L3 Comminications SERIES 5000 Operation And Maintenance Manual - page 250
Towfish
D-47
D.8.10 Checking the Multiplexer Board
The Multiplexer board is shown Figure D-22 and performs the following
functions:
• Receives the 200 VDC and telemetry from the surface and
separates out the telemetry from the 200 VDC.
• Routes the 200 VDC to the power supply, and then receives the
converted ±12 VDC.
• Routes the 200 VDC to the Transmitter boards.
• Generates ±5 VDC.
• Generates the time varied gain (TVG) curves for the received
sonar signals from the transducers.
• Multiplexes all the data channels and transmits the telemetry back
to the surface.
• Provides the fiber-optic interface.
200 VDC should be checked across pins 1 and 2 of the tow cable and then checked
from the minus side of C93 and on the U16 side of R59. This will ensure that the
200 VDC is getting to the Transmitter boards.
Figure D-21:
Towfish Electronics Ready for Servicing