Sony WF-C700N FCC Teardown

 

Last week's announcement and release of the Sony WF-C700N, means that the external and internal photos on the FCC no longer need to be hidden. This means we finally get to see the internal design of the new model and to my surprise Sony opted for a much different design than I was expecting.

While this is not a full teardown like something from 52Audio, this is the best we have for now. For a comparison with the WF-C500, see here.

Starting off with the top removed, we can see a few things. The wireless antenna is integrated into the button, with the antenna contact visible near the top (gold stripe). Just like with the previous WF-C500, there seems to be some kind of plastic circular enclosure around the battery and main PCB. The microphone mesh/hole design is similar to the LinkBuds S. The microphone hole in the PCB is visible on the left of the photo near the top.

The other side photos are perhaps a bit sharper but show nothing else different. I am not sure if the plastic parts on the cover are white because this is the other side or if the unit is a pre-production one.

Removing the underside of the case reveals the battery. The WF-C700N lacks any wireless charging like its predecessor, but there is room for a wireless charging coil if Sony were to add one. Unlike the WF-C500, there is no sticker on the underside which means there are no screws holding the bottom half of the case to the main section. The attachment is via clips like the LinkBuds S.

And now for a closer look at the earbud PCB. I have numbered the various parts.

1. Bluetooth SoC - Airoha AB1562A

2. Unknown chip

3. Unknown chip

4. Battery protection chip

5. On board contact for wireless antenna

6. Main button

7. On board connector for flexible PCB

The red arrows on the left side show the on board contacts for the battery.

The other earbud PCB from the documents does not reveal anything else new. The major difference between the WF-C700N and WF-C500 PCBs is the absence of the charging contacts which have been moved off the PCB and onto the flex PCB. This can be seen below.

Left earbud

With every new headset, Sony is moving to a more minimal design and the WF-C700N is no different. Gone are any wires, replaced by a flex PCB which also contains other components which used to be on the main PCB, like the charging pins and MEMS microphone. The 5mm driver looks to be soldered to the flex PCB.

Right earbud

The right earbud shows the same details, and we can also get a good look at the magnet which helps align the headset in the case. The PCB design for this prototype was finalized on July 29th, 2022. The use of the flex PCB, along with the connector should greatly help with manufacturing and repairs.

The charging pins on the earbud PCBs are rarely labelled, and while we have corresponding pins on the charging case PCB, which are normally labelled, with the WF-1000XM4 and LinkBuds S, their charging case pin labels are covered by a plastic piece that surrounds the pins. Thankfully this is not the case with the WF-C700N, as the pins are labelled and visible.

The WF-C500 had a different order, the middle pin was the DET, and the outer 2 the GND (ground) and 5V. No idea why the change, but I am sure Sony has some valid reason. With the new WF-1000XM5, Sony has switched to only 2 charging pins. I am wondering why Sony did not use 2 pins here as well. I have some other brands use 2 pins for their earbuds, so it is nothing new. 

Next up we have the earbud battery. The new WF-C700N uses 2 different battery manufacturers, Springpower and VDL.

Springpower battery

VDL battery

Sony in the past has used 2 different battery suppliers for a headset but this is a first for earbuds I believe. The capacity is around 70mAh for both suppliers. The WF-C500 has the same capacity. The VDL coin cell is 3.85V, so perhaps it could be used in the WF-1000XM4 as battery replacement for the Z55H.

Moving to the charging case PCB, the design is similar to the WF-C500 and the new LinkBuds S. This side has the USB Type-C port and the button for pairing. At the bottom of the PCB is the LED which is visible on the front of the case.

The other side has the connections for the charging case battery, the charging pins, some small chips which are impossible to make one and the main large chip. This is the ABOV MC96F8216S microcontroller. This same chip was used in the WF-C500. It is unfortunate that the battery cables are soldered on and not attached via a connector. 

Turning to the battery, it is the same one as in the WF-C500, Springpower 300mAh/1.11 3.7V battery.

This same battery is used in the WH-C520 as well, so finding a replacement should not be that difficult.

And with that, this concludes the FCC teardown.

 

Update:

 

Thanks to a post on Instagram, we know the exact driver size, 5.5mm, versus 5.8mm on the WF-C500.  The specifications on the Sony site only state 5mm.

I am still testing my WF-C70N I bought last week, and so far I am quite happy with it. The sound quality is definitely improved, and the fit is comfortable. The noise cancellation could be better, but then there is only one NC microphone, so one cannot expect NC performance like the LinkBuds S or WF-1000XM4 with their dual NC.