Shearwater Perdix AI Random Dives Caused from Freezing???

[tursiops]

I don't have anything tech-ish planned for at least another few months.

Should warm up by then....

 

[rob.mwpropane]

So I was thinking some more last night. Checked my dc and no new dives. I am guessing the small hole on the back is where the pressure sensor gets its reading from?

I went through how I put stuff away in my head. I (for whatever reason) always place my dc upside down in the case (I guess to save the face), but I leave it 1/2 unzipped to air out if it's wet. So I really think it's ice (THANKS @-JD- !!!). It sits there upside down in the case in my bag and when it freezes causes the pressure sensor to think there's a dive. I wish @ShearwaterJay (that's the only name I could find to Shearwater?) would maybe comment if they've seen this before?

Anyway, I think I'm clear. Pretty interesting, I know lots of people that ice dive but I've never hear of this before.

If Shearwater does email me back I'll post my findings here. At some point I still need to send it in for service, but thankfully I don't think there's any "extra" charges.

 

[-JD-]

So I was thinking some more last night. Checked my dc and no new dives. I am guessing the small hole on the back is where the pressure sensor gets its reading from?

I went through how I put stuff away in my head. I (for whatever reason) always place my dc upside down in the case (I guess to save the face), but I leave it 1/2 unzipped to air out if it's wet. So I really think it's ice (THANKS @-JD- !!!). It sits there upside down in the case in my bag and when it freezes causes the pressure sensor to think there's a dive. I wish @ShearwaterJay (that's the only name I could find to Shearwater?) would maybe comment if they've seen this before?

Anyway, I think I'm clear. Pretty interesting, I know lots of people that ice dive but I've never hear of this before.

If Shearwater does email me back I'll post my findings here. At some point I still need to send it in for service, but thankfully I don't think there's any "extra" charges.

If that is the port, I could see it taking a really long time to dry out, especially in cold and/or humid conditions, as there is probably minimal airflow in a half-unzipped bag in an enclosed space, much-less through a tiny port hole in the DC itself. Even if it was left port-down, surface tension might be stronger than gravity and keep a droplet in there.

Anybody got a dead Perdix and want to do a dissection on it in the name of SB science?!

 

[tursiops]

Anybody got a dead Perdix and want to do a dissection on it in the name of SB science?!

Or, drop a query to DiveTronix.

 

[-JD-]

Looking at the specs in the manual, the sensor/DC is rated for 260M .

None of the phantom dives that you showed exceeded 50M. My gut is that the sensor is probably OK since you were around 1/5th of the max pressure AND it seems to have performed properly after.

There may be a degree of self-limiting: since the hole is open, as the water begins to crystalize into ice there should be some ability for it to escape into/through/out of the hole. a cross section of the sensor chamber would be interesting.

The sensors that I have seen have the piezo element "glued" to a metal diaphragm. If that bond is broken they are done-for.

 

[rob.mwpropane]

If that is the port, I could see it taking a really long time to dry out, especially in cold and/or humid conditions, as there is probably minimal airflow in a half-unzipped bag in an enclosed space, much-less through a tiny port hole in the DC itself. Even if it was left port-down, surface tension might be stronger than gravity and keep a droplet in there.

I agree.

Anybody got a dead Perdix and want to do a dissection on it in the name of SB science?!

Pictures attached might help (I don't remember where I got them, but not mine). I don't have an issue opening up computers and cleaning / fixing stuff, but I have no idea what I'm looking at on a little board like this. The two screws holding the bar down would tell me that hole is the pressure sensor.

If I had the right seals / gaskets and the right torque spec I might even be tempted to "re-seal" it myself.

Or, drop a query to DiveTronix.

Not sure they would be all that helpful in telling people how to take work away from them?

 

[tursiops]

Not sure they would be all that helpful in telling people how to take work away from them?

I was only thinking to ask if the pressure port is that little hole.

 

[lexvil]

Maybe start bringing the electronic inside when it’s that cold outside.

 

[rob.mwpropane]

Looking at the specs in the manual, the sensor/DC is rated for 260M .

None of the phantom dives that you showed exceeded 50M.

There may be a degree of self-limiting: since the hole is open, as the water begins to crystalize into ice there should be some ability for it to escape into/through/out of the hole. a cross section of the sensor chamber would be interesting.

The sensors that I have seen have the piezo element "glued" to a metal diaphragm. If that bond is broken they are done-for.

That was the deepest dive.

Maybe start bringing the electronic inside when it’s that cold outside.

That's at the top of my list!

 

[rob.mwpropane]

Or, drop a query to DiveTronix.

From Richard @ Divetronix (seems like a great guy);

"The depth sensor is located on the backside of the circuit board. If you turn your computer to the honeycomb side, you will see a round hole on the upper right side, under the honeycomb. That hole allows water to reach the depth sensor to register pressure/depth and temperature."

So that would be it.