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Longines VHP accuracy

40085 Views 122 Replies 14 Participants Last post by  ronalddheld
Fellow watch nerds!

I have a Longines Conquest VHP watch that runs too fast. Faster than the 10 seconds per year that Longines advertises with. My watch gains 5 seconds per month. Almost a minute per year.
I have been keeping an eye on it, for a few months now, and it is very consistent at gaining one second every 6.5 days.

It might be due for a new battery since it is almost 8 years old. The second sweep still moves every second though.

It has been quite good so far, although I have not paid it as much attention before. I think it used to be one or two seconds out per month.

Anyone else has experiences with a VHP? I read that the rate can be adjusted when serviced. Is that a good idea? Who could do that?

It is a 1999 Conquest Perpetual Calendar Calibre 546. It has 'L1.632.4' inscribed on the back. Not too sure what that stands for.

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Well, I did some more corrections and I can confirm 'tapping' on the correction patches is the way to go. As indeed is outlined in post 41 by Ppaulusz.

Hold the correction wire too long on the patch, and you run the risk of registering more than one correction impulse. That is for me the only explanation as to why I over-corrected in my first attempt.

I tapped the 'faster' patch 10 times, and the watch is now within the 0.8 sec per month spec. It is going so well, that my video recordings give no early indication of the yearly rate anymore. Apart from that it's a lot better.

I would like to see one more step after step 4. 'Wait for the date ring to complete its turn.'

heqphoria here I come!
Getting closer...
I figured it could do with another single correction.

After three weeks of measurements, and realizing that I was dealing with some serious measurement noise here, Mr S.Tochastic advised me that the rate was 0.338 seconds per month slow.
One correction impulse of 0.33 sec/month would fit nicely here.

Here are the measurements.
X-axis is in hours after the regulation. Y-axis is in seconds fast/slow.


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It's just that I can't stand waiting for a month or three to get my one second difference.
And then find out that I've made another mistake somewhere and have to to it all over again.

Would be interesting to see what would be a good method for rate calculation without a laser and two atom clocks. Start a thread for that?
Very clever!
Now why didn't I think of that?
Simple ways to solve a complex problem. I like it!

Tapping on the golden conductive part is the way to register impulses.
A quick tap is enough.
A scrape could register a few impulses.

The lack of feedback is the main problem here:
No clicks, no beeps, no movement.
The effect of on impulse is only seen a few weeks later.

That's why I had to make my own timing machine. So that I could quickly see what I had done.

I easily made more than a dozen attempts to get anywhere near the perfect setting. Then I made a dozen more for no good reason, simply because I did not account for temperature effects.

The watch can stand it. It won't break because of it.

On the other hand: Try to get a perfect result with a condenser screw.
They are way more finicky.
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I stopped calibrating when it was at 2-3 s/yr off while (mostly) wearing.
If I wear it continuously it gains 10 ms per day.
A cold night off the wrist slows it down by 15 ms.
A warm night slows it down by 5-10 ms.

So setting it to a slight gain leaves you some room to take it off now and then.
And leaves you some room to 'cheat'.

I have never seen an EOL signal. But there's still time.
@Hans - how do you measure milliseconds with your video setup ?
Well done!
Don't give up.

Quite right. Anything under 40 ms is not visible with the video method.
Video frame analysis is a good way to start.

Now I measure stepper motor pulses.
Down to hundredths of milliseconds now...

My fist attempts are still available in some old threads:
Well done both of you!
Some good tricks there.
The shirt button and starting off with a date of one.
Almost makes me want to do it again.

Needles, buttons, what's next?
Transparent buttons would be even better.
If we have to believe the high aging numbers, another calibration is due any minute!
Good news, my Aerospace went back to normal after I changed the battery (tiny screws, not easy!). Still interested in the steps if anyone figured them out.

I'm sure I saw another post of yours recently were you gave the time in spy...but can't find it again, even after a good hour of searching! Anyway I was wondering if you'd seen any changes in the drift over time (the so-called "aging") with your elaborate setup? It must be there since many of the TC watches that fall into the hands of the crazy bunch here are often way out of spec.
It is measured every day and when its too far ahead I leave it off overnight to slow it down a bit. That way it stays around 10 ms from perfect.
That way I can't keep track of the rate though.

If there was any aging I would only notice that if I mostly needed to leave it off overnight or something like that. Nothing like that has happened so far. The temperature effects are far too large to notice the tiny aging if in fact it did exist.

It really needs a very elaborate temperature setup like dwjquest's one to ensure you measure in the same environment from one year to the next.

As in: one needs to be ridiculously sure that the 22.0 degrees now is the 22.0 degrees you had last year.
That is quite a challenge to get right. I guess I'd rather let dwjquest do the hard work!
Nice strategy! Maybe you can't keep track of the rate "scientifically" but it does show that there is no significant impact of "aging" plus at the end of the day what matters is the "real life" ;-) Still I wonder how all these TC ETAs got to be so much out of spec in terms of their drift at 50+ spy.
The quartz literature all mention aging. But the aging stabilizes to a constant rate after certain period. I guess the movement must compensate for that constant rate.

With these quoted values being so high, its effect should have shown in the watch performance already.

Personally I put the bad initial performance down to the lack of calibration. Looks to me like that step was left out altogether. :think:
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