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Can't get solder to stick


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Try waving a lighter under the strands for just a second until whatever coating ignites, then sand, then tin.

This. Sennheiser like to incorporate fine strands of...something (polyester?) into their wires, presumably to make it difficult enough to repair that you'll give up and send it back (for a fee) or buy a new one. I've never had to sand, just burn up the fine strands with a lighter (helps to fan out the wires a bit first) then tin and solder as usual.

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It's not just Sennheiser. Sony, Countryman and many other lav manufacturers use the same type of mini stranded cable with "Litz" type coating as insulation. You have to burn off the coating as Justin said above. One point of note. The seperate packs of wires are color coded i.e.: red & green, white & black, etc. Burning the coating off also removes the color code so be sure you note which was what color before you solder on a new connector so you don't have to do it again becauseyou forgot which was positive and which was negative. Been there done that.

Eric

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Litz wire is a tinsel stranded wire. It is very rare to find it nowadays. It's great advantage was extreme resistance to flexing for jack cords etc. You never could solder it - it was terminated using crimps.

The more usual trick that some manufacturers use is to enamel coat the wire as an insulation - though I'm not sure that Sennheiser have ever gone for that. To solder that you need a high temperature and a way of wiping the gooey residue off the wire as you tin it.

An "old" MKE2 sounds suggests the core strands might have oxidised a great deal. In that case the solder flux might have to be quite aggressive to cut through the oxide layer be able to wet the bare metal.

If there is significant "greening" of the cores that may indicate a lot of reaction with sweat through the PVC sheath. In that case you might find that the strands break up very easily even if you can finally get solder to "stick".

Chris Woolf

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even more, the Senn MKE-2's used steel wire, very difficult to solder properly without the proper equipment and techniques.

be careful of using too much heat, and possibly damaging the insulation...(both the wire and the connector!)

" presumably to make it difficult enough to repair that you'll give up and send it back (for a fee) or buy a new one. "

oh, grow up... >:(

the wires are carefully and specifically selected to be thin, strong and flexible, even including thoughts about noise conduction.

Edited by studiomprd
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And forget about that lead-free solder. I can't use that stuff.

That's the RoHS type of solder. You can't mix it with the normal lead based solder. Basically it sucks. Buy a couple of standard 8oz, .032 diameter rosin core 60/40 or 63/37 rolls at Radio Shack and you'll be set for years.

Eric

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Thanks for the tips, tried the lighter and sandpaper and it didn't work on these. I've now managed to kill the lemo connector :/ I bought it from Sennheiser, so I don't think they have a problem with other people rewiring their mics.

They look like steel wires- might try someone else if you need different tools for the job (what are they?)

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Litz wire is a tinsel stranded wire. It is very rare to find it nowadays. It's great advantage was extreme resistance to flexing for jack cords etc. You never could solder it - it was terminated using crimps.

Doh, I think all the Sony headphone cables still use Litz wire. That stuff is a nightmare to solder. Lots of "audiophile" cables (Monster, etc.) also used Litz design wire, with each strand coated with a laquer-like coating. I have bad soldering nightmares from the late 1980s and early 1990s, trying to solder Monster Interlink 100 wire for a patch bay with about 75 terminations.

It's for reasons like this that I don't miss a lot about analog, especially for consumer audio applications...

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Ah, so that's why my cos-11 wire was so hard to solder! I wasn't sure if those little strands were supposed to be stripped away or not. Had a hell of a time trying to get a solid solder joint going. I tried to so many times I think the heat eventually melted away the strands and took hold. Now I know for next time.

Learn something new here every day.

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