MkI Running Fast

[charger105]

Hi All.
I have a MkI that is running about 60s a day fast. Is this within the limits of adjustment expected with the trimmer ? Or is a new crystal in order ?

BTW, would it be a clock-wise turn or an anticlockwise turn to slow the watch down ?

Rgds,
Andrew.

[clockace]

i have been turning mine counter-clockwise to slow it down. i have some that do not respond well and am wondering also if a new trimmer would work. i have a 4 reed mkI/II w/o a trimmer that is now down to about 5+ secs/day but when i try to slow it down more the bar segment between the leap yr indication and the secs goes away and it doesn't seem to slow any further. have no idea what to do next. this is the dot segment one i got from howard that was missing the qc. i replaced the qc and cells and sc and it now works well, just can't regulate further. peter

[charger105]

Thanks Peter, I'll try anti-clockwise.
I'm not confident I'll be able to slow it down by 60s a day, but I'll give it a go.

Rgds.

[Higgie]

Andrew, forget it !
A trimmer can only adjust about 3 sec's a day, not 60. And most trimmers are "endless", so you can't say turning it clockwise makes the watch run faster.
Your only option is to replace the QC.

[rewolf]

I agree - 60sec per day is 700ppm, that's too much for adjustment.

But clockace's 5sec per day are possible. If the trimmer is at its end, you can add more capacitance to the oscillator circuit. An additional 10pF capacitor one each side of the QC should suffice. There should be 2 capacitors already on the board, so you can either replace these with larger ones or solder 10pF in parallel of each. No guarantee that this works, maybe the oscillator is already at its limits, but it's worth a try.

Each QC has a "load capacitance" specified, typically 12.5pF for 32.768kHz QCs.
If you replace the QC in a circuit that was desinged for a QC with different load capacitance, it will oscillate (slightly) off frequency. The load capacitance is made of two capacitors, the trimmer being one part of it. A good description is here (PDF) or here (Wikipedia).

[clockace]

rewolf, on my 4 reed module the speed is adjusted using a combo of sliders and the rear switch. it has no trimmer at this stage, altho the solder pads are there on the pc for it. i had a trimmer on it and was trying to adj the time using the trimmer to no real success. then i discovered the directions for adjusting the 4 reed module and subsequently removed the trimmer. the watch continued running so i figured the trimmer was not part of the circuit. and proceeded adjusting according to directions. i now seem to be at the end of the adjustment @ +5-6 secs/day. are you saying i should put the trimmer back in and try again? the trimmer solder pads are on the opposite end of the pc from the qc but i suppose they could still be in the circuit somewhere. if that is so i think i may be able to bring this module into time yet. i was about to give up, 5-6 secs/day is not that important to an old fart like me. i did replace the qc and sc on this one and was thinking if i replaced the qc again i could get one that had a slightly different frequency. they do have a + or - on the 32,768 don't they? is there any way to measure the frequency once it is in the module? peter embarrassed @ my ignorance, but i really like the spell check on the site now.

[Synchroserious]

Yes, changing the QC is definitely the first thing to do in this case.


Like most all Quartz watches made then and years after, there is not much you can do but hit or miss with trimmer adjustments.

That's why my father eliminated the purpose of one 31 years ago.

[Synchroserious]

i concur thas spell chwck is a cool additon But one can reaqlly be dumbfounded trying to reply when there is no reviewing the questions you are attemptng to replying to.So at this point each post should only contain one question That's about all regular emails have an advantage of.

[charger105]

Thank-you gentlemen.
I thought it was a bit hopeful to expect 60s adjustment with the trimmer.

I have no idea what load capacitance the synchronar would present to the QC, but I'm sure any new 32k crystal will get me a lot closer than this current one ! I'll swap it out.

Howard, if you scroll down to the bottom when replying to a post, the original thread can be reviewed, so that you can double-check all the questions ! I'm guilty of asking a lot of questions..........always been inquisitive .

Rgds.

[retroleds]

....one can really be dumbfounded trying to reply when there is no reviewing the questions you are attempting to replying to.So at this point each post should only contain one question That's about all regular emails have an advantage of.

Actually,while posting] if you scroll down below the point where the "Submit" button is, there is a secondary window, which shows the post you are replying to. You can scroll up and down in that window - you can not look at another page.

But you have underscored an issue which makes forum threads ineffective, Howard - posts which only ask one question are better in the long run. For searching and for answering.

And look - we're way off the original question!

[clockace]

update on post about my dot matrix running 5-6 secs/day fast. as suggested on other posts, trying another trimmer or changing the qc, i decided to solder the trimmer back in. without doing anything else after 24hrs it is now only 2 secs fast. now i am going to try adjusting the trimmer to get it closer. . peter

[charger105]

I replaced the QC yesterday, and it's now running about 4s fast per day........a vast improvement on 60s !
It's a shame, I had to dig the old QC out. I like to leave as much of the potting gel in place as possible, to maintain as much of the original robustness as possible. I like the look of the original old rectangular QCs too (not that you'll be able to see it once the module is sealed up).
Anyway, I've tweaked the trimmer 1/4 turn anti-clockwise. Hopefully this will improve on the 4s.

Rgds,
Andrew.

[rewolf]

update on post about my dot matrix running 5-6 secs/day fast. as suggested on other posts, trying another trimmer or changing the qc, i decided to solder the trimmer back in. without doing anything else after 24hrs it is now only 2 secs fast. now i am going to try adjusting the trimmer to get it closer. . peter

The trimmer is normally used to add load capacitance. It always has some "basic" capacitance of perhaps 5pF even if adjusted to minimum. So if you remove the trimmer, there is less load capacitance than expected and the oscillator runs fast or even not at all if there is no other capacitor.

A way to adjust the oscillator without influencing the oscillator could be to measure the LED multiplex frequency. It could be 32.768kHz divided by 512 or 256. But you need a very precise frequency meter for that. And AFAIK the mux frequency is not influenced by the electronic adjustment.

[Synchroserious]

OK thanks Guys.Sometimes i try to answer 2-5 questions from 2-4 different posts.Imagine that task, I would need a secretary for all that

Thanks Rewolf and others for your help with the trimmer questions.

[retroleds]

Anyway, I've tweaked the trimmer 1/4 turn anti-clockwise. Hopefully this will improve on the 4s.Rgds, Andrew.

1/4 turn is a long way to turn it - understand, your trimmer only has an effective range of about 160-170 degrees. Like a single wiper blade on the back of a minivan or such. There is a small dead zone at each end of it's range, beyond which it either starts over as if all the way to the other end of its range or has no function until you turn it 180+ degree to get back to that point. Depends on whether the internal construction is like the single wiper or is more of a double ended blade(like a propeller) . Note - the tubular fine trimmer on a P1-P3 Pulsars(above batteries) is of a different design, which means it's adjustment range covers it being screwed all the way in to almost all the way out.

[charger105]

Thanks Ed.
I assumed it was continuous from min to max over 360deg and then went back to min again.

The machines that detect frequency (by measuring vibrations through the case I presume) would make things a lot easier. I've got a clip on guitar tuner like this ! I notice in the Pulsar manuals, they reference casebacks with a cutaway so you can adjust the trimmer without taking off the caseback.

Without this machine, or a frequency counter, if you are very close to correct frequency, you could be waiting for months to see a second gained or lost.

Rgds,
Andrew.