37-pin Split Cable

[jspar]

Hello,

Long time fan, first time poster. I bought a plane with Skyview and I am considering adding a second display for redundancy, copilot, etc. Would it be possible for me to take the current 37 pin into the back of my skyview, plug it into this:

DB37F RS-449 "Y" Cable - Stonewall Cable

The length of this RS-449 straight-thru

www.stonewallcable.com

Then just plug each new 37 pin into each dynon? this seems tons easier than splicing (and potentially safer with fewer connections exposed, etc.) I would also consider each skyview on it's own breaker, but this seems so easy.

Apologies if this has already been explored, I'm just searching for the most pain free way to connect these!

 

[Raymo]

For most things, it would likely work. Where I see an issue is with the power to each screen, which should be on independent breakers/fuses. Each screen requires two pins to be powered (not for redundancy). I recall spending days soldering wires to join the two screens so it would be great to use something like this. You could, however, use that product but break out the power wires to their power sources. The other down-side is that you'll lose all the color coding that jives with the install manual but that problem can also be solved with labels.

 

[jspar]

Yeah I agree. Would definitely have to cut into the wires and break out pins 1, 20, 21, and 22 for each. If I can find those, would likely be very easy after that!

Probably lose some redundancy but gain some simplicity and reduce points of error.

I also thought about having a custom printed circuit board with 37 pins just hooked into each other. Very similar to the Dynon network hub, just 37 pins. That would also make it easy to split them out.

With regard to the color coding, it would still be color coded to the terminal with Dynon’s original cable, and after that the only things that wouldn’t be color coded would be the split out power wires. Seems like a $190 time saver that would only require me to split out 4 wires and hook up a breaker.

 

[RaymondJ]

I've dealt with these types of cables before (having had to cut one open and do a field modification! non-aviation, though) -- and I think cutting the cable open to find the wires will pose more problems than it solves!

• The interior wire markings aren't guaranteed to be per any standard (and heck, some times I've just found a bundle of totally white wires). In my case, I had to use a tone-finder to trace circuits since the interior pairs weren't labelled.
• Cutting the outer plastic jacket drastically decreases the cable's ruggedness, since the interior conductors are fairly thin (probably 28-30awg).
• Once you've identified the right wires, then you have to figure out how to make a rugged splice to a much larger conductor...

If you have the capability, a breakout / hub PCB sounds like the best path forward!

Signal-wise, there are also several pins that can't be cross-connected, or you will be met with electrical gremlins:

• Connecting the USB signals (particularly the +5V power) to each other may cause havoc. The +5V signals may try to fight each other and cause burnout / unexpected results. USB data lines tied together is the equivalent of a USB A to A cable, which isn't allowed per the USB spec, and the behavior here could get quite gnarly.
• Several pins (32-37) are clearly marked as do not connect. All bets are off if you tie these together; if these are electrical outputs which aren't cross-strap friendly (similar to USB +5V power), you will get gremlins. We don't know for sure, so I'd follow the manual here.
• Dimming output (pin 26) is specifically called out as do not parallel / hook together.
• Backup battery power is specifically called out as do not hook together.

 

[jakej]

I've been using the 5 x 25way 'Hubs' that were available from Maker Plane - except for pwr/gnd & USB cable each screen connects to the hub separately with other inputs/outputs going to various devices. I find this is much simpler & easier for troubleshooting with a multimeter.