X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ug-out-1314.google.com ([66.249.92.172] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2605741 for flyrotary@lancaironline.net; Wed, 19 Dec 2007 15:47:44 -0500 Received-SPF: pass receiver=logan.com; client-ip=66.249.92.172; envelope-from=msteitle@gmail.com Received: by ug-out-1314.google.com with SMTP id o4so447334uge.7 for ; Wed, 19 Dec 2007 12:47:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=rW0RFoRWJlMaiwpU22+g2qChNlwyC0TBQiz7dgs+mZk=; b=NjfuOINbxauYMoqbIGRIMeqp0O8AlzSuwmvGlVahiKquL8kFBdwIflcvbvq9NmbR8j5/rICVG62JQmBRwKkSI6vDRxwF+hYv6ynjFL8B316mZZ5XoV5P7bczVXpOgyhPLRo8VvMbzy4/cDQ9aFAtwviK9yyiLOMUies8Dh4G8Bg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=XR1bjqM01vXxHQgFAOpB8zFGohMhkYajmAH0iW/9pzMaotBezttcNzM7z0ly97tO/IKKdzRpcVoBpAJKeJIJZB9LeWe7PvyiO0epLEVRpTu7ICUeMu6yg5fvJb++hp246XzTI/pqcKogg0y5Rn3yjLyfCRPv/DF+426/Fm4nl/8= Received: by 10.150.218.10 with SMTP id q10mr3796586ybg.50.1198097220879; Wed, 19 Dec 2007 12:47:00 -0800 (PST) Received: by 10.150.146.16 with HTTP; Wed, 19 Dec 2007 12:47:00 -0800 (PST) Message-ID: <5cf132c0712191247l793ea363l17747e4b1ae36ea5@mail.gmail.com> Date: Wed, 19 Dec 2007 14:47:00 -0600 From: "Mark Steitle" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: EC-2 troubles In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_7348_10570429.1198097220870" References: ------=_Part_7348_10570429.1198097220870 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Al, What I don't understand is why am I just now having this problem. I've bee= n flying for 11 hours and this problem just recently surfaced. The only change I remember doing recently was replacing the electro-mechanical injector staging relay with a solid state relay. Tracy has recommended tha= t I add a second diode from the second output terminal of the SSR to ground. I will try that, but I will try to reproduce the failure (on the ground) by triggering the radio, and also turning the transponder from off to standby to on. The transponder is the closest piece of electronic gear to the EC-2. As I understand it, the transponder also puts out much more wattage than the nav/com. One more possibility is that the tach lead coming from the EC-2 is unterminated. I have since learned that it is bad practice to leave wires unterminated. So, I will remedy that this weekend too. Also, I would like to know where the best place would be to connect a scope lead on the EC-2 to look for noise. That seems like the easiest way to track down this problem. I will ask Tracy for suggestions before proceedin= g with the scope. Mark S. On 12/17/07, Al Gietzen wrote: > > I have separated the injector wires and the coil wires from the > rest. There's a ground block located between the two with a connection > through the firewall to another ground block and engine ground. Batterie= s > are in the back though. There's a #2 welding cable going from the ground > block to the battery. It routes down the right side away from all the > smaller wires. > > When you say "smaller wires" do you mean current carrying wires that powe= r > things, and return current from the alternator =96 or just instrumentatio= n > wires? Good practice, especially in a composite plane, is to use twisted > pair (power/grnd) to cancel noise. Having power leads away from the groun= d > return forms a big loop antenna for radiating EMF from wires that carry > noisy current. I suspect that is not much help at this point. > > > > Probably the noisiest wires we have in our planes are the alternator > output and the power for the coils and injectors. > > > > The nav/com is mounted near the EM-2 and could possibly be the culprit, > based on Al's recommendations. The EM-2 display is right above the > nav/com. Maybe I need to move the nav/com to the back of the plane? > > > > The Nav/Com itself should not be an issue, the antenna lead should only > 'leak' low levels of RF unless the impedance match isn't good, or bad > connection to the antenna. Is your EM2 display remote from the Data > Acquisition Module? Those leads, the serial leads between the EM2 and EC= 2, > and the power leads to the EC2 should be kept away from the noisy wires. > > But then, I'm no expert on this stuff. Tracking down electrical noise > takes an expert with an oscilloscope. > > You were on a good track suspecting the solid state relay if the problem > did not occur prior to installing it. You may need to add snubbers there. > Switching relays definitely generates a noise spike. > > Al > > > ------=_Part_7348_10570429.1198097220870 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Al,
 
What I don't understand is why am I just now having this prob= lem.  I've been flying for 11 hours and this problem just recently=  surfaced.  The only change I remember doing recently w= as replacing the electro-mechanical injector staging relay with a solid sta= te relay.  Tracy has recommended that I add a second diode from t= he second output terminal of the SSR to ground. 
 
I will try that, but I will try to reproduce the failure (on= the ground) by triggering the radio, and also turning the transponder from= off to standby to on.  The transponder is the closest piece of e= lectronic gear to the EC-2.  As I understand it, the transpo= nder also puts out much more wattage than the nav/com.  
 
One more possibility is that the tach lead coming from the EC-2 is unt= erminated.  I have since learned that it is bad practic= e to leave wires unterminated.  So, I will remedy that this weekend to= o.   
 
Also, I would like to know where the best place would be to = connect a scope lead on the EC-2 to look for noise.  That seems like t= he easiest way to track down this problem.  I will ask Tracy for = suggestions before proceeding with the scope. =20
 
Mark S.

 
On 12/17/07, Al Gietzen <ALVentures@cox.ne= t> wrote:

<= span style=3D"FONT-SIZE: 12pt">  I have separated the injector wi= res and the coil wires from the rest. There's a ground block locat= ed between the two with a connection through the firewall to another ground= block and engine ground.  Batteries are in the back though.  The= re's a #2 welding cable going from the ground block to the battery.&nbs= p; It routes down the right side away from all the smaller wires. =20

When you say "smaller wires" do= you mean current carrying wires that power things, and return current from= the alternator =96 or just instrumentation wires?  Good practice, esp= ecially in a composite plane, is to use twisted pair (power/grnd) to cancel= noise. Having power leads away from the ground return forms a big loop ant= enna for radiating EMF from wires that carry noisy current. I suspect that = is not much help at this point.

 

Probably the noisiest wires we = have in our planes are the alternator output and the power for the coils an= d injectors.

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">The nav/com is mounted near the EM-2 and cou= ld possibly be the culprit, based on Al's recommendations.  The EM= -2 display is right above the nav/com.  Maybe I need to move the nav/c= om to the back of the plane? =20

 

The = Nav/Com itself should not be an issue, the antenna lead should only 'leak' = low levels of RF unless the impedance match isn't good, or bad connection t= o the antenna.  Is your EM2 display remote from the Data Acquisition M= odule?  Those leads, the serial leads between the EM2 and EC2, and the= power leads to the EC2 should be kept away from the noisy wires.

But then, I'm no expert on this= stuff.  Tracking down electrical noise takes an expert with an oscill= oscope.=20

You were on a good track suspec= ting the solid state relay if the problem did = not occur prior to installing it. You may need to add snubbers there. = Switching relays definitely generates a noise spike.

Al

<= span style=3D"FONT-SIZE: 12pt"> 


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