Oceanic Geo 2.0 Bizarre Behaviour

[diver2005]

I received a replacement Oceanic Geo 2.0 from the Oceanic guys and it behaved really bizarre. When in warm temperature (like a typical warm tropical beach) the DC would stopped working. Then when I was in London this December it just started working perfectly. So basically it started working in cold weather. One day I was sitting next to the heater and it stopped again. Thats when I realised that it doesnt work in warm temperature and works in cold temperatures. Ive searched around and havent seen this being posted by anyone about this kind of a behaviour.

Does anyone know why it would happen?

One possibility could be the change in temperature would affect the battery life? I sent it back to Oceanic and they're going to replace it. I thought would be interesting to post it here and see what people think and to learn why a DC would act like that.

 

[ttbor]

Strange.
I've seen a number of Oceanic Geo 2.0 fail but none fit this description.
In no way am I implying it's a poorly built computer, I'm currently looking into buying one myself.

My limited experience with batteries would imply the opposite effect. Most batteries tend to dislike the cold.

Only thing that comes to mind (other than simply coincidence) to explain the temperature reactions, would be thermal expansion. Potentially a minute amount of moisture expanding to a point where it can short out?

Out of interest, what does "stop working" mean in this case? Turns off?
Interested to hear if the dive shop or Oceanic give you any more info after they handle it.

 

[Belzelbub]

That's actually common with electronics in general. I work in the electronics industry, and a common diag tool to trouble shoot an issue is a can of cold spray. If you've got an open during testing (that should be closed), a shot of cold spray can temporarily fix it so the tech can identify the failing part. Usually it's a more extreme temperature swing, but no reason why a more moderate swing couldn't "fix" the fault.

 

[ttbor]

If you've got an open during testing (that should be closed), a shot of cold spray can temporarily fix it so the tech can identify the failing part.

Not sure I follow, but this is very interesting. Can you elaborate on "an open" ?
Thanks for the insight!
Cheers

 

[Belzelbub]

Not sure I follow, but this is very interesting. Can you elaborate on "an open" ?
Thanks for the insight!
Cheers

I should have put quotes around open. In most cases it's not a hard open, but more of an increased resistance that causes that part of the circuit to not function as it should, or at least read out of tolerance on one of the meters. Usually, the test machine will narrow the fault down to a particular part of the circuit. Then the diag tech would go to work trying to isolate the failing component. Some common methods of identifying the component are cold spray, lifting a lead, etc. It works because copper resistance decreases when cold and increases when hot.

So, I would imagine that in the OPs computer, there is a component or circuit path somewhere with higher than spec'd resistance measurement. When the device is warm, it's high enough to prevent the computer from functioning. When it's cold, the resistance drops enough for it to resume operation.

As I said, it's pretty unusual to see this in the relatively small temperature change the OP is talking about. But theoretically possible.

 

[ttbor]

It works because copper resistance decreases when cold and increases when hot

Learn something new everyday.
Thanks, that makes much more sense to me now.

Guess in these cases the original owner rarely finds out details from the dealer once the item has been returned/replaced

 

[Belzelbub]

Guess in these cases the original owner rarely finds out details from the dealer once the item has been returned/replaced

Most likely, yeah. In a lot of cases, the manufacturer won't even bother getting a root cause analysis beyond the component level. If they start to see a trend, they'll probably dig a little deeper. Otherwise, it's just not cost effective to do a full scale failure analysis.

Of course, that would all depend on the nature of the failure.