how to wire headphone jack with three wires.

[risong]

Hi,
I have a set of Shure earphones that act up at times. I am quite sure
that the problem lies in the jack. My question is there are 3 leads. I
have bought a new jack, but I really do not know where to connect these. I
tried a local TV repairman and he said he didn't know. The original Shure
jack is molded and I cannot just follow the wire. I've searched on Google
for a wiring diagram. These are quite expensive earphones and I don't want
to mess them up by guessing.
Any suggestions?
Thanks in advance

 

[Don Taylor]

"risong" <risong@cox.net> writes:

I have a set of Shure earphones that act up at times. I am quite sure
that the problem lies in the jack. My question is there are 3 leads. I
have bought a new jack, but I really do not know where to connect these. I
tried a local TV repairman and he said he didn't know. The original Shure
jack is molded and I cannot just follow the wire. I've searched on Google
for a wiring diagram. These are quite expensive earphones and I don't want
to mess them up by guessing.
Any suggestions?
Thanks in advance

Stereo jacks have 3 connections, one for "ground" that both the audio
channels connect back together to return to your source, and one more
for each half the headphone, each ear. If you look at the plug on the
end of your earphone cable you should see the long silver tube closest
to the cable end, that's the ground, and when plugged into the jack
there is a little metal contact finger that touches this to give you
the ground connection. Closer to the tip you should see two separated
metal sections, with a little ring of insulation separating each of
these from the other. One of those sections will be the connection
for each ear. (Mono plugs only have the tube and one section, because
they only need the ground to get the signal back and one wire to get
the signal out to both earphones that are connected together)

So, it sounds like you believe there is an intermittent connection
between the headphone cable and the plug itself. And that you are
thinking about cutting off the old plug and trying to solder on a new
one. When you cut the cable off the old plug and look at the end of
the wire it might be pretty small but you should see three groups of
wire, one for the ground and two for the earphones. It is possible
that one of the groups of wire is going to be a sort of sheath or
coating of lots of fine wires that are wrapped around the outside
of the inner two insulated wires. That's called "shielding" and the
outer layer of wire is supposed to help keep electrical noise away
from the inner two wires. If that is the case then you can be pretty
sure that outer coating of fine wire is your ground. And that is to
be connected to the long tube at the back of the plug, away from the
tip. Hopefully the plug you bought had a little diagram of the
connections on the package so you can see which of the three
connectors on the back end of the plug connects to the tube portion.

Now, The other two wires, one is for one ear and the other is for
the other, but which is which. Well, if it isn't really critical
to you whether the left "channel" on your stereo goes to your left
ear or to your right ear then you could just hook the two remaining
wires up to the two remaining connections on the plug and be done.
But if left and right really matters to you then you probably can't
tell, just by looking at it, which wire should connect to which
connector. You could try soldering it, check to see if it is right
and if not then reverse the two wires.

Soldering, these are likely going to be pretty tiny fine wires.
Having a little practice with a soldering iron helps a lot. And a
soldering iron that works well helps. Plus some "flux" that looks
a lot like grease, but isn't, that helps get the solder to melt onto
the wire and make good connections is essential.

Since the headphones are expensive I'd suggest a trial run. Find the
cheapest junk stereo headphone around and sacrifice them for practice.
Cut the plug off them, compare what you see to all I've written, do
the soldering onto the plug you bought, plug it in and see if it works.
Once you've done that then repeating it with the expensive phones
should be less daunting.

Ah, when doing the final job, don't forget to slide the little plastic
screw-on cover for the plug onto the wire BEFORE soldering the wire
onto the plug. Otherwise you have to live with it being open and bare
OR you have to unsolder the whole thing, slide it on, and then solder
it back together. Not that I've learned that the hard way before.

I hope this helps. If you have more questions then throw me email,
my address is valid.

 

[loedown]

Hi All,
Your local TV repair man should know, or he couldn't be bothered
doing it for you.

3 wires, one should be red, one should be white and the other will either be
a braid, or black.

black / braid = ground, connect this one to the rear section of the new
phono jack

red = right signal, goes to middle section of the phono jack connector

white = left, goes to the tip of the phono connector

maybe the tip is right and the middle section is left, but armed with this
info you should be able to resolve it now for yourself.

Just one handy hint, have the amp off when you are ready to test the
headphones, and at minimum volume. Plug in the headphones, turn on the amp
and slowly turn up the volume to around 1/4 of the way, if you hear nothing,
something is really not right and use balance to check that left and right
are correct.

Paul