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Novus with a fast running module.

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Led-Time

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Novus with a fast running module.

Post28 Feb 2006, 20:43

Hello Guys,

I have a Novus LED which runs fast I would like to adjust the time keeping, I know this is set with the small potentiometer inside. I have access to a calibrated frequency counter at work so I took the fast running module along with a good time keeping module to compare the readings.

Here?s the problem, the good time keeper reads 32,767Hz which is OK and the fast runner reads 32,777Hz which is what I expected but when I put a slight turn on the adjuster (which should have moved the quartz frequency either side of 32,777Hz) it makes no difference to the reading. No matter how much I turned the little screw the reading stayed the same at 32,777Hz.

The readings were taken from both sides of the quartz with the probe earth clip connected to the negative side of the module.

I don?t know why the readings won?t change does anyone have any thoughts or comments.

Thanks in advance...
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Re: Novus with a fast running module.

Post28 Feb 2006, 21:04

Sounds like the variable capacitor (the adjustment device) is no longer working, over time the dielectric between the plates deteriorates and the capacitor is no longer. Try one taken from a non-working led, or a new one, the value should be 30pf (pico-farads) if buying new.
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Re: Novus with a fast running module.

Post28 Feb 2006, 23:48

9 Hz is a lot, probably a new trimmer won't work because it is still out of range. You can try a trimmer with a slightly higher capacity and if this still doesn't work you probably have to chance the crystal also.
The higher the capacity of the capacitor, the slower the watch will run, but a high capacity also makes the watch less reliable in time keeping because capacitors are more temperature sensitive.

A test i did last year, every test was was done in a 48 hours period with a cheap Hong Kong 70's lcd watch. The watch was not waterresist and was full of ice in my freezer, i hope this didn't influence the values...

Watch without capacitor:
25 C +2 seconds
7 C +1 seconds
-20 C -5 seconds

The same watch with capacitor:
25 C 0 seconds
7 C -1.5 seconds
-20 C -9 Seconds

Note: the range without capacitor is 7 seconds, with capacitor is 9 seconds.
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Re: Novus with a fast running module.

Post01 Mar 2006, 01:20

NSC modules are great but their quartz crystals are junk. When they start to go, the trim caps do nothing. I have to replace the QC's on these all the time and I just did a replacement for someone, yesterday. Now it's running 2 seconds fast a month.

MJ
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Re: Novus with a fast running module.

Post01 Mar 2006, 17:32

Klippie: If you are running a frequency count on the crystal per se, you will NEVER see a difference in the frequency of the crystal...the trimmer compensates for variation in the quartz crystal frequency, IT DOESN'T CHANGE the frequency generated by the crystal(yelling for emphasis, not to be a prick) - you have to be sure to properly check the crystal post trimmer. Try adjusting the trimmer(or checking it for life before proceeding),remembering that the trimmer never needs to be swung through more than 180 degree....the next 180 is the exact same thing and risks damaging it, though sometimes a few swipes back and forth will bring the contacts back into play by essentially cleaning the contacts. Just tweak it back, and check your time. Realistically, 10 hz in the crystal is almost inconsequential. THIS is the kind of thing that a knowledgable member of this forum should have just spoke up on right away. :shock:

IMHO:Gentlemen(and ladies if we have any),evangelize to inspire the craft...you won't need your watches beyond this plane of existance, no matter WHERE you think you are going. 8)
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Re: Novus with a fast running module.

Post01 Mar 2006, 17:59

The readings were taken from both sides of the quartz with the probe earth clip connected to the negative side of the module.


Wrong way to check this....refer to my earlier post on this for some clarity; albiet not all details to finessing this
problem
. Have to admit, I think worrying about anything less than 30 seconds a month is a little neurotic....depending on module you may have to change settings 5-7 times a year, just to compensate for days in month. Discussing those missing seconds seems like a form of "mine is big/badder/better" bragiddacio[sic] aimed at discouraging those whose treasured timepieces don't "measure up". :? If it keeps time within 1 minute a month,be happy!!

Back in the 70's a popluar song asked,"Does anybody really know what time it is, does anybody REALLY care?"[/quote]
Last edited by retroleds on 01 Mar 2006, 22:29, edited 1 time in total.
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Re: Novus with a fast running module.

Post01 Mar 2006, 18:28

little1up wrote:...Realistically, 10 hz in the crystal is almost inconsequential....
I don't want to look like a nitpicker here, but 10Hz off is 26 sec/day, 13minutes/month.
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Re: Novus with a fast running module.

Post01 Mar 2006, 19:35

kateshitikano - I stand corrected on the amount of time at issue...that IS enough to be distressing. Guess I "fast fingered" that one because I get kind of tired of people bitching over the ones that only lose a minute every few months, when they have to set them anyway.

Adjust the trimmer Klippie or send me a picture and I'll send you another module dirt cheap if I have one. The dog says I am full of it.
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Re: Novus with a fast running module.

