Document: 990-0000046-1000
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Monitor the data link light. There should be
one on the topside and towfish modem cards.
Some topside processors have an indicator on
their front panels. The light will flash initially
at power turn on, but then remain steady on.
If the light remains flashing for more than 3
minutes, replace the modem card(s). If it
doesn’t turn on, or has random flickering
check
the tow cable connections and cable-select
jumper.
Another source of an erratic link up is the AC
ground between the electronics ground and
the towfish housing. Check that the
grounding capacitor located on the rear end
cap is not open
Listen for a smooth sequence of rising tone
bursts after boot up.
If the tones are erratic, check the CPU and
Modem boards.
Verify that the link up is steady.
Cable and its terminations,
Towfish Modem and Power PCBs.
Check for a transmit signal emanating from
each transducer element using a scope sniffer.
See Section 7.2.2.1
•
If only one side is transmitting,
Towfish port or starboard transducer or their
connections,
Towfish port or starboard transmitter PCBs
Sonar Interface Board (SIB)
T/R Switch board
•
If only one element is not transmitting,
Check the element connection on the rear
bulkhead
Check for 48VDC across J2 of the Power
Amp associated with that particular element
Check the Power Amp associated with that
particular element
Replace the transducer element
•
If all element are not transmitting,
Check the +48VDC power at the power-
distribution terminal board TB1 located
adjacent to the starboard power amps.
Sonar Interface Board (SIB)
T/R Switch board
Change towfish range. Note that the
transducer firing changes accordingly as the
range changes.
Check the CPU card if transmission rate
doesn’t change with range.
