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Discussion Starter #1
Hello,

I am a little stumped at the moment. I'm experiencing a strange problem with one of these early quartz movements, but don't seem to be able to quite pinpoint what the problem is. I figured it was worth gathering opinions before taking it completely apart (again!)

The symptom is that the second hand does not move an equal amount between pulses; sometimes it will move half a register, then catch itself up on the next pulse. It does not do this consistently. Also, sometimes the second hand will exhibit 'shake / backlash, but again, I don't think this is consistent.

The watch has been stripped, fully cleaned and reassembled. I though the problem might be to do with the second wheel jumper that's present on these models, but having adjusted this carefully I think this is OK. When viewed under a microscope the second wheel appears to move cleanly on each pulse and the jumper settles correctly.

So, I'm thinking that the only other thing that could cause this symptom is if the hand itself is loose on its post - it has been removed a few times, but if it were loose I would expect 'slackness' in the hand to show itself consistently.

Also, if there were some form of contamination between wheels and associated pinion leaves, again, I would expect a more consistent problem(?).

Any ideas on other causes for this type of problem would be welcome!

Thankyou!
 

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Discussion Starter #3
Thankyou - will do; I've not methodically been through section J in particular yet, so will report back on how it goes!

Cheers

Andy
 

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Though your problem may lie within the stator A and B relationship, I strongly recommend you do not move the eccentrics controlling those until you have exhausted all other troubleshooting avenues. I've found them rarely to be a problem if they have not been disturbed before- so no need to create an unnecessary problem!
When you look at the seconds jumper again, try increasing the tension a little (rotate the jumper on its axis by pushing outward on the back counterweight area) and see what happens. The magnetic poles on these early quartz calibers were not as strong/precise as later versions, hence the necessity of a seconds jumper. If the tension of the jumper is too light on the wheel, I think you could see intermittent delays/advances with the seconds hand but still keeping time over the long term. Alternatively, a too high a tension could cause loss of time, so watch out for that.
 

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Had the exact same problem with a 7a28 when I first started tinkering. The problem was over oiling and oil in the wrong location. To fix I ended up stripping, cleaning and oiling correctly.
 

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You said you already took it completely apart and all the components were in order ? Could it be that one of the cogs/wheels is missing a tooth or something ?
 

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Discussion Starter #7
Thanks for all the comments! I did another check last night; so far I've left the eccentric(s) alone on the rotor stators, but I did re-mesh the third wheel pinion using the other eccentric on the other side of the movement.

I think the strangest thing about the behaviour of the watch is that after fiddling for a bit, it runs beautifully for a while, but then the strange behaviour returns. I wondered whether it was linked to variances in battery voltage, but have tested it on using both external and battery voltage sources.

I can't help but think it might not be a mechanical / physical issue, but could be one associated with the circuit block. Over-oiling could be a possibility that I'm not ruling out, as could maladjustment of the second jumper but I think the fact that it runs well for a period of time (hours) then decides to start acting strangely might point towards an electronic failure sooner than a mechanical one?

Ideally I'd like to see what happens by swapping the coil block out with a different one; I just don't have one of those at the mo!

It's certainly a head-scratcher. I'd like to post up a video showing the problem; when I've figured how to do it I'll post it up!

Thanks again!
 
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