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Reply-To: "David Carter" <dcarter@datarecall.net>
From: "David Carter" <dcarter@datarecall.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-984987@logan.com>
Subject: Re: [FlyRotary] Re: EC2 problems - solved
Date: Sat, 4 Jun 2005 22:40:30 -0500
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TDRs are pricey and not generally or commonly available.  A cheaper way of
finding the type of "intermittent open" that bit John is to use an "analog"
volt-ohmmeter and use the ohmmeter function to check each wire, pin-to-pin
(one probe held to pin on one end of a particular wire and other probe held
to tip of pin on other end of wire harness.)  Takes time to assure you get
on correct pins to check a particular wire.
    -  While holding probes (or have female or mail pin/jack ends on your
test leads so you can slip the probes onto the pins/into the receptacles),
wiggle the wiring harness while watching the needle of the ohmmeter.  If it
wiggles, you have an intermittent/bad connection, usually at a pin in one
connector or the other.

TDR is really good for LONG wires, for example, from avionics bay in an A-7
(or F-16) back to components in the tail end of the aircraft, going thru
several connectors on the way.  It is really nice to know approximately
where the break is.

David

----- Original Message ----- 
From: "Dale Rogers" <dale.r@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, June 04, 2005 10:21 PM
Subject: [FlyRotary] Re: EC2 problems - solved


> FWIW, if you think you have such a problem, finding someone
> with a Time Domain Reflectometer (TDR) can save a lot of troubleshooting
time.  Check an open-circuit wire from each
> end.  If the reading is different, you have a bad wire.  The
> time signature can even tell you how far down the wire the
> break (or even partial break) is.
>
> Dale R.
>
> > From: Bob White <bob@bob-white.com>
> > Date: 2005/06/04 Sat PM 07:27:31 EDT
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Subject: [FlyRotary] Re: EC2 problems - solved
> >
> > Congratulations John,
> >
> > What a relief it must be to actually have an answer.  A broken wire
> > under the insulation is sometimes one of the hardest problems to find.
> > It could have been worse.  It could have worked till heat or vibration
> > made it quit in flight.
> >
> > Bob W.
> >
> > On Sat, 4 Jun 2005 15:40:43 -0400
> > "John Slade" <sladerj@bellsouth.net> wrote:
> >
> >> Tracy and others.
> >> Following more than 12 months of battling with EC2 issues I'm pretty
sure
> >> it's Eureka day!
> >> After rewiring and testing for almost 4 weeks I plugged the EC2 in last
> >> night, and got exactly the same symptoms as before. NOP flashing
indicating
> >> no communication. I took the EC2 to Buly's plane and tried it in his
> >> installation. Same NOP, so I was thinking I'd fried it again. Before
sending
> >> it back yet again I decided to install it my plane one more time and
see if
> >> there was a spark.
> >>
> >> To my amazement it worked. No NOP, and I could bring up the EC2 data.
The
> >> only thing that changed overnight was that I moved the cable to unplug
it. I
> >> climbed in the back and found that I could make the NOP flash, or stop
> >> flashing, by moving the cable. I haven't taken the connector apart yet,
but
> >> I'm expecting to find a broken wire inside the insulation, probably
near a
> >> solder joint at the pin. Whenever I bent the connector outward for
testing
> >> it made contact. When I bent it back to plug it in, contact was lost.
> >>
> >> Bingo!
> >> John
> >>
> >> Just guessing, but maybe the new EC2 can't communicate with a
pre-autotune
> >> EM2 like Buly's. ???
>
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>
>