Tapping into Raymarine Power Cable

[nelson.peter]

My Raymarine chartplotter is 8 years old and no longer supported by Raymarine. So I have chosen to opt out and go with PC-based navigation. But we want to get the data out of the chartplotter (via NMEA) and into our PC. I have communicated with Raymarine and they have given me the necessary wiring diagrams and schematics to go into a serial port on our computer.

Now I need to figure a way to tap into the power cable running to my chartplotter. It has a vinyl jacket carrying a bunch of instrument wires. We need to tap into a couple of the wires and solder them to the wires in a serial cable.

I am thinking of splitting the jacket somewhere behind the nav panel (where it is dry) and then somehow splicing into the 2 wires that I need. I am pretty sure I can figure out using a standard volt-ohm meter how to figure out which wires to tap into.

But how do I do the splices? Do they make butt splices for instrument wire? If I solder a couple of these instrument wires together, then how do I finish them off to give the splice the needed support? Heat shrink? I don't have much experience with this small of wire. Any other suggestions on the installation would be appreciated.

[s/v Thea]

I would cut cable, add ring terminals and re-connect using a terminal strip, you can then connect your other wires to correct terminals on the strip.

Doug

[nelson.peter]

Doug (or anyone else) --

I'd be afraid that all those connections through the terminal strip might develop voltage loss which might affect the integrity of the data being transmitted.

[nelson.peter]

So today I spliced into the Power/Data cable to my chartplotter and lost Seatalk!! Per the attached schematic, I cut the orange and yellow wires in the cable and butt-spliced them. On one side of each butt splice I added a pigtail that ran to the serial cable going to my PC, again per the attached schematic that Raymarine provided me. I figured one butt splice per wire would provide a better signal than a couple of ring connectors and a bus bar, so I went that route.

Now I have lost Seatalk between the radar and chartplotter! Both (still) work independently, but don't talk to each other. And to make matters worse, I'm not able to get any data to my PC.

We measure a -.17V out of the NMEA OUT cable. This has me thinking things are hooked up backwards. One is blue with white specks, which I took to be 'blue' and the other is white with blue specks, which I took to be 'white'. So maybe I need to reverse these wires, yes?

But the bigger problem may be with the NMEA IN coming from the Power/Data cable. I fear that because I broke into the cable, peeled back the thick, wire mesh RF shielding, and made some good butt splices on the yellow and orange wires that this has caused me to lose Seatalk. Can you confirm that or not?

I was thinking of wrapping the splices with tin foil before taping them up. But I would like to know they are working properly first. Any ideas on how to confirm that would also be helpful.

I'll stop here and answer any troubleshooting questions you may have. Thanks a lot for your help.

[noelex 77]

Dear Peter
I think the first step is to try and determine why you have lost "Seatalk" between the radar and chartplotter. Can you specify what functions you have lost?
The wire you have cut is not part of the seatalk bus. Is it possible you have cut into a Raymarine HSB cable instead of the power/ data cable?

[nelson.peter]

Thanks. We looked behind the chartplotter and found the Seatalk plug was loose! So that really helped.

Now we are trying to resolve a new problem -- the PC won't launch! But that is separate an unrelated. Not sure what that is all about, and after we get that resolved we can find out if we have NMEA going into the PC -- which I don't think will happen, but we gotta check. Back in a bit.

[nelson.peter]

OK, computer is up and running, but as expected, no NMEA data to the PC.

[Beausoleil]

Peter,

According to the diagram, the NMEA Out cable should have only two wires and a shield - blue for NMEA OUT +, white for NMEA OUT -, and a gray shield wire. You wrote that "We measure a -.17V out of the NMEA OUT cable. This has me thinking things are hooked up backwards. One is blue with white specks, which I took to be 'blue' and the other is white with blue specks, which I took to be 'white'. So maybe I need to reverse these wires, yes?"

Negative in this case means signal ground, not necessarily a negative voltage. The electrical spec for NMEA 0183, RS-422, uses +5V for a binary one, and 0V for binary zero. -0.17V would be interpreted as a 0. Some electrical specs use +15V for zero, and -15V for one, for example.

I think noelex_77 is on the right track. Blue/white specks and White/blue specks sounds suspiciously like one of the pairs from an ethernet 4-pair cable - the other pairs being green, orange, and brown with specks. Raymarine's HSB2 is Ethernet. Does the old Pathfinder have an HSB2 input? I thought it didn't - but HSB could use a paired cable similar to ethernet 4-pair (too lazy to look it up at the moment).

Since there's no constant voltage output from the cable, your meter will read erroneously. It's not DC, nor is it 60Hz AC.

Are you positive (pun intended!) that you tapped into the right cable? I don't see anything about SeaTalk on either the NMEA out cable, or the power cable (only NMEA in)