GEM 1200 Problem

Kyler Laird wrote:

Jim Kaufeld writes:

Anyway, the GEM has an intermittently flaky display. Sometimes it goes crazy
and the bar graphs and digital temp readouts start fluctuating wildly. It
isn't just one engine and it isn't just one cylinder. Its all of them.

Does this look familiar?
http://lairds.org/Kyler/photos/disk0024/mvi_1757.avi
(It got much worse than that.)

Yes ... that looks familiar!

First verify that your engines are sufficiently grounded. Then
verify it again. Check your alternators while you're there.

What, exactly, should I check? I would have assumed that since the starters
work on both sides, the engines are sufficiently grounded. Is there typically
a separate ground that goes to the engine? Should I add one?

Next see if you can isolate a bad probe (or probes) by flying with
some disconnected.

One thing I've noticed is that when the GEM is working the CHT on the RE, #2
varies. I figure that either something is wrong with that probe or the
connections to the probe. Can just one badly connected probe -- or maybe a bad
probe -- make the whole instrument dance?


Thanks for the help.

Good luck.

--kyler

Jim Kaufeld