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Neil Sherman

Cos11 Re-terminating

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In my old staff job I used to repair a lot of cables.  I'm starting to get pretty good with the more fiddly jobs, small connectors etc.

 

However, like many, I struggle with the litz type cable that COS11's and other lapel mics are made from.  I feel like i'm soldering bits of plastic.  Specifically the black wire in the mic seems to have a strand of strong nylon in the core, that remains when the copper strands seem to be burnt away during tinning.

 

I'm not expecting a simple solution to this, but i'm going to master this skill even if it kills me.  Can anyone advise on the best solder and temperatures to use whilst tinning and terminating this stuff.  I've tried temparatures from 360 - 450 degrees celsius and my success seems to be more luck that judgement at the moment.

 

I'm using lead solder, burning off the insulation, rather than scraping it off and putting a dab of pen flux on the connector contacts.  Any suggestions? Please don't tell me to send it to a pro wireman, i'm trying to become one!

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Hi Neil,

There are various methods, each to their own.  But here's one that works.

Turn iron up to max temp - apply a large blob of solder to the iron tip.  Push the unstripped core into the blob - with the right technique and timing, the inner conductor will tin and the jacket will shrink back. 

Takes a bit of practice but it does work - there is a technique to it that doesn't come without a lot of practice (save your offcuts for said practicing).

re: the other stuff about expensive tooling, If you meant your comment about becoming a pro wireman (as in wiring for others, not just your own stuff) it's a necessary step to buy a lot of specific, expensive tooling, often for just one purpose.  You'll also have to do away with lead solder if you want to be ROHS compliant here in Europe.

best of luck!





 

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The wires have a coating on them similar to headphone wiring. Search the interweb for videos "how to tin headphone wires" multiple great tips.

 

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It's best to use small scissors or very sharp dikes to cut away the yellow kevlar fiber. Then turn the heat up to 11 and touch the tinned soldering iron tip to the cut tip of the enameled conductor. When the solder flows onto the raw copper tip of the wire, it will burn off the enamel insulation, at which point you can tin the rest of the wire tip. It needs to happen fairly fast, but that's how it's done. 

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1 hour ago, John Blankenship said:

Pretty much what Glenn and others have offered.  I will add that the critical element that makes one good at this echos the well-known response to, "How do I get to Carnegie Hall?" 

Taxi?

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It would need to be a plane trip for me!  (Have heard the expression btw)

 

Cool.  I'll practice with the above cheap option until either:

 

a. the mic is 50cm long and then i'll send it off to a man who can (don't know any women who can yet)

b. get it right

 

Then i'll look into buying the bits when i'm a bit more flush.  I'm well up for practicing this a lot. 

 

PS. Don't tell anyone about the lead in my radio mics.

Thanks folks!

 

N

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On 9/25/2018 at 3:07 PM, John Blankenship said:

Pretty much what Glenn and others have offered.  I will add that the critical element that makes one good at this echos the well-known response to, "How do I get to Carnegie Hall?" 

 

For those who don't know the old joke:

 

A tourist walks up to a New York local and says, "Excuse me sir, can you tell me how to get to Carnegie Hall?"

 

The local replies, "Practice."

 

And thus it applies to soldering technique. 

 

 

1 hour ago, Neil Sherman said:

Also i'm going to have a very careful google search about what dikes are.

 

Diagonal cutters. 

 

For this kind of work the best choice is the thin version called "lead cutters" or "flush cutters." I call them "nibblers" but may have made that one up. 

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I used to never be able to afford a taxi so I always took the train (subway).

 

Yep, put the wire in a blob of hot solder and the enamel will burn away.  It does take practice but works well.

 

My favorite dikes?

Xuron Micro-Shear® Flush Cutter with ESD Safe Hand Grips

Not expensive.
 
D.

 

Xuron micro.jpg

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I solder them to Lemo 3 pins for Zaxcom. My trick is to forgo tinning the Sanken leads...... I fill the solder cup of the connector with a healthy amount of solder then dunk the wire deep into that pool. The jacket melts away and you are left with a connection. If you need more solder brace it with helping hands and add more.

 

Second trick with lemo 3 is to cut some of 3x5 card and wedge then between the pins to isolate them while working.

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