P4 Dress module way too fast--best way to repair?

[spinchb]

Hi All,

I have a bit of a franken-module from a P4 Dress here. It has small digits, like the ladies. It runs a minute fast a day. It has some extra resistors wired to it. It is not possible to set the days of the month.

I've tried to adjust the trimmer, but it makes no difference to the time keeping. I'm wondering if wiring an oscillator would be the best bet in this instance? The QC is running fine, but fast. An oscillator should bypass the electronics and just go at its own clock rate, should it not? Also, what's with the date? I can set the minutes fine, but no go for setting day of the month. Are these resistors doing something weird with the date setting? Or, holding the whole thing together? Thoughts? Photo link below...

Cheers,
Shawn

https://www.dropbox.com/s/g6pjxm7cshoy2n8/Pulsar-104-P4-dress.jpg

[spinchb]

It was the Quartz Crystal. I didn't realize they could run the wrong frequency like that. I've only experienced flakey ones that run sometimes or dead ones that don't run at all. Seems they can also work perfectly at the wrong frequency. Regarding setting the date, I think I must have been using the wrong button combinations. Seems I forgot how to set one of these. My bad.

It's still an odd module. It looks like it was substantially repaired at some point. The display is quite high off the board and is the wrong one for a P4 Dress, some of the components are a little bit askew and there's the added mystery resistors. It crossed my mind to correct the display on it, but I think I'll leave it as it is. An aberration.

Cheers,
Shawn

[bruce wegmann]

Actually, not so much of an aberration as you might think. This looks like a pretty standard module to me...I've seen the added 15Kohm resistors on a lot of 100-series modules (I'm guessing this was done at the factory, as a repair, to correct some issue with the switches). A final note; the Dress is NOT a P4...it lacks the signature feature of all P4 models...Auto-Command. It's not a P3 or P5, either (the claim that there is, or was, a P5 model has yet to be substantiated; the rare Special Edition Touch-Command Dress models with the Auto-Command feature might conceivably qualify as a P4, but this has never become part of the standard nomenclature). No, the Dress is a kind of "orphan" watch without a "P" designation...it's just a Dress.
As for modules running extraordinarily fast (or slow), it doesn't take as much of a frequency error as you might imagine to make a huge difference in the timekeeping accuracy, due to the relatively low frequency of the timekeeping signals. At 32.768KHz, an error of just 1Hz will translate into a timekeeping error of 2.64 seconds/day, or 963 seconds/year, and 22.7Hz off will create a deviation of a minute a day. The small cylindrical trimmer had a range of + or - 20sec/month, the larger one + or - 60sec/month, just enough to deal with about 100sec/month of error. Timekeeping was normally held to a tolerance of + or - 5sec/month, or roughly 2 parts/million (or .033Hz either way from the nominal crystal frequency). At 1sec/month, that's an error of only 0.0066Hz; not bad for a piece of commercial 1970's electronic technology. I've seen a few P2 and P3 modules that were still running even though my quartz monitor will only read an error of 200sec/month (6.4sec/day)...after that it just tells me it's "overrange", so I can't say with certainty how far the quartz can drift before it just quits oscillating.

[spinchb]

Thanks Bruce, quite interesting, as usual. This Dress model is almost ready to go on my wrist, keeping time and looking fine. It's in really good shape too. I like the Dress model quite a bit so I'm glad it found me. I have one problem with it though, the band is too big for my little wrist. I have to put another band on it to wear it, which is a bummer. The original looks great. If watches were to be worn around the waist, I could grow into it.

Cheers,
Shawn

[bruce wegmann]

It's worth noting that a P3 leather strap is an exact fit to the Dress case lugs, so, if you don't mind wearing leather, that would be a very workable solution to the size problem; the leather straps had a much greater range of adjustability over the metal bracelets.