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Author Topic: My build of a "poormans" PowerCON Distro  (Read 8526 times)

dick rees

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Re: My build of a "poormans" PowerCON Distro
« Reply #70 on: January 23, 2014, 10:14:00 am »

The surface area will be big enough initially, but as was mentioned somewhere upthread, solder flows, and the joint will loosen.  Thou shalt not solder wire destined for clamp-type terminals. 

There's no upside to tinning - I have made hundreds of Speakon/Powercon/NEMA/whatever connections with stranded wire, and after about the first 3 plugs, got the hang of it with very few straggling strands.

Tinning is just wrong.  Even when it works, it doesn't...
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Geoff Doane

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Re: My build of a "poormans" PowerCON Distro
« Reply #71 on: January 23, 2014, 01:52:06 pm »

Thanks everyone for correcting my bad habits.  I'll have to go back and check my power cabling.

On a similar note, is it also a bad idea for speakons?

Did you mean actually soldering the wire into the terminals in a Speakon?  We haven't had that debate here for a while, but some people swear by it.  Personally, I've always used the screw connections, and except for some first generation Speakons that came with cap screws that bottomed out before they applied enough pressure, I've had zero problems over the years.  I have seen some Speakons that someone else put together, and they got things hot enough to melt the plastic and misalign one of the pins.

OTOH, I've always sweat soldered the wires onto the NL4MP connectors, and those have held up fine too.

GTD
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Kevin Graf

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Re: My build of a "poormans" PowerCON Distro
« Reply #72 on: January 23, 2014, 02:05:18 pm »

If a Safety Ground terminal unsolder's it's self because of heat a bad situation just got worse!
Is a Speakon terminal unsolder's it's self a bad situation just got a little bit better.
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Lyle Williams

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Re: My build of a "poormans" PowerCON Distro
« Reply #73 on: January 23, 2014, 02:55:29 pm »

Would I pull apart speakons and re-terminate them because the ends were tinned?  Gosh no. 

All my commercially made speakon cables have tinned ends.  They don't seem to loosen up.

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Tim McCulloch

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Re: My build of a "poormans" PowerCON Distro
« Reply #74 on: January 23, 2014, 08:27:08 pm »

Would I pull apart speakons and re-terminate them because the ends were tinned?  Gosh no. 

All my commercially made speakon cables have tinned ends.  They don't seem to loosen up.

Give them time, they will.  Trust me, I'm a doctor... of something... ;)
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Nick Enright

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Re: My build of a "poormans" PowerCON Distro
« Reply #75 on: January 24, 2014, 03:16:56 am »

Give them time, they will.  Trust me, I'm a doctor... of something... ;)
And they loosen up easily over time. There's a difference in the mechanics of the connection when the little metal tab gets pushed against the wire strands, when its a matrix of solder/copper, it's much stiffer and doesn't create the same sort of physical conditions in the joint.

I don't know if this is going to read correctly, but I'm a master metallurgist, and Tim's right. :)

Don't tin unless the connector spec calls for it, exactly how you should build up the connector is called out in very specific instructions on how to make it work best. You disregard these things at your own loss.

(an engineer) and soundguy by practice.

Nick
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Nick Enright
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Lyle Williams

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Re: My build of a "poormans" PowerCON Distro
« Reply #76 on: January 24, 2014, 04:39:36 am »

I understand that clamped tinned wires are not best practice, and are prohibited in some environments.  I'm not sure they are actually banned in AS3000 here or the NEC in the states though.

From my reading, solder shows a 0.01% creep rate per day under 2.3MPa pressure.  That seems significant, but won't creep cause the joint pressure to drop and thus the creep rate to drop?

Clamped tinned wires are very common.
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Nick Enright

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Re: My build of a "poormans" PowerCON Distro
« Reply #77 on: January 24, 2014, 12:00:29 pm »

I understand that clamped tinned wires are not best practice, and are prohibited in some environments.  I'm not sure they are actually banned in AS3000 here or the NEC in the states though.

From my reading, solder shows a 0.01% creep rate per day under 2.3MPa pressure.  That seems significant, but won't creep cause the joint pressure to drop and thus the creep rate to drop?

Clamped tinned wires are very common.

Once you loose pressure/tension in a threaded joint you have failure. Once the solder and copper have moved away from the terminal they start to arc, and go intermittent. Imagine that happening to a Macro-tech 5002vz driving a 2.67ohm load at full tilt... That's basically an arc welder.
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Nick Enright
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frank kayser

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Re: My build of a "poormans" PowerCON Distro
« Reply #78 on: January 24, 2014, 12:06:47 pm »

Once you loose pressure/tension in a threaded joint you have failure. Once the solder and copper have moved away from the terminal they start to arc, and go intermittent. Imagine that happening to a Macro-tech 5002vz driving a 2.67ohm load at full tilt... That's basically an arc welder.

Don't forget now there's a path for oxidation to creep in.  As I understand a crimped connection, it is supposed to be tight enough to be basically air-tight - and therefore no oxidation.

Is a screw terminal that tight?
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Lyle Williams

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Re: My build of a "poormans" PowerCON Distro
« Reply #79 on: January 24, 2014, 01:43:50 pm »

I understand the theoretical failure modes, and why tinned and clamped is not best practice.  It isn't something I do personally - I use ferrules or bare strands.

I'm just trying to get some idea of the expected increase in failures due to this problem.  Tinned clamped wires are common.  Tinned crimped wires are common.  We don't seem to be swamped with failures.
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