To test the masthead unit, you'll either need someone at the masthead or bring the unit down and use a test cable to connect it to the Hornet 4. With an analog voltmeter, place the negative lead on the black wire of the mast
cable, and the positive lead on the red wire. Have someone slowly rotate the direction vane thru 360 degrees of rotation. The voltage should vary smoothly from approx. .3v to approx. 6.1v Do the same with the blue wire and the green wire. These are the phase outputs that determine the angle. With the vane at exactly 90 degrees, the voltages should be: Red 3.25v, Green 0.47v and Blue 5.93v and at 270 degrees: Red 3.25v, Green 5.93v and Blue 0.47v. Any problem with these measurements indicate a problem with the circuit board in the masthead unit. If they are ok, you can measure the Hornet 4 output at the meter. Black meter lead on common, red on Sin, voltage will vary from +2.5v to -2.5v Same on Cos. With vane at 90 degrees, you should have +2.3v on Sin and -2.3 on Cos and at 270 degrees, -2.3v on Sin and +2.3v on Cos.
As for the remote
depth indicator. Check the area where the jacket of the cable from the Hornet 4 to the meter was cut and stripped. Iv'e seen many times where the individual wires themselves were slightly cut into when the cable jacket was removed. This does not present a problem at first but eventually corrosion
takes over and creates an intermittent connection before finally breaking into. If this is ok and the other connections are ok, then you need to open the meter up. First remove the Dessicator plug
from the back and then loosen the many screws from the rear. A battery
screwdriver will come in handy here, these are long fine thread screws. Seperate the two halves of the meter and inspect the the LCD connections. This is another area of frequent problems once any moisture has gotten into the meter. You can pull the LCD and lightly clean the long leads with very fine sandpaper. Do not pry up on the LCD itself as it is easily broken. Instead, pry up on the diffuser under the LCD which will then push up on the LCD. The diffuser is probably stuck to the microprocessor underneath with doublesided tape but should come loose easily. Pop the dessicator into the oven
at 250 degrees for a couple hours or so to dry it out before replacing it. If this does not fix the problem, if you have another digital meter in the system such as boat speed or wind speed, you can swap them to determine if the problem is in the meter or in the Hornet 4. You'll find a 4 position DIP switch on the circuit board in the meter. The depth meter has positions 1,2, and 3 turned on. Boat speed has position 2 on and wind speed has position 1 on. Simply change them as needed and swap them out.