Troubleshooting the PacIOOS Turbidity Sensor

The SeaBird CTD contributed to the Saipan CREWS station operations by PacIOOS has two add-on sensors for measuring chlorophyll and turbidity.  Since deployment on April 30th, the turbidity readings have been zero.  Gordon Walker of PacIOOS/Hawai`i has been making plans with Steven Johnson of DEQ/Saipan to troubleshoot and fix this problem.

On June 13th, Gordon sent the following email to Steven with and attached photo:

I hope things are going well for you, David and the other folks at DEQ. Mike J mentioned that you will be heading out to the station this week for a monthly maintenance visit. The turbidity reading on the PacIOOS sensor is effectively 0.0000. Can you take a picture of the bulkhead connectors on the PacIOOS sensor (see attached)? Based on how the sensor is oriented, the bulkhead is currently on the "bottom", facing the ocean floor. It has the metal U guard protecting it. The picture should show each connector on the bulkhead as clearly as possible. Thanks.

Click on this photo to see a larger version.

In a followup message that same day Gordon explained that the FLNTUS may be connected to the wrong bulkhead connector (which would be obvious in the kind of photo requested above).  Later Gordon decided that a better diagnosis could be had by removing the PacIOOS CTD from the station and testing its cable:

It looks like the PacIOOS sensor will have to be retrieved on your trip to the station next week. We need to do a continuity check with a multimeter of the cable that connects the FLNTUS to the CTD, and test the bulkhead connector pins with a streaming external voltage check via the CTD. Can we set up a time for us to Skype once you have retrieved the sensor, installed the dummy plug and brought the sensor back to DEQ? Thanks.

Unfortunately these messages weren't received by DEQ in enough time before their June 19th visit to the station for them to follow through on the plans described.  However, plans are being made for further troubleshooting of the PacIOOS turbidity sensor during the monthly July maintenance visit.

[This update posted by Mike Jankulak.]