REFLECTOR: Intercom Noise

[Brian Michalk]

I don't understand the purpose of the barrier strip.

It appears that most of the bottom studs only have one wire attached.  I 
don't see how these are grounded.  Does this barrier strip actually have 
an internal bus that connects all of the studs?

On 03/08/2011 11:55 AM, aminetech at bluefrog.com wrote:
> A while back I reported that I found a bad ground and eliminated the intercom noise. After 20 hours of quiet operation, the noise is starting to return. It's infrequent and not to annoying, but I don't want it to get worse. I've attahced a pic of the barrier strip where I found the bad ground. (I'm sending the pic of the left side separately). My plane was built with a second battery and I believe this barrier strip was part of the backup system. The backup battery and alternator were removed before I bought the plane, so I'm not sure.  Here is what I know.
>
> Terminal B is the EI mag wire.  It goes to the mag switch and the circuit returns through the shield and terminates at terminal C which appears to be grounded to the firewall.
>
> Terminal 1 is the power wire going to the EI.  With the EI mag switch up, B is grounded and 1 has 11.8 v.  With the mag switch down, B is not grounded and 1 has no voltage.  Is this how EI s are normally wired?  I figured the mag switch would simply cut off the power.
>
> Terminal 8 has 2 wires.  One is power from the master.  I don’t know where the other wire goes.  It reads 12.4 v with the master on.
>
> The terminal 2 wire goes to the EI ground.  I need to check where it is grounded to.
>
> Terminals 8 and 9 are connected and read 11.8 v when the EI mag is on and the voltage goes up to 12.4 v with the EI mag off.
>
>
>
> Terminal 3 is the bad ground, and 4 is a mounting screw that is also grounded to the #3 wire. I didn't replace anything, just removed #3 and 4 and put back on. Before I removed them, the #3 screw was reading 5-900 ohms, now it is 0. With both 3 and 4 removed, the EI did not operate. With 4 connected the EI ran, but rough at low rpm. With 3 also connected it ran fine.
>
> I would appreciate anything anyone can tell me about all this.  If there is something that I can remove, I would like to do so.
>
> John
>
>
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