Fixing the Most Common Sony WH-1000XM4 Issues

This excellent guide is by antosaram from Reddit, with additional information by me, and from Sony's WH-1000XM4 service manual. Make sure to drop them a comment and like on their post on Reddit. The guide will cover 3 common issues:

1. Earpad replacement
2. High-pitch ANC noise 
   
3. Headband cushion replacement

Earpad Replacement

Step 1

Use a slim, non-sharp tool (ideally plastic, not metal) to gently unclip the old earpads around the edges. They should come off easily. 

Here is a photo from the service manual, which shows the position of the hooks or claws as Sony calls them. These claws are attached to the plate earpad, which can be felt on the outer lower edge of the earpads.

Here are the instructions from the service manual for removing the earpads.

Step 2

Remove the foam inserts, and clean out any dust inside the earcups. Sony calls the foam inserts "screens". I would recommend against washing the screens in water, but if you must, make sure they are 100% dry before reinstalling them. Another problem after washing might be that the foam pieces do not fit as they "grew" in size. To avoid this, just wash the foam pieces in water or minimize the amount of detergent you use. 

Step 3

Align the new earpads properly, ensuring each pin is in the right place. Then, press them down to securely snap them in.

Here are the steps from the service manual.

Step 1 - Click for larger size

 

Step 2 & 3 - Click for larger size

Step 4, 5, 6 - Click for larger size

Fixing ANC (Active Noise Cancellation) High-Pitch Noise

Over time, the feedback ANC microphones can accumulate dust, leading to an annoying high-pitched noise. The other issue is moisture damage to the electret mics. This is mostly due to sweat from the user and not outside moisture getting in. I am not sure if the feedforward microphones also suffer from this problem, but from the teardown, they seem rather protected from any external moisture to some extant.

Step 1

Remove the earpads and foam inserts. Use tweezers to carefully remove the gray rubber piece covering the ANC microphone.

 

 

This is how the microphone will look like without the cover.

Source: 52Audio teardown

Step 2

Lift the ANC microphone with tweezers. You will see a dark fabric filter—this collects dust over time, which may contribute to the high-pitch noise. I suspect moisture is the bigger issue here, rather than dust as antosaram has suggested. The point of the fabric mash is to keep both dust and moisture out of the electret mic. But in doing so, can collect dust and moisture, which can cause damage to the microphone.

Source: 52Audio teardown

You can see the fabric mesh piece in the photo above.

Step 3

Use 70% or higher isopropyl alcohol to gently remove the fabric filter. Take your time to ensure all glue and dust are completely removed. The microphone should look like this once cleaned. Allow a few minutes for the alcohol to fully evaporate before covering the mic with the cover.

Step 4

Repeat the same procedure for the other side. Next, reassemble everything. do not forget the grey piece covering the microphone. antosaram does mention that this repair may not solve the high pitch noise problem in all cases. If this is the case, then the probable cause of the noise would be damage to the electret mic, notably, moisture. antosaram said that they will post a separate guide on how to replace the microphone. 

Update: Unfortunately thanks to a comment from anonymous, the mic is not replaceable. As the service manual clearly states, in order to replace the mic, the entire side needs replacing.

It is not possible for replacement of left and right front plate portion, or replacement of electret cap microphone only. When the left and right front plate portion or electret cap microphone is defective, replace with the SV headphones assy (EXPLODED VIEWS: Ref. No. HPN1) including them.

Here are some tips to try and minimize this issue in the first place:

• After wearing the headset for extended periods of time, allow the inside of the earcups to air out and evaporate any moisture build up.
• Use Desiccant packs inside the earcups when storing them inside the case to absorb any excess moisture. They can be found on Amazon.
• I would recommend this for the WH-CH720N as well, as it uses an electret microphone for feedback NC.

Headband leather replacement

Buy a replacement on Amazon (black, silver, midnight blue), Aliexpress or other marketplace. antosaram bought theirs on Shopee( SE Asia). Aliexpress will be cheaper than Amazon, but I cannot recommend any listings on there.

Step 1

Remove the right earpad and foam inserts. Then, remove these four inner screws inside the right earcup. 

Step 2

Turn the headphones over and lift off the cover—it should come off easily. When taking the top off, please be careful as not to touch the area beside the red arrow. According to the service manual, this may affect noise cancellation performance.

Do not touch this, other side also has this "rear transistor"

Step 3

Disconnect the four connectors inside. Be careful with the thin ribbon cables, as they are rather fragile, especially the one from the battery, which is used to monitor the battery's temperature.

Step 4

Remove these two screws and gently lift the motherboard.

Step 5

Using tweezers, place the main cable (rectangular) under the motherboard. Then, remove the two hinge screws (circled in the image).

Step 6

Lift the loosened hinge and carefully unplug the second hinge using a plastic tool. Be gentle, the earcup should detach easily.

Step 7

Detach the plastic hinge from the main cable.

Step 8

Unclip the plastic plate from its narrowest side. Lift it gently from both sides. You’ll see adhesive underneath—this is fine and does not need replacing. Once the plate is off, remove the 2 screws  underneath.  

Step 9

Use tweezers to remove the plastic caps on the opposite side of the "WH-1000XM4" logo. Do this on both sides and remove the two screws on either side.

Step 10

Remove the old headband leather and install the new one. Take your time to ensure a proper fit.

Step 11

Reinstall the "WH-1000XM4" logo covers. These have plastic clips that help secure the leather, but you can also add a tiny piece of double-sided tape under the leather for extra hold.

Step 12

Reassemble everything by following steps 8 to 1 in reverse order. Ensure all connectors are properly plugged in, and the motherboard is seated correctly. If there is dust inside, clean it out.

When reinstalling the touchpad flex cable, make sure the line on the end of the connector is parallel to the port.

 Similarly, the flex cable for the termistor needs to be fully inserted like in the photo below.

For those wondering if the service manual has instructions for replacing the headband, no it does not. The service manual only shows how to replace the entire headband assembly along with the supports. Nothing about removing the cushion by itself. 

This is probably because Sony does not count the headband or earpads as serviceable items. Even though if you ask me, the headband should be covered. Imagine if Sony included an extra pair of earpaads inside the box with every headset they sold. This would be a major selling point. Alternatively, Sony should sell the replacement earpads and tips for earbuds on their site as accessories. and not through a supplier.

If anyone has any more guides, which they would want to share on the blog, please contact me.

If you want to have a look at the full service manual, iFixit has it on their site.