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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Installed Sound/Contracting => Topic started by: Merlijn van Veen on November 21, 2013, 08:59:53 am
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I have a Kramer Electronics device that I need to connect. In the rear it has green terminal blocks containing screws with metal plates. What is the best way to connect the cables (AWG 26 - 14 mm2)? Tinning seems to make the cable fragile, which leaves crimping terminals or nothing at all. What's best practice in terms of reliability and signal quality (line level)?
Sincerly,
Merlijn
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I don't see why tinning would make the cable fragile.
Steve.
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I don't see why tinning would make the cable fragile.
Steve.
From what I've come to understand, the cable is more likely to break and the mechanical fastening of the connection comes undone/loosens because the solder apparently shrinks/deforms over time.
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For the green terminal blocks you would typically not want to do anything, no crimps and no tinning. Just gently twist the bare strands together, insert into the appropriate terminal and tighten down the retention screw, making sure you make contact with the conductors and not the insulation.
Yes, under constant pressure the solder may flow and a connection eventually come looose.
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+1 for bare wire. As you screw down on a bare wire the strands will spread allowing for a tighter clamp. Not only have I never had any issues in installs, I've been using Driverack 481s, which use those Phoenix connectors, in my live rigs for years and have never had an issue with the wires coming loose.
Doug J.
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I was starting to suspect as much. Thanks for the input!!!
Merlijn
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There are two problems with solder-tinning the end of a stranded wire for use under a screw terminal.
a] With time and temperature changes, the solder-tinning will cold-flow allowing the terminal to loosen.
b] A hard spot will be created at the end of the tinning. Continued wire flexing can cause a break at that point.
Industrial & military systems often use ferrules.
http://www.ferrulesdirect.com/
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There are two problems with solder-tinning the end of a stranded wire for use under a screw terminal.
a] With time and temperature changes, the solder-tinning will cold-flow allowing the terminal to loosen.
b] A hard spot will be created at the end of the tinning. Continued wire flexing can cause a break at that point.
Industrial & military systems often use ferrules.
http://www.ferrulesdirect.com/
This is referred to as "solder creep". ANd to think of it another way. A solid piece of wire is much easier to ben back and forth and break than stranded wire of the same gauge. The solder will tend to turn a stranded wire into a solid.
Of course if the wire is not moved-this is not an issue.
But the crimp will tighten down much better with the bare wire than the soldered and the stranded wire will provide more contact area with the connector than the soldered wire.
But the soldered wire is easier to install.
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Use the proper gauge wire for the terminals.
Use a quality wire stripper.
Make lite use of a quality linesmans' pliers to twist wire end.
Insert and tighten.
Tinning the ends violates the engineering maxim : "Always Add Simplicity".
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Use the proper gauge wire for the terminals.
Use a quality wire stripper.
Make lite use of a quality linesmans' pliers to twist wire end.
Insert and tighten.
Tinning the ends violates the engineering maxim : "Always Add Simplicity".
Good list but I would add not to crimp too short or insert too far so that you end up compressing on the insulation rather than the conductors. Many times I've had to loosen and just lightly pull out such terminations, then retighten them, to get a good connection.
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Linesman pliers are probably just going to ruin 26 AWG. Thumb and index finger are the better option.