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CM2 Sidescan Sonar User Manual
13. Troubleshooting
13. TROUBLESHOOTING
STR or C-Case will not power up
Check the supply voltage.
Towfish will not start
Wait 30 seconds before trying again.
Check all connectors.
Use a DC voltmeter on pins 1 and 2 of the underwater tow cable connector (disconnected from the towfish)
to check that approximately 42V appears for a period when the towfish is commanded to start.
If an SK172 winch is present, inspect the slip rings within the winch and, if necessary, clean them.
Towfish altimeter locks on to the surface echo
This can only occur if the towfish is nearer to the surface (or the wake bubbles) than to the bottom while, at
the same time, the signal gain has not yet reduced to the correct value for the bottom echo.
Use the towfish bottom-tracking commands to force the indicated altitude to the correct value.
Image contrast poor at the longer ranges
Check that the transducer depression angle is set high (10º).
Check that the transducer faces are clean and free from oil or grease. Clean with mild detergent.
Try greater towfish altitude.
Check system performance in a known environment.
Image shows unexpected patterns on outer zones
If the sea surface is rough and the bottom is smooth then suspect interference from surface echoes. Try
setting the transducer depression angle to low (20º).
Image shows spots or other interference
Temporarily mute the towfish to aid diagnosis, and then try switching off echo sounders, pingers or other
sonars. Also try throttling back any outboard motors, particularly those with underwater exhaust.
Reduce tow speed.
Ensure that the towfish is below the wake.
Try reducing the towfish altitude.
Image shows alternating dark and light bands
If these bands are at 90º to the towfish track, it indicates that the towfish is not flying steadily.
Try to reduce the heave motion being transmitted down the tow cable. Hold a steady course and heading.
Try increasing towing speed so that the vessel holds a straighter course.
Image suddenly goes very erratic
The towfish has probably struck the bottom, or a mid-water obstacle such as an anchor chain, and broken
the breakable washer. Recover the towfish carefully.
Version 3.6 (2008)
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