[rEvo] Petrel 2 controller intermittently shows 0.0/low PPO2 for all sensors

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

mr_v

Contributor
Messages
617
Reaction score
407
Location
USA
# of dives
None - Not Certified
Howdy folks,

While I was prebreathing, PPO2 shown on the controller/monitor was in the expected range, above the low setpoint. Then, all of the sudden, the controller started showing 0.0 PPO2 across all sensors. Then the controller PPO2 ranged [0.0 - 0.13]. Meanwhile, the solenoid started injecting O2 into the loop. I disassembled the unit, checked all connections, put everything back together - all checked out. The unit was dry, including the battery box. Also, I cleaned the 4-pin connector with DeoxIt suitable for gold plated connectors.

I had a few conservative dives without any issues.

Unfortunately, the same thing happened a few weeks later as I was about to get into a cave. I got out, disassembled the unit and inspected the wire which links 3 O2 sensors (molex) to a 4-pin wet connector. A buddy pointed out that one of the molex connectors was probably damaged. I replaced the connector with a brand new one and did several dives. The problem did not return.

The hypothesis is that moisture got into molex connectors and travled upwire wrecking havoc on voltage readings.

The unit had ~150 hours on it. Petrel 2 has the latest software version. The unit never experienced a flood and I dry it religiously in open air. I still have the supposedly bad connector that I'd like to inspect when I get back home. However, I am curious if anyone else experienced the same issues. If so, what did you discover and what was the solution?

Thank you!
 
When I used to dive/teach rEvo I would occasionally have splitters act this way. Damaged/loose molex connections or moisture in the connections was the culprit as I recall.
 
When I used to dive/teach rEvo I would occasionally have splitters act this way. Damaged/loose molex connections or moisture in the connections was the culprit as I recall.
Jim, did you perform any tests to ensure that the connectors were the root cause? It sounds logical and my fix worked, but I'd like to test the old, broken, connector somehow to double check. I replaced the entire molex-to-4PIN wire just to be sure and have the old one.
 
Probably a bad cable. I've had it happen several times with Fischer cables.
 
When I used to dive/teach rEvo I would occasionally have splitters act this way. Damaged/loose molex connections or moisture in the connections was the culprit as I recall.

Yup @Capt Jim Wyatt is on it.

I don't own a Revo but I have seen and had the same issues with Molex connections (and a splitter seems to make it worse) as have many of my friends this is part of the Molex game. They get moisture or corrosion and start doing funny things. Also sometimes for units that do not have fully potted connections moisture will start to "wick" up your cables from the Molex connection. I now permanently carry extra Molex connections and the special crimping tool in my save a dive tool box.

If you replaced your entire molex to 4pin cable and your not having the issue then I would be pretty confident you solved the problem. As far as testing your old cable I'm not to sure how you would go about doing that. Maybe one of the more electrical savoy members can help you out.
 
Is it possible to do anything to prevent moisture from traveling up the wire from a molex connector? The entire "piggy tail" was $100 - not something I want to replace often... I am ok with replacing a molex connector though.
 
Is it possible to do anything to prevent moisture from traveling up the wire from a molex connector? The entire "piggy tail" was $100 - not something I want to replace often... I am ok with replacing a molex connector though.
Unsure how or if Mares is sealing the end of the cable, but improving your unit to use SMB cells might do the trick.
 
Unsure how or if is sealing the end of the cable, but improving your unit to use SMB cells might do the trick.
Exactly what I did on my home build. Thanks Fathom!

1702349650450.png
 
https://www.shearwater.com/products/swift/

Back
Top Bottom