Sony WF-C500 Teardown by 52Audio

Btw is anyone able to explain to me why a 300mAh internal battery is only able to provide 1 recharge for 2 earbuds with 70mAh batteries (total of 140mAh)? If the case was 100%, charged and you recharged completely discharged earbuds, would they use more than 140mAh to recharge them once? Is the recharge from the case battery not 1:1 to the earbud batteries? Are there losses, like from heat? If anyone can explain or link a video, that would be great.

Now onto the headsets, first looking at the top part with the button, we can see the antenna below the plastic button. The antenna does not appear to be printed onto the plastic like the WF-1000XM4 but instead looks like a ribbon cable antenna. I would imagine this is for cost savings, but if something would break, replacement would be much simpler here.

The PCB on the topside has the antenna connection and the tactile button. On the bottom left we can see the connection to the driver. The board looks to be held down by 1 philips head screw.

The top of the board has the main Bluetooth SoC, microphone for calls and the charging pins. The amount of components is comparable to the WF-XB700 but a lot less than say the WF-SP800N or even WF-H800. One thing I will point out, even though the model name for certifications is YY2952, the board still has the old HDX-2952 moniker, meaning internally Sony probably still uses HDX.

The driver is 5.8mm, as specified on the product specification page and also when 52Audio measured it. I understand this is a lower end device, but I feel Sony could have used a larger driver. One issue I noticed is that the driver is glued in or covered in some kind of epoxy to keep it in, so replacing it would require more effort. Likewise the wire connections look a bit fragile, so if you are taking it apart, be careful as not to rip them.