User guide

FS 20/25 Operators Manual 901-10037001/1.1
Maintenance and Troubleshooting Page 5.2
5
Kongsberg Simrad Mesotech Ltd.
Port Coquitlam, BC - Canada
5.5.3.5 Full 3
rd
Wire Assembly (Including Slip Rings and Wheelhouse Cable)
The absolutely weakest link in the entire FS Trawl Fishing System is the 3
rd
Wire
Pigtail Connection. If the female inserts have been contaminated with salt water
and start to corrode, they will cause the 2-pin connector pins of the attached head to
corrode and/or “burn”. You will start to get telemetry failures, erratic head behavior
and ultimately the system will fail! It is essential that regular, routine maintenance is
performed on the 3
rd
wire pigtail.
The second weak link is the section of the cable that could and does experience a
snap-loading effect when the trawl is deployed.
The third weak link is the slip rings. If they are dirty or corroded, you will experience
telemetry errors as described in previous sections. They can also mean that we are
trying to diagnose problems in the wrong area of the system (problems with heads
that don’t exist).
The following sections offer some tips in trying to localize problems to a specific area
of the 3
rd
wire assembly.
• Testing Trawl Cable
If, after testing the FS system, the trawl cable is suspected to be faulty, then it needs
to be investigated to determine what and where the problem is. For problems that
are not obvious, however, this can be quite difficult to do and may require someone
experienced with testing trawl cables. This section provides some basic tips in
troubleshooting a trawl cable, but is in no way a complete and comprehensive guide.
• Cable Impedance
The use of a Meggar to check the impedance of the trawl cable may be the most
useful test. It can be done with or without the slip rings connected, and readings
should be taken between the cable’s two conductors and also from each conductor
to the fishing vessel hull. As a minimum, the impedance should be greater than 2
Mohms, and preferably over 6 Mohms.
Caution!
The FS system MUST be disconnected from trawl cable during
Meggar tests to prevent possible damage to the electronics!