I've got a Nexus system on my boat which appears to be from the late 1990's (I just got the boat last year). It has a Nexus server, log, depth and wind gauges, a Multi Control, a Multi XL display and a remote control.
Recently the speed display has been reading 0.00 sporadically and today it didn't work at all, all day :-(
I checked the voltage across yellow and screen (pins 2 and 4) and it read about 0.02 volts at the dock (I was unable to check while the boat was in motion). I am assuming this value is normal based on the manual stating: "When not rotating, the value should be fixed at either about 0V or 5V DC".
I'm thinking the likelihood of a mechanical block of the wheel under the hull is unlikely. I sail on freshwater and the boat has only been in the water for 6 weeks so far this year. According to the manual, the model ("Art No.) of the log transducer is 20700
Any thoughts as to the best way to troubleshoot this further?