Cobra history confusion

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Jacomo

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So I bought a used Cobra from ebay a couple of months ago. It seems well cared for and everything functions properly, but I have not had a chance to dive with it yet. I was able to get a data cable for it recently and I downloaded DM5. I thought it would be fun to dig through the previous owner's dive profile, plus I figured that if it had any issues with the depth sensor it would be evident on the graph. Nothing looks questionable, but the overall history has baffled me a bit.

The computer shows a total of 208 dives totaling 124 hours, yet only 33 dives totaling 24 hours are shown. Now I get that the oldest dives are overwritten once the memory is full, but isn't the memory supposed to be 36 hours? I thought you couldn't manually delete dives. Even so, it appears that the dives that are missing are not the oldest ones. I show three dives from 2000, then a gap of 14 years and then 30 dives in 2014, 2015, 2016 & 2017. I know dives existed during that gap because the ebay listing showed a few pictures of a printed log (from DM 2.3.0) with my unit's serial number in 2012 & 2013. So how is it that those dives could be overwritten but not dives that were over a decade older?

I also question how 2000 could even be correct because if I'm not mistaken, my unit's serial number (628142) indicates that it wasn't even manufactured until the 28th week of 2006. The other discrepancy I find is those printed dives from 2012-2013 are numbered in the 500's, yet the computer seems to think it has only made 208 dives. I'm stumped. Does anyone with more experience with the Cobra and Dive Manager have any insight that might make this make more sense?
 
I don't know how to direct you to other threads on SB by inserting a link. Maybe someone will chime in and school me but here is my post copy/paste from another thread on Suunto computers...All Suunto computers require an aerodynamic test. This is done by unscrewing the hose from your first stage so you have the console and hose separate from everything else. Next you need to locate a large body of water because there will most likely be a nice breeze. Next step is very important. Grasp the end of the hose and whirl it around as fast as you can and with your timing just right, let it go and watch it fly out into the water never to be seen again. Then buy an other than Suunto computer and dive happily ever after....This bitter flavor recipe stems from a $hit sandwich I recently ate from Suunto on a cobra as well.
 
Maybe I can give a more helpful reply,

The date and year are user set, so it's quite possible that following a battery change there was a mistake in setting the year, corrected after a few dives.

The memory is a nominal 36 hours, but the sample rate is variable using the Suunto software - so if the sample rate has been changed you can end up with much shorter (or longer) total time.

The "dive number" shown in the printed log is also user set, my dive log shows a total of 3406 but my D6i only shows 1089 dives as I had a Mosquito before getting the D6i.

There is one final "surprise" that has happened on my Cobra and my D4i - the total number of dives OR the total number of hours only goes to 999 before starting again at 1.
Looked a little weird until I figured out what had happened!
 
Thank you for the reply, that makes perfect sense. It never even crossed my mind that it could be a result of forgetting to reset the date after battery change. That means that those three dive are likely from 2013 or 2014. Out of curiosity, I just pulled the battery and reinstalled to see what would happen. Sure enough, it defaulted to 1/1/2000 at 6:00 PM. The oldest dive in the memory takes place at 1/1/2000 at 6:03 PM which confirms your theory 100%.
 
https://www.shearwater.com/products/perdix-ai/

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