Sjöö Sandström Ocean Race Chronograph

[your_man_in_Hamburg]

I have noticed that this watch is not well known, not even to the forum members. Therefore, I have finally got my act together and made some pictures (and info) available to you. (The poor quality is due to the fact that the pictures have been reproduced from printed material, without a scanner.)

Sjöö Sandström folder at mediafire

The watch model was also called Universal Timing Chronograph. I think the production of it has ceased.

Features:

The ability to shut the display off. For fancy dinners, I guess.

Automatic Light Control (ALC). Nothing new, as we know. Just the automated ability to adjust the backlighting intensity to follow the ambient light levels. (I have the impression it was possible to leave this backlight on, but that sounds terribly power hungry.)

The circuitry was developed by the same people in the Swedish defence industry that design electronics for anti-aircraft ammunition. This might give the watch good resistance to knocks and shocks.

PIN-number memory

Audible or silent regatta count-down alarm. When every hand in the crew have their own count-down going, there will be quite a racket on board about at the time the gun will go off. This can be very distracting to the skipper.

Let me know if you encounter any technical difficulties with the pictures. It is the first time I make material public this way.

Your man in Hamburg

[rewolf]

I did know, but only because of your untiring mentioning of it
BTW I think there is another forum member with this watch, so you're not alone

Well, it's rather not my taste (did I ever mention I don't like round watches ?), but it is very interesting for another reason:
If this is correct, then "It has the only digital thermocompensated quartz movement in the world".
And there were "100 ever made"
Here he writes "precision specs ... is +/- 10 sec/year".

[your_man_in_Hamburg]

I have to confess that I don't own one myself. My wrists are to skinny, and I am too careful with my money. I regret both from time to time, mostly the latter.

I promise to stop beating the SS ORC/UTC drum.

Your man in Hamburg

[retroleds]

If this is correct, then "It has the only digital thermocompensated quartz movement in the world"

They must not know about the Pulsar.

[rewolf]

I promise to stop beating the SS ORC/UTC drum.

Please don't - we all beat the drums for our favourites. I hope you did notice the smilies
BTW thanks for putting up this info - another piece added to the "modern LED database"

If this is correct, then "It has the only digital thermocompensated quartz movement in the world"

They must not know about the Pulsar.

True, OMG, how could I forget this thread - so it should read "The only digital thermocompensated quartz movement of the 21st century", or similar.

[retroleds]

Rewolf - I've diligently pried the main chip off a few Pulsars, so all off us will get a chance to look at the thermo-resistor sections(there are 2). A skilled technician can bypass them without removing the trimmer. And I've taken nice shots of the wirebonds on the underside of the chip - pretty cool looking.

I've got both the connections for the early and later(P4) displays all identified - those color diagrams of the relationship of the driver transistors to the segments are interesting, but of no use on a P4 or dress or TC module. A simple tester made from a single LED now allows me to check at the display connection level, instead of prying off transistors and/or displays needlessly. I wish I was an electrical engineer like you, I would have thought of it much sooner.

[rewolf]

Great - can we see these photos and circuit diagrams? PLEEEASE

Oh yes, important rule: don't even try to work on a circuit without a circuit diagram. It's impossible to find errors in a systematic way - just poking about, as you wrote. So if you don't have one, draw it yourself, as you did .
BTW we're a BIT OT now

[retroleds]

Actually, a matter of process of elimination, like chess moves. I'll finalize my drawings during the next day or two. I'm amazed nobody has bothered before.,,,4 commons,7 segments, two probes, specially bent clips for testing the displays "off board".

Hooking an LED to 3 volts is spectacular in the heat produced...before the display melts to crap. Yes, I used a display driver for my work.

We could both stop beating the drum.....the woods would be filled with nothing but the sound of the birds.

[rewolf]

...Hooking an LED to 3 volts is spectacular in the heat produced...before the display melts to crap. Yes, I used a display driver for my work...

3 volts in series with a 1kiloOhm resistor also make a nice display driver for testing .
Still can't hear the birds...

[ronaldheld]

I own one, but have not seen the insides. My watch has not met its spec since I owned it.

[rewolf]

If that spec means 10s/year = 0.3ppm, then it's quite a challenge with a normal 32kHz quartz that has an initial tolerance of usually 20ppm, 10 if you buy a good one. Plus ageing.