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I've never seen this malady on an XLR before. How did this XLR (from a rack de-install) get that hot? Or is this even from extreme heat? 

Anyone ever see this before? How strange. 

image.jpeg

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That might have happened when the connector was soldered to the cable?  Like iron way hot?  That doesn't look like a Switchcraft or Neutrik part, and I have found pretty suspect metals used in brand-x XLRs, that discolor etc.  You may also have noticed that the plastic insert that holds the pins on cheap XLRs can melt if you apply much heat to the pins, which results in the angles and spacing of the pins getting distorted--they can even sink back into the plastic, becoming too short to make contact.  (Learned all this the hard way.)  On the cheapo connectors it seems to be important to make the solder very quickly, thus.

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That was my first thought. But the connector shows no sign of heat, otherwise. You'd figure, to discolor the pin would take such heat, that even a Neutrik connector might melt and slip the pins. It was crappy three conductor Mogami cable (with silk stranding in the copper) on the offending character (and a few others), Star Quad on the rest of them, but I can't see THAT as a cause. Baffling. There were fifteen or twenty XLR's (m and f) in this rack. Others show tarnish but not that 'rainbow' effect like extreme heat does to some metals. And the solder joints were all very nice, I.E. a pro installer made them up. This might even baffle a metallurgist. Go figure  : /

 

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I have seen this before and have actually done it myself without melting the plastic.

I don't remember exactly what it said, but in reading the Neutrik pdf on their connectors, the plastic is rated for some insane amount of heat.

Sent from my SM-G935P using Tapatalk

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Okay. Running my soldering iron at 720 degrees (the usual setting), I only had to hold the iron to the cup approximately 20 seconds before it slipped pin 1 (pic 2).  I checked it again on pin 2. Bubbling nylon coming out of the cup side of the insert at 23 seconds.

But look at the first pic. Discolored somehow, yet no sign of melted nylon. Still a mystery. 

Before the test (pic 2), I was ready to increase the temperature to X (much higher), but there was no point in that.

Still baffled, and we may never know. 

image.jpeg

image.jpeg

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If you go to NAB this year, take the connector with you and see what the Neutrik folks say.  I wonder if it's possible when that particular insert was fabricated it met with more heat than it should have.

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Using .032 diameter 60% rosin core solder will eliminate any heating issues. The smaller diameter heats and flows faster than larger sizes. I use the basic Weller soldering set up with the temp knob set at #4. I don't know what temp that is but it works perfectly at that setting. Since it's not broken I don't try to fix it.

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On March 11, 2017 at 10:02 PM, John Blankenship said:

If you go to NAB this year, take the connector with you and see what the Neutrik folks say.  I wonder if it's possible when that particular insert was fabricated it met with more heat than it should have.

That sounds like a good idea. 

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On March 10, 2017 at 11:54 AM, Rachel Cameron said:

Okay. Running my soldering iron at 720 degrees (the usual setting), I only had to hold the iron to the cup approximately 20 seconds before it slipped pin 1 (pic 2).  I checked it again on pin 2. Bubbling nylon coming out of the cup side of the insert at 23 seconds.

But look at the first pic. Discolored, yet no sign of melted nylon. Still a mystery. 

Before the test, I was ready to increase the temperature to X (much higher), but there was no point in that. The offending character shows no sign of melting and yet, still rainbow discoloration. Still baffled, and we may never know. 

image.jpeg

image.jpeg

 

Twenty seconds is WAY too long.

It should be 2-4 seconds.

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Traut is correct, less than 5 seconds is more than enough to melt the solder and get it to a liquid state. Tin the connector cup first then tin the wires then melt them together. The images show way too much solder being used in each of the cups which is probably why you have heat discoloration on the pins.

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One thing you might have encountered is that the pins are oxidised and therefore will not hold the wet solder until it gets hot enough for the oxidisation to give way. Use of a good flux (gel) is recommended in this case, or you could "sand" off the oxidisation. 

Oxidisation also occurs on the soldering tip. Best way to deal with this is to keep cleaning the tip on the brass wool and retinning the tip many times until the solder melts instantly and covers the tip. 

Definitely not more than 5 to 7 seconds should be needed to melt the solder both on the pin as well as the cable. 

 

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That's just oxidation. Not heat. If that was heat, it would have melted the insulation on leads to pins 1-3. Same kinda coloration happens to collectable coins. Your maybe thinking about annealing (used to strengthen rifle brass). You could try some contact cleaner and some Cpap smear swabs ( little brush on a stick) and scrub it. Try a wood qtip for extra strength if needed. Stay away from steel wool, and sand paper, try to solve the issue chemically.

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That explains a lot. Very reasonable that it would be oxidation. In the thread here, I began wondering about the manufacturing process, and if the pins go through the annealing (thanks for the term) process before they get a thin coat of silver (?) and pushed into the nylon insert. I'll try some Deoxit or the CRC QD Electric Contact Cleaner. Thanks so much, Auxbusreturn.

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