When something looks wrong, a short list of first checks solves most of it. This lesson covers those checks, the messages the CSH-8L MK2 shows, and its built-in tests.
At a glance
- Every error sounds the audio alarm; R/B silences it
- OVERVOLTAGE: retract and power off
- TRANSDUCER NOT RETRACTED: about 30 seconds
- SYSTEM > TEST holds the diagnostics
About 8 minutes. Part of Own it in the CSH-8L MK2 course.
First checks
- No power: power cable, the ship's mains, the processor fuse, then the transceiver fuse (a technician's job).
- Irregular bottom echo: rough sea or too long a range.
- Weak echoes: raise TX OUTPUT and check the TVG settings.
- Odd colors: check the monitor's brilliance.
- Noise: check grounding, cable separation and INT REJECT.
- Picture does not change with tilt: the tilt mechanism or control line.
Messages
- OVERVOLTAGE: retract the transducer and power off.
- TRANSDUCER NOT RETRACTED: appears if the transducer is not up in about 30 seconds. Cut power to the processor and the supply, then raise it by hand.
- WARNING over 16 knots: shown when you try to lower or raise it too fast; the transducer does not move.
- Over 18 knots with the transducer out: reduce speed and press UP.
- ACTIVATING AUTOMATIC RETRACTION: the sonar reached the AUTO RETRACT speed.
Raising it by hand
Furuno's procedure: turn the hull unit's power off, remove the gear cover, fit the ratchet attachment to the motor gear and turn counter-clockwise to raise it.
Built-in tests
Under SYSTEM > TEST, press EVENT to run a test and MENU to quit. The tests include SINGLE, CONTI, PANEL, COLOR, PATTERN, SIO and ECHO-1 and ECHO-2. SIO ports 1 and 2 always show NG; that is a factory test. ECHO-1 checks the display, where sensitivity rises every 180 degrees. For ECHO-2, set NOISE LIMITER to 0 and horizontal beamwidth to WIDE first; four echoes in a cross is a pass.
Power faults
Furuno publishes a power troubleshooting checklist for technicians. It separates a dead supply from a failed board. One failed supply leaves the LEDs on but disables the hoist and fans, and another looks normal but fails ECHO-2. Leave the isolation work to a technician and give them the symptoms you saw.
Check yourself
Three questions
Sources
- CSH5LMK2 CSH8LMK2 Operator's Manual: Sections 8.6 to 8.8
- CSH8LMK2 Installation Guide: Notes
- CSH8LMK2 Troubleshooting Checklist For Power Issues: Troubleshooting checklist for power issues
This lesson summarizes Furuno's public documents in our own words. Limits and settings differ by model and software version, so your own manual and your installer have the last word. OmniCSH is an independent project, not a Furuno program.