Question Problem with Atomic Cobalt 2 Compass

[AndreasR]

Hello together,

I have an issue with my dive computer and I didn’t find any help so far. I changed from cobalt 1 to cobalt 2 device years ago due to multiple problems with the compass. In general the new device “cobalt 2” is perfect and the navigation itself w/o any concern. The problem started days ago when I switched from diving display to navigation display and didn’t see the compass anymore. After diving I tried to reset the computer (pushing left and right buttons for 11s) and I tried to calibrate the compass several times. After successful calibration the compass still was missing (in calibration mode as well as in diving mode). The firmware version 2.500/4 was okay for several dives before and I didn’t find 2.6 yet. I checked compass diagnostic with all “active” measurement values (coordinates…): value for coordinate “AZ” didn’t change while moving the device with different alignment angle. See pictures for details… SW or HW issue? Do you have any advice how to proceed to restore the compass to be displayed again? Anything I could do myself?

Greetings from Germany

Andreas

 

[RonR]

Hi Andreas,
This is a clear case of what we know as “stiction”. The compass is an integrated mechanical-electronic device that is very tiny and requires extreme precision and cleanliness in manufacturing. If, during the chip manufacture, a tiny bit of contamination- even a few molecules- is introduced, it can occasionally cause one axis of the accelerometer to “stick” and become non-responsive. In your case this is the accelerometer Z axis. If the Cobalt’s firmware detects a stuck value, we remove the compass display to alert the diver that the compass is not working properly- on the theory that a missing compass is preferable to one that appears to be reading but is incorrect.

I’d be curious as to the date of manufacture of your Cobalt (the serial # would give this information) as there was a small but unacceptable failure rate with the earliest version of this compass chip, which was in early Cobalt 2's. The chip manufacturer revised their process and we have seen few of these problems in the newer chips.

As to what you can do, often a sharp blow to the cobalt will dislodge the stickiness for a time. It may work properly for a while, as yours has done apparently for years. But the only real fix is to replace that chip on the PCB.

If you are interested in getting this repaired, send me a message here on ScubaBoard and we will discuss how to get it fixed.

-Ron

 

[AndreasR]

Hi Ron,
thanks a lot for your fast and very precise response. I switched to the coordinates and followed your advice. Activation of the frozen value AZ happened just after 2nd little shock (soft hammering on wood)! I performed the calibration of the compass and that’s it: the compass is alive again
I will watch this issue and will let you know if more support is needed.

Best wishes
Andreas