DS35 User Manual
15
8 Troubleshooting
8.1 Technical Description
The transmitter generates pulses (201 kHz) of ultrasonic energy, radiated towards the bottom of the sea.
At exactly the moment a pulse leaves the transmitter, the transmitter is turned off, and the transducer receiver
is turned on.
The sound energy echoes off the bottom and returns to the transducer. The echo is converted to digital
signals for the microcomputer which computes the depth based on the time it takes to receive a return echo.
The longer it takes for the energy to reach the bottom and return to the transducer, the deeper the water.
The microcomputer sends the computed depth to the instrument display.
8.2 Troubleshooting
1 No display:
• Check DC power connections and DC polarity with voltmeter. Voltage must be between 10.7 and 16.6
volts.
2 No depth reading “--” at all depths:
a Check the transducer for growth or multiple coats of paint.
b Check the transducer cable for cuts and sharp bends.
c Substitute the transducer with a known good Standard Horizon transducer, hold it over the side of the
boat into the water to see if the instrument functions. This isolates cause of problem (transducer or
instrument).
3 Erratic readings while moored
• Check the transducer for growth or multiple coats of paint.
4 Erratic readings while underway
• Cavitation (air) under the face of the transducer. Review installation and reinstall if necessary.
5 When power is applied, display right-hand digit counts up or down
• See section 5.3 Simulation
6 Erratic readings only when engine is running
a Reroute DC and transducer cables away from engine, ignition wires and battery cables.
b Add feed-thru filter capacitor on the positive terminal of the ignition coil.
c Add alternator whine filter to alternator.
d Replace spark plug wire with resistive type.
