Tear down of TaoTronics TT-BH07 Bluetooth Headphone

Overview

These are a pair of wireless bluetooth headphones I bought when I was training around in Japan a year ago. They were great initially giving great sounds quality with a decent balanced spectrum of sound and were great for calling people also.

Recently after not using these for several months the battery has gone dud. After 'fully charging' the batteries they only last for 5 minutes playing sound. This is likely because the batteries degraded, because they were left fully depleted for so many months. 

Tools required: just a craft knife

The 'buds'

Since the product is water resistant and seems reasonably well sealed it looks like the tear down will have to be a bit destructive. Firstly the disc shaped ends of each ear 'bud' were easily dismantled, doing some gentle prying with the craft knife. A magnet was found in each disc so they can easily 'clip' together. 

Just underneath this magnet revealed a small PCB for a SOT-23-5 LiPo PMIC covered in conformal coating to help with the water resistance I assume.  

The opposite end of each ear bud housing were more tricky to get apart, however a bit more persuasion with my craft knife did the trick and revealed a tiny speaker (5mm diam.) attached to the two blue & green signal wires coming from the main control module.

The control module

Yet again all of the housing for the control module was glued together. The two end caps could be popped off first, followed by prying open the housing with a craft knife. 

The inside revealed a very sleek tight PCB design on one side and the tactile buttons & a simple small light pipe on the other. The other side of the housing contained a small piece of marked foam pushed up against the MCU of the PCB to dampen any vibrations (which may also help the microphone performance?).

The Guts

- CSR audio SoC (https://www.qualcomm.com/products/csr8645. DS:http://www.czwtech.com/uploadfile/cfile/20121224103629171.pdf) w/ in-built LDO/SMPS

- FM24CL64B Cypress FRAM SOIC-8 (https://www.cypress.com/file/41656/download)

- Blue 2.4GHz antenna component. Likely has inbuilt bandpass filter for the ~2.4GHz. Ground stitching has been around the 

- Inductors (for PS or antenna or mic?)

- A microphone with marking (2008\n7936)

- Micro-USB port

 On the other side...

- R/B LED + transistor driver

- Snap dome buttons

- Potentially a MOSFET/diodes for the USB power?

The space constraint on this PCB is huge the DRC has allowed components to be extremely close to the edge of the PCB. I did often experience audible interference with the headphones whicch could be due to the smalll antenna configuration. Overall an extremely tight design and super well laid out boards.