Instruments

[kalanka]

I have an old Garmin GPS 128 which still works well. However the relay screen in the cockpit has ceased to work. On investigation I find that there are only three input wires to that screen - blue, red, black. Red and black are positive and negative power connections. Can anyone tell me what is the blue? And should it not have a second wire to form a pair? Thanks

 

[kalanka]

I should have said the relay screen is NASA. I also have a Nasa wind setup which is not feeding the cockpit display. Can I check the output from the mast head anemometer with a multimeter to confirm where the problem lies?

 

[bedouin]

Is there an ID on the NASA unit? I guess the blue wire will be the signal in - and that the signal -ve is shared with the power -ve. However hard to know what protocol it is expecting without knowing what the unit is. Has it previously worked with the Garmin? If so then it is probably a NMEA 0183 repeated.

In theory you can probe the connections to the mast head unit with a multimeter - you should be able to find the specific details for the NASA unit on line somewhere by googling

 

[andsarkit]

Connections seem correct with just a blue wire for data.

Have you accidentally changed the output settings on the GPS128? See page 44 of the handbook for details on setting up the NMEA output. The baud rates must the the same on both transmit and receive ends.