Re: adjusting Timex quartz watch

On Mon, 20 Apr 2009 20:51:52 -0400, "Jack Denver"
<nunuvyer@xxxxxxxxxxxx> wrote:


"Frank Adam" <fajp@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:k70qu4hsie19vetll5pm5ll1gu1lpa5plv@xxxxxxxxxx
On Mon, 20 Apr 2009 15:05:14 -0400, "Jack Denver"
<nunuvyer@xxxxxxxxxxxx> wrote:

My timer picks up most ETA circuits running at up to +5 secs/day. Be
it on the 1, 4 or even 10 second gate, this does not change, which one
would expect should, since when timing analogs, we pick up the pulses,
not the crystal itself. And since the pulses are connected to the
seconds hand...hm.. see my problem ? :-)

The problem is in your equipment - unless something is drastically wrong no
quartz watch runs +5 on the wrist - .5 sec is considered the outside
permitted variation.

Equipment is fine, i was shooting from the hip without much thinking.
Ever wished you could pull part of a post back ? :)

Yes, some movements have had the factory adjustments, but i'm not
buying that these are an *intentional fine adjustment* in the factory.
Rather they are necessary ones, so the chips can compensate for the
particular crystal fitted. Crystals are not equal. The cheaper the
crystals, the wider tolerances will shift, which has to be addressed
at the chip. That's my theory and i'm sticking by it. :)


The nature of the fine adjustment feature of the chips is that they can
subtract (skip) cycles but never add, so the circuit is intentionally set up
to resonate slightly fast (this is a function of not just the crystal but
the load capacitor) and then the fine adjustment is added to bring the
effective rate down by skipping cycles . I'm not making this up - this is

I know you're not. I was referring to the chops on the circuit board
though, which has to do with the frequency as prescribed by the quartz
and i don't see that as a fine tune, rather as a required adjustment.

how modern trimmerless movements are designed. I think that somehow your
machine is somehow picking up the unadjusted frequency. Does the tape show
any jitter? As I said before a scope would show this very clearly . I
believe that in some chips the adjustment occurs only 1x/ MINUTE so you'd
have 59 regular (fast) pulse on the stepper and one slow pulse - if the
watch is running 5 sec/day fast, then the one "slow" plus needs to be only
.003 secs slower than the rest .

That explains why i would've missed it, i don't actually time the
watches, just use the thing to check for pulses..

Just doing a test with an ETA 956.112 (Longines actually)
Stuck on the 2 second gate so i can see all changes. It sits on
+5.78-79 with an "o/f" at the 60th cycle. O/f means that the timer
can't decypher the step into any of it's patterns so it pulls it's
display.
That would be the correction cycle then, but it is easily missed,
because a weak or missed pulse will also give the o/f.

--

Regards, Frank
.

Relevant Pages

  • Re: adjusting Timex quartz watch
    ... And since the pulses are connected to the ... Crystals are not equal. ... The nature of the fine adjustment feature of the chips is that they can subtract cycles but never add, so the circuit is intentionally set up to resonate slightly fast and then the fine adjustment is added to bring the effective rate down by skipping cycles. ...
    (alt.horology)
  • Re: Non-chronometer watch with almost quartz precision on wrist? - Why not?
    ... of the crystal, as it vibrates generating an electrical pulse with each tiny movement, and as the circuitry observes the motion, it counts: ... however most of the quartz movements made by the swiss don't adjust the rate via the crystal any more, the crystals are cut to resonate at a higher frequency since they slow down when warmed up, say going from room temperature to body heat, that's what the trimmer used to do, slow the frequency down but cannot be made to speed it up if the native resonance is slower than 32,768Hz. ... anyway the rate is adjusted at the divider circuit level, on the cheap movements, the rate is measured then 1 or more tracks are cut on the circuit board, with this approach it doesn't matter what the crystal oscillates at, one movement could be 32,778Hz, next one 32,796Hz and so on, so long as the pulse being sent to the stepping motor is within tolerance it works fine, and since either the entire circuit board or more likely the whole movement can be swapped, there is no problem in trying to match a new crystal to a circuit should something go wrong down the line. ... dearer movements use a programmable eeprom to store the rate adjustment, these movements also measure the rate a little differently, over each minute or so the frequency is averaged out so then the circuit makes an adjustment to the stepping motor rate, and because of this dynamic rate adjustment you cannot simply just plonk the watch on a frequency counter and trim the rate, they have to be adjusted by a fairly expensive machine that can measure the motor pulse, work out the averaging and then reprogram the eeprom. ...
    (alt.horology)
  • Re: Book recommendation please
    ... From what I understand so far the bias should should not necessarily be the same and the capacitors will not scale as suggested. ... The ESR of the crystal would be different for different overtone crystals so therefore the bias should change to provide correct ... Have they learned by just playing with the circuit in a hit and miss fashion or have they first obtained fundamental information from some text and using what they have learnt then played with the circuit. ... I have surface mountable air fixed coils that provide Q> 100 that I expect should be suitable for most applications and use of trimmer capacitors. ...
    (rec.radio.amateur.homebrew)
  • Re: Book recommendation please
    ... The DC bias would be unchanged. ... In short if the circuit shown uses a 100mhz crystal in a 7th overtone ... crystal and poor quality crystals, If you going to use poor quality ... one working oscillator or flog it to death? ...
    (rec.radio.amateur.homebrew)
  • Re: Book recommendation please
    ... But during his explanation of the butler emitter follower, he mentions the load cannot be "too" small and suggests optimal load of 1/2 to 1 x ESR. ... I realise another option is to build a 3rd OT oscillator followed by ... Also each tank circuit ends up adding lots of cost to the circuit as I usually use a fixed air-wound SMD format coil ... The ESR of the crystal would be different for different overtone crystals so therefore the bias should change to provide correct ...
    (rec.radio.amateur.homebrew)