Mailing List flyrotary@lancaironline.net Message #67996
From: Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EC2 Trouble shooting (cont.)
Date: Tue, 13 Jan 2026 19:19:27 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
I assume EC2 and EC3 are similar in this respect.
Each controller has its own 5V regulator.

It's true that the outputs are switched (separated) with A/B relays. However, several CPU inputs (mode selection, mixture voltage, program voltage, cold start ...) are shared and CPU inputs have diodes to +5V and to ground to protect them. That means that if you cut the 12V power to one controller all these inputs will be pulled to zero on the other controller.

So not really fully redundant.

I didn't realize that when I installed the EC3 in my RV-4. I have separate power switches and fuses to A and B controller.

Finn

On 1/13/2026 2:12 PM, Doug Lomheim rv9flyer13b@gmail.com wrote:
David:  I always wondered that myself, since my EC2 instructions didn’t specify what Pins 33 and 34 did, once inside the EC2.  

My manual only said they were 12V, and go to the “Controller Power Switch”.

Doug     








From: David COOK hoursaway1@comcast.net <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EC2 Trouble shooting (cont.)
Date: Mon, 12 Jan 2026 20:19:00 -0500 (EST)
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Isn't there a separate power input for A & B, and also a separate ground for A & B  ????


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