John and Larry, thank you for your input. I totally appreciate it, which is
why I reach out to the group...First things first... I will explain what I know
from my observations as a layman.
Here is the trial-and-error method that I used to find the fault... 1. I
removed all devices connected to the Avionics switch (lit with an LED
indicator) which is the culprit.2. I disconnected the wire supplying power to
that switch (the switch status is off) from the power buss. 3. Then turned the
switch on 4. I touched the wire from the switch to the buss bar5. I observed an
arc, and the wire became hot (as in heat).6. No breakers tripped though it was
connected to a 5A breaker7. When I removed the wire from the buss, again a
small arc followed. 8. While the switch was on, I observed the battery drain
from a normal 12+ Volts to as low as 10.5V9. I removed the switch and replaced
with a common toggle switch (rated at 10A)10. I reconnected the circuit to the
buss, and I did not observe arching nor did the wires get hot.11. I kept
feeling the wire for heat for a few minutes before reconnecting devices one at
a time12. After I reconnected all devices, I turned them on one at a time to
see if I still had a problem.13. All devices came back online without any
problems14. The voltage as recorded by the EMS indicated a stable 12.5VDC with
no deterioration.
Today, I went out to the airport and ran the engine, turned on all of the
instruments and between the battery and the alternator, I was able to sustain a
steady 12.5VDC. I ran it for about 5 minutes and shut it down. I reached under
the panel and all wires felt normal (no heated wires).
I hope that helps some.
Luis
On Friday, August 30, 2024 at 10:00:47 AM CDT, Larry Flesner via KRnet
<krnet@list.krnet.org> wrote:
On 8/30/2024 9:34 AM, John Gotschall via KRnet wrote:
Hi all,
I read something about an avionics power connection arcing upon contact
during
troubleshooting.+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Something to support your observations, I learned early on in my electronics
education, working on crypto equipment in the USAF, and 33 years working on
office equipment for Xerox, that if you don't know what normal operation is
you're not really troubleshooting, you're no different than a pig rooting for
an acorn. They often find the acorn but they also spend a lot of time rooting
and find nothing. 🙂
Larry Flesner
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