User guide

FS 20/25 Operators Manual 901-10037001/1.1

Maintenance and Troubleshooting Page 5.11

Kongsberg Simrad Mesotech Ltd.

Port Coquitlam, BC - Canada

Realize that each 3

wire cable is unique. The important thing to know is that if

readings start to vary from your initial recorded values, and you start having

problems with your system, this may be your first indication of a problem with the

cable, pigtail, slip rings, etc.

Any changes in the recorded meter values during normal operation may indicate a

potential problem, even if the unit continues to operate properly. Common causes

are:

• Current Meter Jitters

This is commonly due to dirty, wet or worn winch slip rings that cause current

spikes on the trawl cable when the winch is rotating.

A test for slip ring problems is to slow down the winch (at high winch speeds

you will not see jitter on the current meters) and check if the current meter is

jittering and whether the jitter rate changes with the winch speed.

• Increase in Current

Gradual increases in the trawl unit current may be due to either the trawl

cable or the trawl unit electronics. A higher cable closed loop resistance, due

to cable damage, poor splices, poor winch slip rings or water in the cable,

may reduce the voltage supplied to the sonar head below the required level

for the head connected. This will result in the sonar head drawing more

current. Alternatively, there may be a problem in the sonar head or sensor

module that causes additional current draw.

To diagnose this problem, a current reading should be made with the system

running on the test cable, both with and without the sensor module. If the

current reading, with both the sonar head and sensor module connected, is

higher than a previous value obtained on the test cable, then the problem is

likely with the trawl unit electronics. If the current is higher with both, but the

same as previously measured with only the sonar head, then the sensor

module may be faulty, otherwise the problem is with the sonar head. If the

current readings are the same on the test cable as previously obtained, then

the trawl cable and winch slip rings should be checked.