Easy Guide to REPAIR Broken BOSE QC25 Headphones - NO SOUND From One Ear

Bose is well known for their headphones, and more especially their active noise cancelling lineup. The first time I put a pair of QuietComfort 35's on in an electronics store, I was blown away by the silence they can create. However, I had a very little budget I wanted to spend on another pair of headphones that I would use only occasionally when travelling. So I began looking for Bose headphones on second-hand websites. I found a pair of QC25's that had a broken right side speaker and bought them from the auction for only 15€. The problem of blown speakers seems to be a common problem with the QC25's. So, here's a tutorial on how to fix your broken pair of headphones saving money and the planet by the way!

Ps: Here's a video I made on the project for lazy people who don't have time to read the article:

Supplies

A pair of broken QC25 (or QC35) headphones

A replacement driver: Amazon - https://amzn.to/2QTAL3o Ebay-

Glue

A Soldering Iron

A Hair Dryer

A Small Phillips Head Screwdriver

A Multimeter

Step 1: Gain Access to the Electronics

First, you need to remove the earpads as well as the felt covers to gain access to the screws holding down the metal covers of the headphones.

Removing the earpads is very easy - you just have to pull them under a slight angle and the plastic tabs holding the pads in place will pop out.

There are two screws for each cover. Put them somewhere safe, as you'll need them later!

Note: Of course, before beginning the teardown, make sure that the problem comes indeed from the headphones and not the cable (by trying a different cable or by doing a continuity test of the cable using a multimeter).

Step 2: Diagnosing the Speakers

To make sure that the problem comes indeed from the speakers and not the motherboard, you can measure their resistance by placing the probes of your multimeter set to ohmmeter mode on the terminals of the speakers (shown with a red arrow on the first picture). The polarity doesn't matter when doing the measurement.

A working speaker should have a resistance of around 32Ω.

However, a broken speaker has a resistiviry a lot higher than that: in my case, it was 2.04 kΩ.

If both speakers are fine, the problem comes from the motherboard - to find a replacement, the easiest way is to buy another pair of broken QC25's that have the opposite side broken. The working motherboard could then be salvaged and transplanted on the initial pair.

Step 3: Removing the Faulty Speaker

The covers on the speakers are solidly glued on. To remove them, you first need to remove the two screws holding the cover in place. Then, you can use a hair dryer to slowly soften the glue. After a minute, you can try to pull it away using a flat head screwdriver as a crowbar. Be careful not to damage the cover in the process, as you will have to glue it back on later.

DO NOT use a hot air gun to soften the glue. I did that on the first pair I tore down and the heat was too intense for the plastic - it made it shrink as you can see on the fifth image. Even if you keep the air gun far from the cover, it is too aggressive and difficult to control. Using a hair dryer is a lot safer and easier, as you can put it right next to the targeted area and the plastic won't shrink.

To remove the speaker, use the same strategy: hairdryer + gentle pulling with a screwdriver.

Step 4: Installing the New Speaker

If you managed to get to this step, congratulations! The difficult part is now over and the remaining steps are fairly easy:

First, get hold of a replacement speaker. You can salvage it from another pair of Bose headphones if you have a collection of them, or you can buy a clone from the web.

The sound quality won't match the original perfectly, but with the noise cancellation on the sound is already a bit distorted (making it difficult to tell the difference between the original and the copy). Sometimes you can also find legit replacements on eBay.

Installing the speaker is easy: just glue it in place and solder the wires back on.

Then, glue the plastic cover back on.

Finally, put the metal covers and the earpads back and you're done!

Step 5: Done!

Congratulations! You have now a working pair of noise QuietComfort 25's! By fixing the old pair you did not only save money but also helped keep our planet clean and fight against overconsumption!

I hope you learned something new along the journey.

If you liked this instructable please consider voting for me in the ''Fix it'' contest.

Thank you for reading and have a great day!