RDP 139 Loses GPS and no Nmea output



My RDP 139 is coupled to GPS, radar and sounder.
It all works fairly well but I have two problems.

1. GPS Loss of position
Most times I use the system, at no particular time, It loses the GPS position.
Position does not come back until I restart the unit.
In a 6 hour day fishing I may have to restart it 2 or 3 times.

2. No Nmea signal output on Data Port 2
The RDO 139 is coupled to a Simrad AP11 Autopiloit via Data Port 2.
I have set up the port and switched on the various Nmea sentences needed.
There was a Blue cable on that port and I omned it out and found the + & - connections on Pin 1 and Pin 2. No data received by the Autopilot.
I eliminated problems with the Autopilot by connecting a Garmin GPS to it and all works correctly.
I also bought a new Black data cable and so eliminated a cable problem
So the problem is definitely in the RDP 139 [or my settings]

Maybe the unit is just tired and old [like me].
What is my best course of action to get it working correctly ?


Roy Page

Johnny Electron

Staff member
If you have sentences turned on from the RDP139 data port two; you should have about 2.5 to 3.5vdc jumping around if you us a DC meter on the output wires. If you don’t, then it sounds like it has a burned out NMEA output. The GPS issue could be related to your port problem in the manner that maybe the unit has internal corrosion and the data port 1 is not working well. It could be that the GPS antenna itself is having problems. I would start by having a dealer or our service center evaluate the RDP139.


I did check the output on pin 1 and Pin 2no sign of any voltage at all.
Can't find a local dealer who is interested in looking at the unit.
So do have to send it to the WA service center ? Or buy another display unit.

The unit had a lot of "no use" sitting in the sun in Florida so I suspect that corrosion is the problem and the Mnea unit bunt out.

What other display is compatible with the 6 pin plugs ? RDP 149 maybe ?
Would love to keep the Radar, Fishfinder and GPS unit and plug them all into a later model.
Guide me please.




The RDP149 will use all the same accessories as the RDP139.