Sunday, April 7, 2013

Repairing Broken AKG K240 Studio Headphones

Christian over at Black Sunshine Media (Wait, you don’t know about Black Sunshine Media? Get over there and check the site out immediately. It’s awesome.)

Anyway, what was I saying? Oh yes, Christian over at Black Sunshine Media asked if I could possibly fix his headphones, since they were his favourites and an essential part of his kit. He showed me this photo:


I think the technical term for what happened here is that they “assploded” (through no fault of their own, I might add). According to Christian, they got a bit squashed at some stage.

Anyway, I took one look at the wires and said something entirely too self-confident like “piece of cake”. In fact, the wiring was the easy part. Figuring out how to put them back together took a bit more, well, figuring out.

Before continuing, the other wire is disconnected to make things easier to work with:


It didn’t even dawn on me to take a photo at this stage, but the next step here was to put the back of the pad back on. This wasn’t rocket science and no tools were required. Here’s how it looked after doing that:


Next was to figure out how the whole thing was going to go back together. Actually it’s a very clever mechanism. Basically (excuse me for going all engineer on you again), it works on a universal joint principle. This is what a universal joint looks like. Your car has several. This joint basically allows for freedom of movement along two axes, while maintaining a positive connection along the third.


(Image taken from http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia/Universal_joint)

And that is what allows the pads on each side of these headphones to move a little bit to fit the angle of your head, without actually falling off (yes, I appreciate the irony that these ones actually HAVE fallen off, but that wasn’t technically supposed to happen).

Anyway, the little joint itself, which just to clarify, is this:


Was still connected to one part, but not to the other. The problem is that there was no way to connect it to the other part while trying to fit the headphones together, because you just can’t get your fingers (or any tools) in there to position it right, while simultaneously closing everything up.



But if you look closely, you can see that the part it is already connected to is specifically designed to assist with this exact thing, i.e. it helps correctly position the joint as you are closing things up.


Wait, that's a bit hard to make out. Let me remove it slightly so you can see a bit better. Imagine you need to push that circular bit down. You can see that there is a bit of a slope guiding it into place. See it?


So what we do here is take the joint out completely and connect it to the OTHER part (the one that is just too difficult to connect to while we’re trying to close everything up). Just squeeze the joint together a little, which will make it narrower while you move it into position.


Note the little tapered edges pointed out below. Make sure they are facing out the way, so that they can interface with the sloping guide mentioned previously when it comes time to put it all together.



Then we quickly add a couple of little extensions to the wires, since the red one in particular is dangerously short and I’d hate for it to snap again.


I’d usually put heat shrink tubing over this, but I don’t want to apply heat anywhere near the pad covers, so I’m just using PVC tape instead.


And we solder the wires back in place:


Now we carefully position things so that everything is lined up right and the joint will clip nicely into place (on both sides) as we close this up.



"Persuade" it into place with a flat-head screwdriver:



A nice click is heard, the world rejoices and we’re done.


Piece of cake (kind of).

5 comments:

Christian Adams said...

Much appreciated, Stu! Awesome article and how-to. I still don't think I could pull it off, but at least now I know how that stuff works!

Alex Alpert said...

Nice work. Just fixed mine. Totally right about installing that piece on the ear piece and then putting it back together. Using the flat head to get it back together was dicy.

stu said...

Nice one, Alex. Glad it worked out for you.

Anonymous said...

How do you know where to put the red wire and where to put the white one? Don't want a phase inverted speaker on one side...

Nikto 24 said...

Sorry for the late comment, but I have to post this anyway: you probably didn't know that you had to tie a knot between the wires — check this out here: http://cloud.akg.com/10909/k240studio.pdf I know — you'll have bad dreams this night, he he (evil laugh).