Message-ID: <001801c1c135$b357fcc0$0200a8c0@Charlie>
From: "Charles Kohler" <ckohler1@cfl.rr.com>
To: <lancair.list@olsusa.com>
Subject: Connectors--Bad
Date: Fri, 1 Mar 2002 10:28:12 -0500
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Hello Everyone,

For some time now I have been receiving the Lancair List, but this is my
first post to it.  I have found the list to be both educational as well as
comical at times.  Never a dull moment.
I am replying because of Brent's comments and views of soldered wires vs.
crimped wires.  My views are somewhat different based on experience I
have gathered over the past seven years.

To date, I have been involved with approximately 16 Lancair aircraft.  They
range from the 320 to the IV-P.  I have built and installed instrument
panels, installed and trouble shot instrument panels built by others,
rebuilt instrument panels built by others, fabricated complete wire harness
assemblies, installed electronic engine controls on standard aircraft
engines as well as liquid cooled V8 engines, developed power distribution
switching networks for multi bus electrical systems, and performed various
electrical and avionics upgrades to completed aircraft.

Many of the electrical problems or glitches I have encountered have been
directly related to soldered wires, or improperly soldered wires.  Common
places seem to be at small switches and solder-cup connectors.  Small
switches come with elongated holes in their tabs.  The purpose of these
holes is to insert wires prior to soldering so a good contact can be
established between the wire and the switch tab.  What I have found in the
field is that a good portion of switch wiring glitches are caused by wires
that are not inserted in the tab holes, and where minimal solder is used to
attach these wires.  Small, dense solder-cup connectors normally have their
cups very close together.  This makes it difficult to get to each individual
cup in the connector.  What I have found here are solder joints containing
minimal solder thus creating loose wires in the cups.
Another common area I have run into problems is in line wire splices.
Roughly 99% of all glitches I have encountered with in line splices has been
from incorrect splicing of the wire before soldering and incorrect soldering
of the wire itself.  In all these instances the wires were not twisted
before soldering.  What I find disturbing about this is that these problems
were created by individual builders and professional avionics shops.

Soldering is as much an art as it is a science.  Very few individuals can go
out to the local Radio Shack, pick up some soldering gear and start
soldering.  There are numerous items that need to be considered.  What kind
of soldering is to be done?  Do you need to use Rosin Core, Silver, or Acid
Core Solder?  What size soldering gun do you need?  How many Watts?  What
size tip?  What kind of solder removal tools will be required?  What kind of
solder joint cleaner do you need?  Once all this has been determined, now
soldering can begin.  However, before you begin to solder, the wires have to
be properly attached to each other.  The correct amount of solder required
for the splice needs to be determined.  The correct solder / flux
combination for the wires needs to be determined, etc.........

I prefer crimp connectors over soldering.  The key to crimp type connectors
is to purchase those that are of very good quality and to purchase the crimp
tools that have been manufactured for them.  One of the down sides to this
is the expense of some types of crimp tools.  The Mil Spec tools I use range
in price from $125 to $1,000 each.  Some of these tools will only crimp one
type of connector pin and or socket.  All of the bulkhead style connectors I
use in my IV-P wire harness assemblies are those that are used in commercial
aircraft.  They are environmentally sealed, rated for pressure and are
equipped with gold plated contacts and sockets, so they tend to be more
expensive.  As Brent mentioned, AMP makes some very good connectors and
tooling that is affordable.  The PIDG line of ring and faston connectors is
of good quality.  I use them extensively in all my projects.  A PRO Crimper
II tool can be purchased for around $125.  The connectors and crimper is
available through Allied Electronics or Newark Electronics.  It will crimp
wire from 22 to 10 AWG.  I also use the AMP, CPC line of connectors with
gold plated pins and sockets.  I believe that the cost of the PRO Crimper II
tool is comparable to the one for the PIDG series.  Another thing that is
nice about the PRO Crimper tool that the crimping dies are removable.  You
can purchase one crimper and a multitude of dies, thus saving on the overall
tooling cost.

As I see it, the benefits of using crimp type connectors over soldering can
be outlined like this; soldering is lighter than most connectors.  Soldering
take up less space than most connectors.  Soldering is not cheaper than
connectors because of the extra cost to find the bad solder joints and fix
them.  Soldering is definitely not as reliable as crimp connectors because
of the possibility of incorrect soldering techniques.  I have installed
thousands of PIDG faston connectors and can't recall any failure under
normal operating conditions.  If soldering is the preferred method chosen
for attachment of wires to equipment over crimp type connectors, make sure
that the proper equipment and techniques are initiated prior to soldering.

Happy Building
Bryant Cervens
Panel Specialties, Inc


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