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Noise & Data Problem

S

SPB W10

Active Member
We have electric whine in the Garmin 530 & 430com headsets and cabin speaker. We have a Chrysler alternator with a noise filter attached to the case and a #6-gauge wire from the alternator ground to the starter mount bolt. The starter has an 0 gauge ground wire routed to cockpit structure.
The JPI EDM 700 downloaded data is unusable. Cylinders #1, #3 & #5 EGT and CHT have ?noise? near the harness we have been told by SAVVY Analysis.
The magneto harness has been checked for shorting to shield and separated from the EGT CHT harness and there was no change.
The alternator field and output wiring are routed under the cylinders which gives plenty of distance from the data harnesses.
Could the alternator noise and the data harness problem be related somehow?
 
SPB W10 said:
We have electric whine in the Garmin 530 & 430com headsets and cabin speaker. We have a Chrysler alternator with a noise filter attached to the case and a #6-gauge wire from the alternator ground to the starter mount bolt. The starter has an 0 gauge ground wire routed to cockpit structure.
The JPI EDM 700 downloaded data is unusable. Cylinders #1, #3 & #5 EGT and CHT have “noise” near the harness we have been told by SAVVY Analysis.
The magneto harness has been checked for shorting to shield and separated from the EGT CHT harness and there was no change.
The alternator field and output wiring are routed under the cylinders which gives plenty of distance from the data harnesses.
Could the alternator noise and the data harness problem be related somehow?
Click to expand...

This sounds more like a ground issue somewhere. Would probably start by verifying engine to airframe ground conductivity. Also be sure the alternator case to crankcase shows 0 ohms.

Larry
 
Here is an update to our audio noise.
While "reracking" the center stack radios, checking for pin condition and treating with corrosion protection, the back rectangular connector assembly of the Garmin GMA 340 audio panel tray was found (visually) with all screws loose. This is where shields and grounds are terminated and this seems to have been the problem for a long time. The speaker and headphones do not have the alternator whine any more. We won't list all of the other components replaced, tested and grounds cleaned, phone jack and aux audio input jack insulators checked etc.
Whewww!
 
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