Urgent help with Uemis SDA

[mintaka]

l've been having issues with my SDA going on "phantom dives" after a plane ride and I thought I had it sorted out. See my earlier thread:

http://www.scubaboard.com/forums/computers-gauges-watches-analyzers/444991-uemis-sda-dead-again.html

At any rate, I am in Jakarta leaving fro Raja Ampat tonight and my SDA is on a 7' dive. It stays on the dive until the rechargeable battery runs down, then shuts off. When I recharge it, it boots up and immediately re-starts at (0 time) a dive at 7' until it runs the battery down. I believe that the pressure sensor has become uncalibrated and sea level pressures trigger a dive. It worked fine last week in a pool in Boulder Co which is at 5000 ft elevation. This morning I took the SDA into the Jakarta hotel pool and at 5 ft deep, it read 12'.

Does anyone have any suggestions ? Thankfully I have a back up computer (no AI) and dive with a mechanical SPG but I am going to miss the AI of the SDA.

I cant remember if the SDA has a gauge mode or not, but if it does and if I could somehow interrupt the phantom dive, at least I could put it in that.

Thanks !

 

[RonR]

You may be right- though it would surprise me if the computer would normally go into a dive with just a few feet of pressure/depth in dry conditions. Particularly since it is altitude compensated and from Switzerland, up in the mountains. Determining the difference between atmospheric pressure changes and actually starting a dive is something all computers have to do. I don't know enough about the specifics of the UEMIS to say if wet contacts are always necessary for a dive or not, but for many computers shorting out water contacts is a necessary precondition for registering a dive. It would be interesting to see if the dive stopped with a slight vacuum- putting it in a plastic bag attached to the inlet of a vacuum cleaner, for instance. The old information I have here doesn't reference a gauge mode.

It does sound as if the absolute pressure sensing is off, though at least it is in the direction of being more conservative. The UEMIS is potted, I believe, it may be picking up extra pressure due to a flaw there. All in all, it sounds as if it's on it's way out.

Ron

 

[mintakax]

Yes, thanks. I was unable to use it in Raja Ampat. I watched it on the two inter-Indonesia flights on the way to the boat and on both flights, the computer "surfaced" but initiated a new dive upon landing. When was in surface mode I tried to put it in gauge mode but it said "previous dive incompleat "
looks like another trip to Switzerland