New NMEA Junction Box: suggestions

[nigelmercier]

I've finally got round to replacing the rats nest of wires connecting my various bits of NMEA kit. This is the box that will now live in the chart table:

It has dedicated terminals for: CP180, a 3-way switch to the CP180 input port, HP-33A AIS, ST60 Graphics, GX2100E VHF, and six USB ports (housed in the box on the right, along with a USB hub).

I've started wiring the interconnections, but it's going to be tedious to keep the wiring neat. I wonder if it would actually be better to have loose wires, so the connections can be followed. Opinions?

Also, any thoughts on how best to create a NMEA GND bus?

 

[mlines]

No thoughts on the GND but thats a great idea compared to the rats nest. I might pinch the idea. I guess that you could have left room at the bottom of the box so that the interconnect wires drop neatly down to the bottom of the box and then across and back up to where the connection needs to go.

 

[salar]

That all looks very neat, but you are doubling the number of connections needed and each one is a point of failure, and using crimp connectors on tiny data wires. I would have ( and did) use soldered connections and shrink tube over. It didn't look as neat but it never failed.

 

[Tintin]

Looks lovely. I did similar, then needed to move a wire from one end of one of the conn blocks to the other. I now have them fanning out and with enough slack to reach both ends, with the slack taken up by small cable ties. Good job though.

 

[yoda]

very neat. Surely the common ground is just a matter of joining the relevant terminals in a daisy chain. My serial data always seems to need a serial to USB converter, how do you achieve this or am i missing something? For the interconnections I would use groups of wire and run them through the small bits of spiral cable tidy as you have done at the top. A label on each set of interconnections telling you what it outputs or inputs will help tracing in the future.

Yoda

 

[nigelmercier]

very neat. Surely the common ground is just a matter of joining the relevant terminals in a daisy chain...

Yes, I thought of that at 2am today

Thanks for the kind comments on neatness. Apart from cutting the cores to the correct length, the secret was to bind the wires with a thin bit of copper wire, then apply dabs of clear water-based acrylic lacquer to the bundle, allow to set, then remove the wires and fill in the gaps. They can still be pulled apart if necessary, but are held firmly enough.

Lacquer here:http://amzn.to/1zYvEkR handy stuff.

 

[Upnorth]

I use these http://www.winford.com/products/tta35.php for data wires. You can create a 'commoning block' by soldering links into the holes between the connector blocks.
http://www.winford.com/products/pic/tta3510-ft_large.jpg

 

[Saguday]

Not a bad idea to have lots of grounds brought to a common sturdy point, chaining them serially could cause lots of issues if one failed or became dodgy and risk creating ground loops inadvertently too.

For identification why not just attach wire tags to each wire and label them - or at least colour code or number them - and keep a cheat sheet somewhere to remind you what they are?

Our IP is wired completely like this with everything labelled, deep joy...

 

[Billjratt]

I used the neutral bus bar out of an old domestic consumer unit to common up all the power and signal "blackwires" and fed it directly from the central NEG.
I left a sort of organised birdsnest of the rest, as it allows me to move them around easily.

 

[nigelmercier]

[UPDATE]

All done, except for NMEA ground (currently bundled together, soldered and heat-shrink).

This is it in-situ inside the chart table, just behind the computer:

And this is my new, uncluttered, chart table:

 

[Birdseye]

I've finally got round to replacing the rats nest of wires connecting my various bits of NMEA kit. This is the box that will now live in the chart table:

It has dedicated terminals for: CP180, a 3-way switch to the CP180 input port, HP-33A AIS, ST60 Graphics, GX2100E VHF, and six USB ports (housed in the box on the right, along with a USB hub).

I've started wiring the interconnections, but it's going to be tedious to keep the wiring neat. I wonder if it would actually be better to have loose wires, so the connections can be followed. Opinions?

Also, any thoughts on how best to create a NMEA GND bus?

Maybe its me but I really like the neat appearance your work already has. Fancy doing a second?

 

[yoda]

Yes, I thought of that at 2am today

Thanks for the kind comments on neatness. Apart from cutting the cores to the correct length, the secret was to bind the wires with a thin bit of copper wire, then apply dabs of clear water-based acrylic lacquer to the bundle, allow to set, then remove the wires and fill in the gaps. They can still be pulled apart if necessary, but are held firmly enough.

Lacquer here:http://amzn.to/1zYvEkR handy stuff.

Nigel

Can you expand on how you achieved the USB outputs without using a serial to USB converter or is it all in the box?

Yoda

 

[nigelmercier]

Can you expand on how you achieved the USB outputs without using a serial to USB converter or is it all in the box?

Inside the black box with the green LEDs are the printed circuit boards from 3 StarTech USB to serial converters and a generic USB hub.

The StarTech 2-port USB to serial converters http://amzn.to/1ccP1fG have all the working parts in the module in the cable, so it was relatively simple to bring out the wires that I needed, although a bit fiddly with 1mm pitch connectors.

Maybe its me but I really like the neat appearance your work already has. Fancy doing a second?

Thank you, but it took a long time. If I was to do it again, I would do as I did with the second row of terminals: remove the red insulators and use a "bum crimper". This allows two terminals to stack better back-to-back. Interestingly I did a test pitting a standard red crimp against a modified crimp as above, the modified crimp was stronger (as expected) but not by much. This makes me a bit happier about using insulated crimps in future.

"Bum crimp" picture below. If this was in the open I would use some heat-shrink to support the cable.

 

[nigelmercier]

And today I did my first bit of fault finding: the NMEA repeater in the cockpit was saying No Data. It took seconds with an oscilloscope to locate the feed to the unit and discover it was set to the wrong Baud rate. In my old system, this would have taken ages.