to start from the beginning.

then background history would be nice.

6 hours ago, HectorLooi said:

(BTW, he fixed it and you wouldn't believe the culprit part.)

as you want us to guess the problem but you're showing us a video in the video should really be helpful for indicating what the problem is.

 

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Cartier_81

http://www.ofrei.com/page1113.html

http://www.phfactor.net/wtf/Frederic Piguet Tech Sheets/330_fp820.pdf

 

 

 

 

[HectorLooi]

Hmmm... yes. My post seem to have been moved.

This was a watch which my mentor was repairing. The watch hands were not moving after a new battery was fitted by another watch repairer. That repairer quoted $1000 for the repair.

My mentor found that there was a pulse every 10 seconds and the gear train appeared ok with the line release test. He ordered and fitted a new pcb but still it was a no go. Next, he did a full disassembly, clean and oil. But still no go.

I suggested that it could be a weak rotor, as I was struggling with a movement at that time that appeared to have a weak rotor. ( I start another thread about this watch later)

My mentor said that he has never heard of a weak rotor. Anyway, he went back to basics and swapped component by component until he found the problem. (Drive train components, not electronic components)

The problem was..... a weak coil!

[JohnR725]

7 minutes ago, HectorLooi said:

he problem was..... a weak coil!

I went back and looked at the PDF that I had up above interesting there is no coil resistance?

I've seen something similar before. I used to do warranty work for a company quartz watches all identical. Incoming I like the separate them dead watches versus potentially running watches. The dead watches then I run across a timing machine to pick up the magnetic impulse just to make sure they really were dead. Usually fully dead watches were battery changes. but it's always interesting you usually remember the really strange things. So I had a watch I had impulse everything seemed to be fine it was a long time ago as I don't read the details but I change the circuit with the coil the watch ran it? Might not have been a bad coil are weak coil it might've been a week output from the integrated circuit but it still possible the coils can intradermally short out they can also get shorted out of someone's not careful and scratches or pokes them. A lot of times the open up but sometimes they may not conceivably.

 

9 minutes ago, HectorLooi said:

never heard of a weak rotor.

then unfortunately this is watch repair everything is possible just sometimes extremely unlikely.

[Graziano]

25 minutes ago, JohnR725 said:

this is watch repair everything is possible just sometimes extremely unlikely

I can feel a headache comin' on

[LittleWatchShop]

4 hours ago, HectorLooi said:

a weak coil!

I am struggling with this.

The only thing that would weaken the coil would be shorted turns.  I suppose that is possible but unlikely except in the case of poking or scratching it as john said.

An alternative view would be that the contacts to the coil were at fault and the process of replacing the coil resolved the contact issue.

Edited April 24, 2021 by LittleWatchShop

[JohnR725]

2 hours ago, LittleWatchShop said:

The only thing that would weaken the coil would be shorted turns.  I suppose that is possible but unlikely except in the case of poking or scratching it as john said.

An alternative view would be that the contacts to the coil were at fault and the process of replacing the coil resolved the contact issue.

if the original coil is still in existence perhaps a visual assessment of its condition would be nice? Like where the contacts are made do they look like there's corrosion? Physically does the coil look like it's been scratched or poked. Sometimes that's really really hard to see it might even just look like a shiny spot. Then the coil resistance but that's not always a clear indication. If the coils been shorted by a few turns resistance probably won't show that. The other thing important to do with coils but usually not done you're supposed to check from one lead the frame or basically the ground. That used always be mentioned as a separate test so if the watch companies wanted you to do it there was a concern that the wire which short to the ground.

But are still stuck with interesting problem coil is replaced problem is fixed.

Oh one other thought that would've been interesting which is current consumption I wonder if that changed?

[jerryvs]

some battery changers here not watchmakers push the back cover very hard 

and the cover hit the battery or have a contact for this movement I'm putting on some kind of insulation.

between the back cover and the battery