Cobalt 2 Screen Goes Black

[JFish180]

Hi,

I have been dealing with intermittent problems with my Cobalt 2 for the last few years... The problem has popped up four times over approximately 40 dives and occurs sometime after I have completed a dive but before starting my second or third dive.

The most recent occurrence happened after my second dive this Friday. I was clicking down to check my last dive log and the screen went blank. I tried to manual reset by holding down the select and back buttons, but the computer remained blacked out. Fortunately I have a backup computer and spg, so I was able to go on my third dive. I was hoping that the computer would wake up when I hit the water, but it did not. After the computer sat overnight, I checked it this morning and it is working fine now... Battery is at 35% and even though the display was not working, my Cobalt 2 logged the whole third dive.
The last time I had this problem was about 15 or 20 dives ago. After the last time, I updated firmware and also paid to have Huish Outdoors do a full diagnostic. They found no problems. Any help you can provide would be greatly appreciated.

Thanks,

Jared

 

[RonR]

Hi Jared,

What is the age and serial # of the Cobalt? That helps me know which build it represents. And also if it is still under warranty.

From what you say my first guess would be an intermittent issue with the display connector or the display. The fact that it logged your dive correctly shows that the computer is working, but just not turning on the display. Without opening the Cobalt it's difficult to say if it's an intermittent connector issue or the display itself. Another possibility is that a backlight controller is getting out of synch- that is something that could happen only with a part that was used in very early Cobalt 2's. Knowing your serial # would help to see if that is a possibility.

Do you know if Atomic replaced the display when you sent it in? That would certainly be one of the first things to look at based on your description. But let me know the serial # and we will go from there.

Ron

 

[JFish180]

Hi Ron,

Thank you for your reply. My Cobalt 2 SN is 3814-0504. Version is 2.460/2. I think I bought it about 3 or 4 years ago. Took it to have a full check up about 2 years ago and they couldn’t find any issues. Also, I’ve only seen this problem pop up between dives, so not sure if there is a specific sequence of events that causes it or if there is a tiny leak somewhere causing a short? Again, Atomic/Huish couldn’t find anything wrong with it when it took it in..

 

[RonR]

I don't think this indicates a leak, if the computer were shutting down your third dive would not have been recorded. And the fact that you have seen this intermittently over time without the Cobalt failing would indicate that the problem is limited to the display.

My primary suspicion is the backlight controller. A couple of questions to help with further diagnostics:

1. When you say you were clicking down to look at the log, what screen were you in?
2. Did you see the brightness changing at that time, as you were clicking?
3. Or did you have the screen brightness in "auto" mode?
4. Is the time of the third dive correct? If the Cobalt had restarted with the Back-Select button press, the time would have reset to the end of the last dive. If the time didn't change that would indicate that a reset did not actually happen.

There is an issue we have seen with a very few Cobalt 2's from that first build when the backlight controller gets out of synch due to a timing problem. This can cause the screen to appear black. Typically a sleep/ wake cycle will reset the controller and fix the issue. Is that consistent with what you have seen in the past? One customer even improvised a workaround where he pressed the Back button enough times to know he was in the Main Menu, then pressed Down 5 times to get to the manual sleep mode, then Select twice to put the Cobalt to sleep, and again to wake. In late 2014 we changed to a different controller chip that can't have this issue, but from the serial # it seems you would have the earlier part.

Let's try to confirm if this is the issue- questions above will help- or something else related to the display, and I should be able to give you some options.

Ron

 

[JFish180]

1. I was in the Main Menu when it went dark
2/3. I didn’t notice any screen brightness change, but not totally sure.
4. Yes, the time for the third dive is correct. The next day, though, the computer had reset and was asking for Date and Time to be set.

 

[RonR]

Just to be clear on #4, the Cobalt reset on its own, without your pressing the buttons?

 

[JFish180]

Well, I tried resetting before the third dive, but it didn’t work. It seems to have reset on its own sometime after third dive and the next day.

 

[RonR]

The spontaneous resetting is a concern. That would indicate something else, other than just a display issue. If you are in the dive screen, does pressing the down button toggle through screen brightness levels as it should?

 

[JFish180]

Yes, from the dive screen, pressing the down button does change the brightness levels. Brightness keeps lowering until it re-starts at maximum...