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6-5
SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION
Towfish is faulty.
Verify the towfish using a
different digital link. Verify the
digital link with a different
towfish.
Table 6-2: STARMUX III Digital Telemetry Link—Troubleshooting Guide
6.3 Towfish Troubleshooting Guide
The towfish is a computer controlled device. Therefore, in order to troubleshoot such a complex piece of
equipment to a sub-module level, one must have the proper test equipment and thorough knowledge of
the unit’s electrical operation plus hardware aspects. The purpose of this section is not to develop those
techniques nor provide a step-by-step procedure where one may start and end up at the point of failure.
It is to give an operator some familiarity with the electronic hardware. The following sections provide
some specific areas to check which are easily identifiable and certain clues as to what to look for in making
an educated guess as to the source of the problem. This is only down to the module or PCB level.
The towfish is a software controlled computer system. There are also some analog sections that interface
with the towfish transducers. Being a digital device, many operating portions use the same data and
address lines a failure of one may result in a failure of all. This makes it very hard to isolate some digital
problems without the proper equipment and a thorough knowledge of the data flow. This equipment is
not normally found on a vessel.
The primary objective is to ascertain which system component is at fault. First, ensure that the system is
properly installed with all connections properly mated. Next, check that the line voltages for the topside
components are within specified limits and any fuses have not blown. Fuses may fail if a wrong connection
has been made during setup. They have also been known to fail for no apparent reason. Always replace
fuses with those of the same value. If a fuse fails again within a short time, there are more serious
problems within the corresponding unit.
Open the cover of the topside electronics and check that all the cards are seated, especially if the unit has
been in transit. After checking the cards, ensure that the cable connectors are properly mated. If the
problem still persists, disengage and then reengage all PC boards and do the same for all board cable
connections, before going on to any electrical testing.
All calibration adjustments are preset at the factory and should not require any modifications in the field
unless certain mechanical and/or electrical components are changed or the adjustments are inadvertently
altered.
If the above checks do not identify or remedy the problem, attempt to isolate the failure to one of the
major system components: the sonar processor, the modem/power unit, the towfish, or the tow cable.
The following presents various operational problems and general comments on where to look and what
to look for.