How to fix headphones?

Factual Questions
1

So I just got a pair of broken headphones from a friend of mine who is tired of trying to get them to work. They are Kenwood headphones that have a line going into one speaker and then a wire running across the top to the other speaker.

I took apart the side where the line enters, and found that the speaker is not connected to the wires. I stripped the line in, and found that there are 3 wires inside: red, blue, and gold. Inside the one ear there are two wires that leave to go to the other speaker: red and gold.

The speaker itself has four dots of solder on a little board right next to it, so I assume that the wires need to connect up there somehow. However, I have 5 wires and only 4 spots and there are no markings that I can see on the little board.

Can somebody tell me how to fix this (ie. which wires need to go where) or direct me to a site where I can learn some basics about audio circuits in headphones.)? Also, is there an easy way to test it before soldering it back together?

2

since no one is biting, i’ll try:

(disclaimer: i know i can fix em if i had in my hand, but talking or typing you through this may be beyond my meager skills…)

assuming these headphones are indeed stereo, i would first determine which wire is ground.

eyeball the plug that goes into the stereo. you will see it has a knob shaped thing on the end, and two little plastic rings. this seperates the ground (-) contact from the right and left positive, or power contacts.

test continuity from the very end of the plug to the blue, red and gold. it should only read on one wire (guess= gold because red is most often used as “hot” and one of the red or gold coming from the other side has to be negitive).

double check by checking the red and blue wires to the small band on the plug (seperated by a small plastic ring). the two remaining wires (guess= blue and red) are going to be “left” and “right” channel positive.

okay so far? good! plug in the cord (dont let the wires touch each other) and using the negetive and one positive wire (right or left, dont matter) touch them to the speaker. try the various combinations till you get sound. the other side will connect up as follows: the negitive (we assume gold at this point, but could be the red) will hook up with the same color wire as the first speaker. the remaining wire will go on one of the other spots (two remaining). one spot will remain open. in other words, the blue will go to positive terminal on one speaker, the red to the red wire on the other speaker and the golds all go together. (how this coralates to the “little board” is up to you to figure out. if you omit it and just hook the wires up directly, it should work.

best i can do without lookin’ at em! your description of the “little board” confuses me a bit.

well, the good news is, even if you short these wires out testing, your not gonna get hurt or damage much. if all else fails, mail em to me and i’ll give it a whirl!

good luck! (tools required== cheap multimeter that reads continuity, soldering iron)

3

By “Gold” I assume you mean bare copper?

The wires should be:
red: right
blue (sometimes black, etc.): left
copper: common.

As for the 4 points on each driver (not speaker), try this: get a 1.5Volt battery and attach wires to it. Lightly brush the wires to pairs of possible connection points next to the driver. Listen for clicking sounds. The loudest click is probably at the best places. If neither wire at the places you choose are otherwise connected to anything big/metalic, it won’t matter which goes where as long as you’re consistent on both drivers. If one point does connect to other stuff, make that the common.

Once soldered on, then use the battery to test the connections at the plug. The tip is common (and of course I can’t recall offhand which of the next two is left or right. And it’s only been 4 days since I done this test on some earphones myself.) Make sure you get clicks in only one side at a time.

If each 'phone has two drivers, then you’ll have two pairs to solder to on each side. Keep things in parallel.

Once it tests ok, try out first on some piece of junk equipment you don’t mind losing. (Like that one piece 8-track/phono/tuner your mom bought in the 70s.)

(And gatopescado posts just a little faster.)

4

The “little board” is a small piece of the same kind of plastic they use to make circuit boards out of. It is brown and has 4 contact points on the side I can see. I cannot see the other side without ripping apart the driver (=speaker?). I assume that it has some path to the speaker itself.

The headphones are stereo; I can see the stereo on the mini-jack, and the two sides are labeled right and left.

A coupla more questions, and thanks for being so helpful so far. I think I know what I have to do…

The wires are not insulated individually. Inside the rubber cord, the three are just next to each other. The colors are… in the metal itself, not the color of the insulation on each. I would think that this would cause a short, but it doesn’t seem to…

gato, am I to understand that I can just touch the wires themselves to the speaker to make a connection? Is the “little” board just so the ground can run through both speakers?

Is there anything that would suggest that the headphones will not test out until all the wires are connected? In other words, do I have to hook up the other side so that I have a complete circuit?

5

I just tried to run some current through the wire to run a flashlight, and I got no light at all. Does this mean that the cord is bad?

6

hummmm…strange. i’ve never seen a little circuit type board in any headphones, but then again, i have only dealt with cheappy-throwaway stuff. as for the wires, sometimes i have seen this wierd fiberglass-like strands used in headphones for the connection wire. i have never been able to reconnect those type wires. they are very thin and tend to melt when solder is applied. they have appeared to be colored internally with no visible insulation like you describe. this maybe what your seeing. in cases like this, i abandon the orig. wire and hit the radio shack and just make my own wire and plug. (i hook up stereo headphone systems in motorcycle helmets with integral volume controls and quick disconect systems, so i rarely use the original wiring anyway)

as long as you are getting continuity through the wire, they should run the speaker, they may not be able to power a flashlight bulb, so that is not the best test. you can touch the bare wire to the speaker terminals without soldering them to test (i think that answers your question)

the guy who posted just after me sounds like he is better at this than me, so i would use his advise on testing!

good luck!