Teardown: Cowin HE5A SportFree Active Noise Cancelling Wireless Bluetooth Earphones

It was only a few months ago in November I was reviewing the Cowin HE5A SportFree ANC Wireless Bluetooth Headphones. While I was generally satisfied with the compromises the package entailed, I did mention that the lack of protective casing could lead to the wires becoming snagged and or damaged.

Unfortunately, in just three months, the unit had began to fail with a popping sound in the right earpiece whenever I moved my head. Flexing the wire traced this fault back to the point where the wire joined the body of the unit. The lack of strain-relief appears to have allowed the wire to bend at extreme angles, which seems to have worn away the thin enamel insulation allowing occasional short-circuiting of the ANC microphone circuit resulting in a “pop” noise. When ANC is turned off, the popping disappeared.

While I did like the unit and used it every week-day in a careful manner, it seems that this is a design flaw which would manifest in a matter of time. As a result, I decided to do a destructive teardown of the unit, noting it was unlikely to be repairable due to the design. For this, a very fine T2 Torx screwdriver is required – luckily one is included in my Xiaomi Wiha screwdriver set.

Teardown

Removing the tiny screws is not sufficient to get in – it seems like each of the end pieces are glued into place as well, taking some leverage to free. A limited amount of free wire is “tucked” into each end.

However, there is no obvious way to slide out the PCB – it’s a very tight fit especially with the port and button protrusions. I had a feeling all the buttons had to be pressed and the port levered out of place to move the PCB. In the end, I turned destructive, pulling at the wires and eventually snapping all of them.

Finally liberated from its shell, but not before having the shell “crushed” in a vice for some additional headroom – the buttons are actually attached to the PCB. No wonder it didn’t want to slide out.

The tiniest of buckle type switches is soldered to the top side of the board, with a few test pads. The silkscreen labels the buttons – MFB presumably for “multi-function button”.

The rear of the PCB is where most of the action is – dated 27th July 2018, the PCB is marked HE5-BES2000IS-V3, and indeed, the unit is based on a Bestechnic BES2000 IC. Aside from that, it seems there is a lithium battery charger IC, a chip antenna and a MEMS microphone package for the handsfree feature.

Crushing the individual earpieces, we can see that the audio is generated by a dynamic driver.

In the rear of the earpiece is a marshalling board, which houses the SMD MEMS microphone used for noise cancelling.

With the brand cover removed, we can see the grille and the MEMS microphone in shot, along with a bar magnet that allows the earpieces to “clip” together.

The other shell, as expected, houses the Li-Poly cell, which is marked 165mAh. This corroborates excellently with the review measurement of 161-169mAh.

Conclusion

Cowin have done a lot to squeeze everything into such a tight space, which involves copious use of enamelled wires. Unfortunately, this is not particularly durable and with a lack of strain relief, it is possible to exceed the minimum bend radius of the wire in normal transporation which leads to eventual short circuiting at the joint. As a result, I cannot really recommend the unit anymore based on experiencing this fault.

The solution is based around a Bestechnic BES2000 chipset with a 165mAh battery (measured 161-169mAh in the review). It was shown that dynamic drivers are used with a MEMS package microphone for noise cancelling in each earpiece.

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