D-40 APPENDIX D General Setup, Configuration and TroubleshootingSeries 5000 Sonar System Operations and Maintenance Manual P/N 11210060, Rev. 13.0D.8.1 Testing the TowfishThe towfish block diagram is shown in Figure D-13.D.8.2 Checking the Telemetry Link to the TowfishTurn the TPU on and check the LOCK LOSS and ERROR lights. The lightsshould be off. If they are on or flickering, there is a problem. Again, a telemetrylink problem could be one or more of the following: towfish fuse failure, cableassembly problems, miswire, open, using too long a cable, using wrong type ofcable, or a failure in the towfish.Figure D-12: Towfish with Bathymetry Transducer ConfigurationFigure D-13: Towfish Block Diagram