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Wire in Stereo Headphones

by cepheid
Tags: headphones, stereo, wire
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cepheid
#1
May3-12, 10:05 PM
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My headphones had a loose connection. I could make the sound cut in and out of the right ear by bending the cable just above the audio plug. So I set about peeling back the insulation. I thought it would be as simple as soldering the broken wire back together. I was wrong for a couple of reasons. Inside the cable, I found three coloured wires: red, blue, and copper. The first complication was that these wires are very small; they didn't fit in my wire strippers, so I know that they are smaller than 32-gauge. Secondly, rather than having coloured plastic insulation with bare wire underneath, these wires appear to have no separate insulation. Instead, the strands themselves are coloured, and they are non-conducting. Is each individual strand coated in something that insulates it?

After scraping at some of the wires with my fingernail, I was able to peel back some translucent white stuff that appeared to be holding the strands together, but the exposed strands themselves still don't conduct, and solder doesn't bond to them at all. It appears that it was not as smart an idea as I first thought it would be to undertake this repair.

How do I work with this type of wire?
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jedishrfu
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May3-12, 10:38 PM
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checkout howto vids on youtube:

http://www.youtube.com/watch?v=N-Lpk...feature=relmfu
vk6kro
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May3-12, 10:42 PM
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It sounds as if the wires have a coating of paint on them.

You can scrape this off with a sharp knife or a razor blade.

When it looks like copper wire, you will be able to solder to it.

cepheid
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May3-12, 11:07 PM
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Wire in Stereo Headphones

Quote Quote by jedishrfu View Post
Hey, thanks, that's really useful! My only criticism would be that it seems super sketchy that he just "repairs" his broken wire by twisting the two ends together and and then covering them with electrical tape, Given the jostling that headphone wires typically get with daily use, I would be kind of surprised if this repair held up for long. Given that I have access to a soldering workstation and some heat shrink tubing, I hope to be able to do better.

Quote Quote by vk6kro View Post
It sounds as if the wires have a coating of paint on them.

You can scrape this off with a sharp knife or a razor blade.

When it looks like copper wire, you will be able to solder to it.
Yeah, in the video the guy mentions that its some sort of enamel, and he actually uses a lighter to burn it off. I haven't decided whether I'll try that, or just go with a razor blade. He also suggests sandpaper.
jedishrfu
#5
May4-12, 12:47 AM
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Twisting wires together is a common method of repair. twisted tightly and they shouldn't come apart easily. Also somtimes soldering can produce cold joints where the connection is still bad or problematic as it might act like a capacitor and attenuate low frequency signals.

Most electricians use wire twists / caps to connect two wires together no solder at all.

The phone company used to wrap wires around posts. They had a special tool to do it. It allowed for easier repair especially when you didnt want to solder them and accidently short two adjacent posts.

Anyway you can still use the shrink wrap insulation if you want but it might make your connection a little bulky.
cepheid
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May4-12, 01:07 AM
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I still think that a solder lap joint is far more reliable IF you know what you are doing, which I will readily concede is a big "if" for many novice hobbyists. However, I know how to solder.

In this context where the joint is going to see a lot of unavoidable mechanical strain, I wouldn't want to rely on the notion that, "twisted tightly, they shouldn't come apart." It would be really inconvenient to have to take off the tape and remake the connection every so often.

The use of wire nuts in household electrical wiring has aways seemed kind of sketch to me as well. It could just be that I'm having trouble viewing things outside of the laboratory electronics/instrumentation context. My fear is probably unfounded, and this type of connection probably more than suffices given the application. Nevertheless, I wouldn't hold up the work of some contractors as shining examples of electrical workmanship.
Bobbywhy
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May4-12, 02:30 AM
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Quote Quote by jedishrfu View Post
Twisting wires together is a common method of repair. twisted tightly and they shouldn't come apart easily. Also somtimes soldering can produce cold joints where the connection is still bad or problematic as it might act like a capacitor and attenuate low frequency signals.

Most electricians use wire twists / caps to connect two wires together no solder at all.

The phone company used to wrap wires around posts. They had a special tool to do it. It allowed for easier repair especially when you didnt want to solder them and accidently short two adjacent posts.

Anyway you can still use the shrink wrap insulation if you want but it might make your connection a little bulky.
Oh, Cepheid, don't let information like contained in the above post misinform you!
1. soldering is the only correct sure way to repair your audio cable.
2. cold solder joints are caused by incorrect, improper techniques done by incompetents.
3. electricians use "wire nuts" specifically designed to cut into both conductors and form a tight connection...very different than simple "twisting two wires tightly together".
4. telephone copper wires do get wire wrapped around posts, but those posts have sharp, square edges which cut into the wires to insure a good connection AND also form a gastight seal...otherwise the dissimilar metals would corrode and cause resistance.
vk6kro
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May4-12, 02:36 AM
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I use wire wrap sometimes, but I always solder it as well because I don't trust it.

A razor blade is good. You just lay the wire on a flat surface , scrape it and then rotate it a bit and scrape again.You will see when it is properly clean.

A flame just oxidises the metal and makes it harder to solder.

Sandpaper is OK for large wire, but I find the fine wire seems to slip between the gritty bits on the sandpaper.
AlephZero
#9
May4-12, 08:11 AM
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Wire wrapping and insulation displacement connectors (IDC) can be more reliable than soldered joints, but only if they are made correctly with the right tools for the job. Soldered joints that are repeatedly flexed (as in a repair to a flexible cable) often break at the end of the soldered region, because the bending causes a stress concentration at that ponit and/or the soldering temperature changes the metallurgy of the wire.

But "twisting very thin wires together and wrapping some duct tape round the outside" is defintely NOT a properly made "wire wrapped" joint!

The most reliable way to repair this would be replace the whole cable and re-solder it onto the headphones themselves, but that is often impossible with "cheap" headphones because they are not designed to be taken apart and re-assembled.
jedishrfu
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May4-12, 10:48 AM
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Where's macgyver when you need him.
dlgoff
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May4-12, 04:42 PM
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I learned this technique a long long time ago.



Western Union splice
cepheid
#12
May5-12, 01:23 AM
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Thanks for all the input guys. The discussion of the pros and cons of various electrical connections is always relevant and interesting.

In the end, I found that the problem was with the connector itself, so I snipped the old one off and bought a new 3.5 mm audio plug for $0.95. I soldered the wires to this, applied some tape for insulation and strain relief, and then closed it up. I'm happy to say that it has been working just fine for a good 6 hours already now.

We'll see how it holds up. On the bright side, with a connector housing that threads open for easy access, at least now repairs will be convenient in the future. The connector that came with the headphones was fully enclosed in soft plastic/rubber that was moulded in place or something.


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