Recabling Sennheiser HD 457 Headphones
I purchased my first pair of Sennheisers around five years back and they served
me well for the time I've owned them.
Until this week.
One side of the headphones stopped working all together. If I moved the cord just
right, the other side would cut out as well. So, It's time to disassemble them and
repair the cord.
Here's how I repaired my headphones.
- Sennheiser HD 457 Headphones
- #1 Philips Screwdriver
- #1 Straight Blade Screwdriver
- Heatshrink Tubing - 1/8" and 3/16"
- Soldering Iron
- Desoldering Braid
- 6' Stereo Extension Cable
Step 1 - Disassembly
Start off by popping of the earphone covers. They come off with a little pressure
around the edges. They secure to the gray plastic housing with two plastic hooks
and with a little pressure, they release their grip.
Step 2 - Seperating the housing from the headband.
My headphones were pretty well warn so this next step may be a little easier for
me than you. The gray plastic housing secures to the headphone band with a ball
and channel. The ball is on the housing and the headband contains the channel. If
you slide the housing up to the top (like sizing them for a very small head) there
is a small v-notch at the very top of the channel. Gently pull the the headphones
straight back from the headband, all the time supporting the headband with equal
pressure backwards. They should come out fairly easily. You need to pull straight
back or else you'll break the ball off, rendering the headphones useless.
Repeat the process again for the other side. You should have the headphone housings
seperate from the headband now.
Step 3 - Removing the drivers
There are four Philips #1 screws that hold each driver in the gray plastic housing.
Take a small jewelers screwdriver and unscrew the four screws, being careful not
to lose them. Now the driver should come out if you tip the gray plastic housing
Step 4 - Seperate the drivers from the housings
This is where the drivers and housing part their respective ways. First take note
of which wire goes to which terminal. I took a continuity tester and mapped out
which was the signal and ground wire from the jack. My signal wire was attached
to the terminal with a number above it and the ground was the terminal with no markings.
As a note, the signal wire is colored red or green.
Move the foam layer away from your working area. Hot soldering irons and this layer
don't mix well. Take a soldering iron and desolder the two wires from the driver.
Clean up the factory solder with desoldering braid or a desolder iron. Set the driver
aside. We're going to be working on the housing next.
Step 5 - Removing the wire from the housing
There is a small metal U shaped piece of metal that holds the strain relief boot
and wire to the terminal. I ended up using a small flat bladed jewelers screwdriver
and a fine tipped pliers to remove the piece of metal. Set the part aside.
You should now be able to wiggle the strain relief boot and wire out of the housing.
Separate the two and set the housing aside. We are now going to be separating the
strain relief boot from the wire. Take a scalpel and cut the boot lengthwise down
the middle, exposing the wire and a metal clip. The wire is glued into the bottom
of the strain relief boot. I ended up taking a fine tipped pliers and pulling out
the insulation from the wire. After you are done, you will be left with a strain
relief boot to be used in the upcoming step.
Step 6 - Adding new cable
Cut the female end off the stereo extension cable. The next step is to separate
the cable to go to each housing. Split the cable 14" - 18" from the end. The distance
is up to you, base it on personal taste for how you want your headphones to feel.
Slip a piece of heat shrink tubing over both wires now. This will be how you stop
the wire splitting further than you need it to at a later step.
You're wire will have a coating over the pair of internal wires. Strip 2"-3" off
the wire pair, exposing the grounding layer and internal signal wire. Next, twist
the ground layer strands into a wire. This makes wiring a little easier. Finally,
strip 1/2" of insulation from the signal wire and twist the strands. It makes the
next step easier.
Place another peice of heat shrink tubing over both wires here. This keeps the strain
off the wires for the next step.
Step 7 - Tinning the wires and replacing the strain relief boot
Take the wires that you just twisted and tin the ends of both wires. This step is
a lot easier when the wire is free of the housing as space starts becoming tight
in the next steps.
Next we are going to place the strain relief boot on the new wire. I slipped a piece
of heat shrink tubing on the wire to be used to secure the strain relief boot to
the wire before putting the boot on the wire. Open the cut your used to remove the
strain relief boot from the wire and slip the wire into the cut on the boot. The
boot should end up 2"- 2.5" from the end of the wire, with the square end facing
the bare wires. Slide the heat shrink tubing over the boot and shrink closed. This
will keep the boot from moving on you and secure the wire and strain relief boot
together for the next step.
Step 8 - Hooking up the wire to the driver
Slide the wire and strain relief boot back into the gray plastic housing. It takes
a bit of wiggling to get the locking channel past the housing. When you have the
wire aligned and positioned back in its original spot, place the metal U shaped
retaining clip back on the gray plastic housing with a fine tipped pliers. You should
now have the wires, strain relief boot and housing all together now.
Take the driver and tin the two pads that you cleaned off in a previous step. This
makes the next step easier. I used a third hand to hold the wire and held the driver
in my hand in the next step. Solder the wires back to their respective terminals.
I chose to leave the foam layer off up until now. Slip it back over the driver and
connect it back in the orginal spot. There is a notch in the foam and a raised notch
on the gray plastic housing. Align them. Screw the driver back into the gray plastic
housing and reattach the headphone pad that your removed in Step 1.
Congratulations, you now have 1/2 of the project complete. The process is the same
for the other channel when you have both of them rewired, snap them back into the
headband. You are now finished. Plug them in and test them out and you should now
have a working pair of headphones. If you notice that they do not work, check your
solder joints. You either have a short or a cold joint. Reheat the joint and check
I did find out why the headphones failed during this project. Sennheiser places a metal clip around the cables under the strain boot and the place where the two wires split to each ear. This breaks the wire over time. See photo for the offending part.