Post02 Mar 2006, 14:33

little1up wrote:...because I get kind of tired of people bitching over the ones that only lose a minute every few months, when they have to set them anyway...
Yeah, I remember trimming my Casio Telememo to 1 sec/month. It took me 10 adjustment interations and several months until I was satisfied. I was 13 or 14 years old...
Today, some of my favourite digitals (modern LCDs) can't even display seconds. When it's more than one minute off I might start to think about setting it. I see this as a positive attitude change :wink:.
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Re: Novus with a fast running module.

Post02 Mar 2006, 14:47

I figure if it runs a minute fast a month,set it one minute slow and after a month it will be dead on, and a month later it will be one minute fast. :lol: Right about then there will be a month that isn't 31 days and you will probably have to reset anyway(obviously depending on the module). I worry/wonder about how many people ruin a perfectly good module by tinkering with it needlessly(in my opinion). They are an old collectible - aren't they suppossed to be a little odd in their behaviour!? :lol: I'll be the first to admit that a watch worn for daily,personal use that is off by more than 1-2 minutes a month is aggravating...if only because people tell you your watch is set a bit off. My wife constantly tells me the clock in my car is wrong. She's right, that piece of crap loses 2 minutes a month. :?
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Re: Novus with a fast running module.

Post02 Mar 2006, 15:20

little1up wrote:I figure if it runs a minute fast a month,set it one minute slow and after a month it will be dead on, and a month later it will be one minute fast
That's exactly what I try do to. Unfortunately, to do it right, it requires keeping records (or a good memory) of which watch is how much fast or slow, so we are basically back where we started...
little1up wrote:My wife constantly tells me the clock in my car is wrong. She's right, that piece of crap loses 2 minutes a month. :?
I agree - a watch that cost probably some 10,000$ (ok, including the seats to sit down watching it, and some other protective stuff around it) ought to be more accurate :wink:
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Re: Novus with a fast running module.

Post03 Mar 2006, 01:34

Thanks everyone for the quick replies and info,

I'am keen to get this module back to some sort of accuracy if this means replacing the quartz and the trimming capacitor so be it.

I checked out Maplins website for suitable components a 30pf variable capacitor as recommended by ?led watch? and a 32,768Hz quartz crystal, I found these items?
http://www.maplin.co.uk/Search.aspx?criteria=Miniature%20FilmDielectric%20Trimmers&doy=2m3&source=15
http://www.maplin.co.uk/Search.aspx?criteria=Timing%20Crystals&doy=2m3&source=15

Will they be up to the job or does anyone have a preferred supplier for the above components.

little1up,
I?am a bit confused regarding your description of how the trimming capacitor regulates the quartz crystal, you mention the trimmer doesn?t change the actual frequency of the quartz so for accurate time keeping. Lets say the crystal should run at 32,768Hz any deviation either side of this figure will show the module gaining or losing time. How then does the trimmer alter the time keeping if it doesn?t make the crystal run faster or slower to bring the frequency back into place for accurate time.

Here is a picture of the module showing the points where I took the readings with the frequency counter, these points were the only places I could find which gave the figure of 32,777Hz...

Image

If I have used the wrong connections would someone please show me where the correct points are to take the readings.

Thanks...

Klippie.
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Re: Novus with a fast running module.

Post03 Mar 2006, 07:42

I know that modern quartz crystals are more accurate when new than the crystals from the 1970's. What would happen if you simply removed the trimmer and bridged a wire across the contacts and then installed a new crystal?
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Re: Novus with a fast running module.

Post03 Mar 2006, 08:14

I've replaced a ton of modules with modern day 32,768Hz quartz crystals and only once did I have to replace the trimmer and in many cases I don't even have to adjust the trimmer because the QC is so tight in its timing.
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Re: Novus with a fast running module.

Post03 Mar 2006, 11:32

HDLED wrote:...What would happen if you simply removed the trimmer and bridged a wire across the contacts and then installed a new crystal?
It won't work if you bridge the contacts (you could even damage the oscillator circuit). Better leave it open (probably won't work either) or install a fixed capacitor of, say, 22 or 27pF.
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Re: Novus with a fast running module.

Post04 Mar 2006, 19:32

Klippie - leftmost contact point you indicate, and the "intake" end of the trimmer, right the one that bridges to the "+". That way you are getting the effect of the trimmer being a series portion of the crystal/trimmer interaction. Your pictured contact points are showing "post-trimmer". There is an assumption being made here on the crystal leads...can't see under it from here. The trimmer modifies what naturally occurs in the crystal....just sort of throttles it a bit.
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Re: Novus with a fast running module.

Post07 Mar 2006, 02:35

I bought a new quartz crystal (nearly broke the bank at 37p) over the weekend and replaced the NS original in the module.

At work today I got hold of the frequency counter and trimmed the new quartz to exactly 32,768Hz which should now keep very good time. I?am over the moon now its working as it should.

Thanks to everyone who came forward with the information you have all helped to bring one of my favourite watches back into specification.

Cheer's...

Klippie

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