Document: 990-0000046-1000
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Preliminary
When the electronics has been removed:
1.
Check that all boards are still secured to their mountings.
2.
Check the mating of all connectors
3.
Check that the terminal board screw connections are tight
4.
Check for obvious hot /burn spots by sight and smell.
No Sonar Data
If the sonar display doesn’t scroll, use the ‘scope sniffing’ approach as outlined in Section
7.2.2.1 to check transducer firing. If the transducers are firing, and the data link is working, the
problem is most likely related to the topside processor and/or data modem.
If the display scrolls but is blank and the transducers are firing, the problem most likely lies with
either or a combination of the towfish receiver, transducer or its signal processing circuitry.
Establish if the problem is on a single channel or all channels.
If data is absent in all, or individual channels, check the T/R Switch and SSB boards. If the
problem is with a particular channel, also check the respective power amplifier and transducer
element.
Power Supplies
Several power supplies and voltage regulators are located throughout the towfish assembly. The
main ones are located on the Power Distribution board. The first supply converts the 400VDC
tow cable voltage to the ope48VDC supply. Other DC/DC converters running off the 48
volts generate the low level operating supply voltages. No supplies are adjustable.
The following are the main voltage test points on the Power Distribution board.
Supply Test
Point
Return
+5 VDC +/-0.2V........... TP7 ............ TP12
+12 VDC +/-0.6V........... TP8 ........... TP12
-12 VDC +/-0.6V........... TP9 ............ TP12
+48 VDC +/-2.0V........... TP4 ............. TP5
Other voltages to check on the SSB board and labeled as such are:
Supply
+3.3 VDC +/-0.1
+5 VDC +/-0.2V
+12 VDC +/-0.6V
-12 VDC +/-0.6V
Test Lights
1.
Power Distribution Board
Monitor the +400 volt D4 and +48 volt D8 LED’s. They should be on steady.
