Sherwood Vision: Air Pressure Failure

[ToneNQ]

Digital pressure gauges display a reading from a piezo transducer. Basically it's a plate that converts the mechanical stress from the air pressure, to a voltage.The precise voltage is proportional to the pressure and that is the value displayed.

It would be been interesting if you connected it to a half full tank, would it have read 5bar? I'd think some sort of grit has got into the line. A few things come to mind.
1. The air pressure reaching the transducer is incorrect due to blockage, or
2. the transducer cannot generate the appropriate stress because it's jammed, or
3. the electronics are not producing the correct voltage from the stress.

It could be a few things, but that is what I'd start with.

 

[divinh]

The HP hose and computer were always connected to the first stage. The fault occurred just before the second dive of the day. How would a blockage have occurred?

That is an interesting test for the computer with half a tank. I'll keep that in mind, but hopefully I'll never have to do it!

One the second dive, I used a spare regulator set.

For the remainder of the trip, I borrowed a spare SPG and connected it to my regulator set.

 

[ToneNQ]

The HP hose and computer were always connected to the first stage. The fault occurred just before the second dive of the day. How would a blockage have occurred?..............

Hard to say, grit in the tank valve of the second tank? It might have gotten pushed into your reg when you turned on the tank valve. The HP port comes off first so that is where debris will often end up.

Cannot be sure, but I have blocked a lot of hydraulic gauges over the years. Very fine capillaries inside high pressure instruments, its not hard to do. That is just a theory that fits your end result, not being there I can't say the real cause of your issue.

 

[NCadiver]

The water hitting the pressure transducer at 3k psi will damage the pressure transducer and if it's saltwater it's worse now you have corrosion as well.

Make sure you dry off the dust cap and the cylinder opening is dry as well.

 

[divinh]

The water hitting the pressure transducer at 3k psi will damage the pressure transducer and if it's saltwater it's worse now you have corrosion as well.

Make sure you dry off the dust cap and the cylinder opening is dry as well.

Unfortunately after all this time, I can't say for sure if there was debris, but in general, things are kept dry and debris free on tank switch overs. Perhaps it was a fluke occurrence.

 

[scubadada]

I've had a number of Oceanic Pro Plus 2s (also a Pelagic Pressure Systems computer) since 2002. They all have quick disconnects. I've never had any trouble with the pressure reading.

 

[divinh]

I've had a number of Oceanic Pro Plus 2s (also a Pelagic Pressure Systems computer) since 2002. They all have quick disconnects. I've never had any trouble with the pressure reading.

I think this is normally the case. With electronics, if something is going to fail, it's usually early on, which seems to be the case with mine.

 

[Mo.Diver]

My Vision won't boot after a battery change. The screen has everything on and it doesn't go off. Would anyone know why by any chance?