Repairing My Headphones: No Sound from the Right Side

Longtime Companion: SONY MDR-CD900ST

SONY / MDR-CD900ST Closed-Back Studio Monitor Headphones

This is a classic closed-back studio monitor headphone that needs no introduction.

According to the purchase history, I purchased it in April 2012.

It seems I’ve been using it for about 12 years.

During that time, I purchased replacement ear pads in 2020 and 2023.

In 2020, I bought these genuine ear pads:

SONY / 2-115-695-01/02 MDR-CD900ST Ear Pads

In 2023, I bought a pair of these. It feels slightly more comfortable on the ears.

YAXI / Studio Headphone DX Blue & Red stpad-DX-LR

However, one day, while working on a track, the right side of the headphones suddenly stopped producing sound.

I learned that this is a common symptom of cable disconnection.

I recalled stepping on or pulling the cable a few times over the years, so I assumed this was the likely cause. I purchased the following to attempt a fix:

SONY / Plugged Cable for MDR-CD900ST

Fernandes / SI-1500 Soldering Iron

Watching YouTube videos, I saw people peeling off the black part of the cable to locate the break, so I decided to try it myself.

However, no matter how far I went, I couldn’t find any break.

I even checked all the way to the plug, but as an amateur, I couldn’t identify anything.

For now, I tried soldering the new cable that had arrived, but the issue remained unchanged...

After further online searching, I discovered that there are rare cases where the cable running from L to R is broken internally.

I don’t recall using the headphones roughly enough to cause such damage, so it was hard to believe—

Or rather, I didn’t want to believe it...

I remembered sound engineers using a ‘beep’ sound to check cables in the past.

A quick online search revealed that this device is called a continuity tester.

I decided to use a continuity tester to investigate, but there were so many types and price ranges that I couldn’t decide which one to buy.

After much deliberation, I settled on this one:

VENLAB / VM-200M Digital Multimeter

Using this, I checked the three colored wires running from the L channel to the plug, and sure enough, all of them produced a ‘beep’, indicating no issues.

Next, I checked the two cables running from L to R.

The red one produced a ‘beep’, but the other one didn’t.

No matter how many times I tested it, it wouldn’t beep...

It seems my issue falls under the ‘rare’ case.

If I could resolve the break in this cable, I could probably repurpose the wires from the old plug cable. However, I lack the necessary skills. While I read that some people fix such issues themselves, I don’t have the expertise, so I decided to purchase the following item instead.

SONY / X-2113-142-3 Replacement Headband for MDR-CD900ST

Once I installed it...

It’s fixed!!

That moment was truly emotional!

Since I didn’t keep track of how the ear parts were positioned, I was worried about whether I had attached it correctly. But when I tested it by panning, everything sounded as it should.

Replacing the headband also improved the fit!

Recently, I had noticed a gap forming under my ears and had been covering it with my hand, but this issue was unexpectedly resolved as well.

I haven’t done a direct sound comparison, so I can’t comment on differences in sound quality. However, the restored snug fit gives me confidence in listening, just like when the headphones were brand new.

Even if there isn’t a break in the cable, if you’ve been using the headphones for about 10 years and feel the fit has loosened, I recommend replacing the headband.

Here are some key points I learned from this repair process:

• A small-sized screwdriver is necessary, not a regular one, for disassembly.
• The screws are extremely tiny, so don’t leave them on the desk after removal—store them in a box or container!
• Take photos at each step of the disassembly process to document how the soldering is done and how the components are assembled.
• When purchasing headphones or cables, it’s a good idea to buy a continuity tester as well. It will help resolve issues faster. (I contacted two local electronics stores, but they didn’t stock any, so keep that in mind!)
• If you’ve been using your headphones for years, replacing the headband might also be worth considering.

I hope this helps anyone who, like me, suddenly experiences headphone failure.

Let’s enjoy the music!

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