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From: Dale Rogers <dale.r@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: EC2 problems (was: More MAP measurement questions)
Date: Fri, 20 May 2005 23:00:17 -0400
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John,

   I do electronic troubleshooting for a living. Usually, 
when I have repeated failures of a single module it's 
because something else to which it is connected is "eating" 
it. A likely candidate is a sensor that has too low 
impedence/resistence and therefore is passing too much 
current. Less common in recent years is voltage on the 
return line.  It's amazing how dead a component will get 
with as little as -1.5V on a line that's supposed to be 
zero.

You also might consider getting a voltage regulator 
for the B+ going into the EC2.  I don't have ready access 
to specifics right now, but regulats\or ASICs are a fairly 
standard item.  It might be worth putting a scope on 
your charging circuit to see what kind of spikes the 
alternator regulator is actually allowing out on the 
+12V line.  The RMS voltage (okay, I know that DC isn't 
actually measured in RMS) could be 14.2V but the regulator 
could still be allowing mSec length 20V spikes to pass 
through.  ['course you have to get it *running* again to 
check for that  :)  ]  A separate regulator for the EC2 
might buy you the time you need to find a B+ problem.

   I'd come out and help you look for it, but it's a 2000 
mile flight, and I still have to work next week.

Regards,
Dale R.


> From: "John Slade" <sladerj@bellsouth.net>
> Date: 2005/05/20 Fri PM 08:51:53 EDT
> ...
> The test went well. We plugged my EC2 into Buly's harness and immediately
> got the NOP message on his EM2. We didn't check the spark, but the engine
> would not fire at all. We then reinstalled his EC2. The NOP message went
> away, and the engine fired up immediately on cranking. There we have it. My
> EC2 is dead. Next question - why is it dead, and did I fry it when I
> connected it to the old wiring? Have I corrected the problem by rewiring
> everything? Of course, we could have tested my wiring by installing Buly's
> EC2 in my plane. He didn't offer, and I didn't ask :)
> ...