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Old 08-11-2017, 02:18 PM
leok leok is offline
Join Date: Apr 2013
Location: Clarkston, MI
Posts: 435
Default Electrical System Design and Build continued

Power Point is my program of choice. The instructor recommended PowerPoint in the G3X install course I took. It offers many benefits, not the least of which I am familiar and comfortable with it and have it on my computer. Others have recommended Viseo. I don’t have it, and am not familiar with it, so have no recommendation. AutoCad or other CAD software can be used if you are proficient.
As far as Power Point, almost any shape can be created out of the building blocks provided. Multiple shapes can be grouped together to move, copy and paste. Blocks can be built up to cover power, ground, RS232 connections etc. Blocks can be moved and rotated to any position on the page(s).
This is a typical pin out drawing for my PFD;

Start by drawing representations on the left side of the page for each avionics box with each connector included. I started with one page for each box, then added or combined as needed. You can see that power feed from the VPX is included in each device diagram. Refer to the sample interconnect drawings in the G3X manual for examples. Use the Garmin G3X manual interconnect drawings towards the end of the manual for examples when available for connecting specific boxes.

Wire Numbering; some conventions

When doing drawings each wire needs to be labeled. Any reasonable method is acceptable, so long as each wire can be identified. I chose to number my wires by labeled shrink tube. I purchased my shrink tube labeler for $100 on eBay. The shrink tube is needed anyway to close out the shield termination. I identify the wire by origin/end, wire number between the two devices, and segment number … This is how that looks:
GTN/PFD 1a … this equals … 1st wire from the GTN650 to the GDU470 PFD , segment #a
If it goes through a connector it would have a second segment and be GTN/PDF 1b
And if a second wire ran from the GTN to PDF it would be GTN/PDF 2a etc..
For multi conductor wires, they get one number and are connected as follows;
• A single wire is white
• 2 conductor wires are, white, white/blue
• 3 conductor wires are, white, white/blue, white/orange
• 4 conductor wires are, white, white/blue, white/orange, white/green
Wire connections always follow that order from top to bottom in multi-conductor connections so each individual conductor does not need to be called out. i.e. the first pin identified in the drawing connects to white. Second pin identified connects to white/blue, etc..
This convention as well as all symbols are identified in a definitions sheet at the beginning of the wiring diagrams.

Shield terminations are detailed extensively in the installation manuals and follow the general rules
• Signal connections terminate the shield at both ends
• Audio connections terminate the shield at only one end

Pin Out Drawings

Make a diagram for each piece of avionics. This would include each device with each(all) connector(s) for that device shown on the left side of the page. Each connection is shown as lines (one line per conductor) drawn to the right side of the page with the pins, connector number and devices identified. Each wire/multi-conductor is identified by a unique ‘number’ as described above. Like double entry accounting, the page for the connected device then gets an entry with the information reversed (left/right) and the same wire number.

To confirm each device has the correct and needed connections, confirm all communication connections in the ‘communication diagram’ have been made. Then walk through the pin out diagrams in the manuals checking each pin function and number. I walked through the pin out of each device several times to make sure that each pin is connected as needed and confirming proper pin numbering before I stopped finding mistakes. I typed questions on each page, and called Garmin G3X customer support for answers. It took several times through the steps to get everything connected and cross checked.
Building started Oct 5th 2014, Flying since 1/16/2020
RV Hotel, come by and visit if you're in town
Dues paid 2020

Last edited by leok : 06-25-2018 at 03:35 PM. Reason: correct left/right, go figure
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