forum.heinrichsweikamp.com

Hi Forum

My OSTC 2 with firmware 2.97 measures a wrong (too shallow) value for the depth. The deviation gets bigger the deeper I dive. We have compared my OSTC to 2 different dive computers and only mine was off by far:

mine - other
ca. 20m - ca. 22.3m
ca. 30m - ca. 33.5m
ca. 38.4m - ca. 42m
ca. 48.2m - ca. 53m
ca. 58m - ca. 63.5m

A difference of 4 to 5m is IMHO too much, isn't it?

Normally we declare a max depth, e.g. 60m - but since a few dives my buddies are remarking I'm always too deep.

And there is another sign something is wrong: while surfacing, around 1m below the water surface my OSTC shows a warning pp02 of 0.17bar. This happens also for shallow dives (e.g. in rivers).

Today we compared the surface barometer value. Mine shows 875mBar, others have around 940-970mBar - official value was 997mBar.

So, what is wrong with my OSTC? And how can I fix it?
I did a "Reboot", but no "Reset all".


Maybe a dumb question, but I cannot set the custom values anymore on my OSTC 2: Menu > Settings > More... > More...> There are only options for left/right buttons. But I'm sure I've fumbled with the CF values in earlier days directly on the OSTC.

cheerioh
SiS

Hi,

Sorry for the delay. The sensor itself can't be calibrated and an offset is a quite uncommon error. When defective, these sensors usually show values like -99°C and -150m at the surface. Compared to an known good barometric sensor (Do not check your local weather online since they often only show you the "meteorological surface pressure" (Which is normalised to sea level)) you can expect +/- 20mbar of difference.

In some cases massive dirt or salt crystals at the pressure sensor have caused this, so if this might be the case: Remove the backplate (4 screws under the bungee) and check the sensor (It's obvious when you remove the backplate).

I also recommend an update to the 3.07. After update (Or "reboot") the OSTC would re-read the calibration from the sensor. But I doubt that this will make a difference. There are no known errors about the accuracy in the 2.97 or 3.07.

There are no CF in the "new" OSTC (Since 2012 now...) anymore.

regards,
Matthias

Hi Matthias

Please find attached a picture of the sensor. To me it looks clean. Although bought in March 2018 I made only a around 30 dives with this computer.

From working condition (summer 2019) to now (october 2019) with broken sensor I haven't flown, haven't been in salt water and haven't been in mountain lakes, havent beent below 70m. Since I've bought the OSTC in March 2018 I've only made 9 dives in salt water (Lanzarote february 2019).

But now I've got a new issue (see attched):
Maybe around 5 to 10min AFTER I put back on the backplate, the computer started a dive and went stright to 114m! And it stays on 114m! Unfortunately I cannot terminate the "dive" (or can I)? I cannot "reboot" the OSCT (or can I). It is now running since yesterday evening and eventually will run out of battery!

You mentioned something about -99°C - now (after removing and putting back the back plate) I see 99°C. All I did was just as you said: removed 4 screws under the bungees.

Any help is appreciated!
SiS