Our Doppler log is faulty, shows incorrect readings? How to check it and identify the faulty part of the system?
18 Aug '19, 07:52
The most often cause of Doppler log failure is a transducer. To check it, identify the Signal Processor unit. The Transducer is connected to the Signal processor. You need to measure resistance between core and shields of 2 wires which come from the Transducer, see a drawing.
Resistance should be as below.
(fore beam)between 1 & 2 = 0 to 3 ohm
(Aft beam) between 5 & 6 = 0 to 3 ohm (thermistor)between 3 & 4 = 2.5 kohm at 25 deg C
Additionally, check the insulation resistance, between shield of each 3 wires and the hull. It should be above the 1 MOhm. Any deviations from above ranges will confirm the fault transducer. Get a new one and replace.
18 Aug '19, 07:57