If any of you
guys out there tend toward OCD and are currently wiring your
plane, here's a heads-up.
I probably
know too much (or maybe not enough) for my own good about
electrical stuff, including issues like electrical noise &
ground loops. So when I created the wiring harnesses for my
RV-7 a couple of years ago, I tried to make sure I avoided
ground-related issues by carefully routing grounds *exactly*
where they should be according to the avionics documentation,
and making my best educated guess when I couldn't find any
good documentation.
Well, I laid
a couple of mines, & didn't step on them until I installed
the instruments to do a test powerup, prior to closing out the
fuselage. The intercom wouldn't power up, and neither would my
Anderson engine monitor. After spending a couple of days
digging through my extensive (but not very well done) notes, I
found the sources of my problems.
The intercom
has a 'floating' chassis, and you're directed to run the
ground wire to the radio. I did this; running the ground to
the power ground in the GNS430's tray. I also thought it would
be smart to ground the Anderson monitor to the main ground
point in the EC-2, so I tied it to pins 19 & 37, which are
then grounded to the engine block. (I documented the power
connections well, but the ground side...not so much.)
So on my 1st
real power-up test of the system, not wanting to put multiple
high dollar instruments at risk, I only powered or installed a
single instrument at a time. Anyone see the mines yet?
Charlie