Libratone Track Air+ earphones
Wireless, Bluetooth earphones from late 2019 / early 2020, priced at around $200. It received positive reviews for both build quality and sound quality and they sound very good in my opinion. Actual build quality is debatable though - they tend to be a little bit fragile.
Common issue: broken stem. It looks like stem is glued or welded to the main part, but this is not a strong connection.
Often they can be glued back together with cyanoacrylate glue, but in this case flex PCB connecting these parts was torn, so they were not repairable,
at least not without a donor.
Apparently charger box is communicating with earphones using UART, probably in a unidirectional way (battery charging state + pairing request).
There is a magnet around the row of connectors.
There are two microphones inside stem, one of them seems to have analog output (only three lines).
Main part is glued, but after a bit of heating it was not difficult to open.
Main SoC: Qualcomm QCC5121.
LIR ZJ1254 55 mAh LiIon cell.
This was a big surprise for me. These earphones sound good and I've always associated it with large diameter transducers, but this capsule
has external diameter of 5.1 mm, similar to eartip head external diameter. On the other hand its depth is 4.0 mm. And another weirdness: it seems
to be acoustically connected partially to eartip head and to the hole next to it (visible on the picture with ear proximity window).
It turns out this kind of transducer is not that rare. Soundcore Life P2 has similar one, maybe 1 mm larger.
Semi-transparent window for ear proximity sensor.
Ear proximity sensor.
Pairing a new earphone (replacing broken one)
From libratone page:
Place both earphones in the charging case and press the function button twice briefly and then press and hold the function button until the LED flashes quickly (setup mode). So press three times and hold down the third time.
If this does not work the first time, please close the case and try the process again.
Then delete the old connection in the Bluetooth settings on your smartphone and reconnect the AIR+.
I've found this procedure little bit unreliable (maybe "briefly" should be more precise), but after few tries it worked.
Hard reset
Place both earphones in the case, press and hold the function button for approx. 5 seconds and connect the case to the power supply. (Press the setup button and plug in the cable at the same time) Now delete the TRACK Air/Air+ from the Bluetooth settings on your smartphone and pair the headphones again by opening the case and holding down the function button on the back for several seconds.
Factory reset
Place the two earphones in the case, briefly press the setup button on the back of the charging box once and then press it again and hold it down for 5 seconds. If the above steps do not work, try connecting the headphones to another device. Check whether the error also exists here.
Issues found
Upgrading firmware is necessary to unlock triple tap functions.
I was able to upgrade firmware of one of the repaired pairs, but not with the two other pairs. Application was not showing "search" icon next to firmware versions at all.
Application reinstall and clearing data/cache did not help. Maybe no one ever tested this application with more than one pair of headphones. I now have
a weird mix of v111, v124 and v127 (I'm assuming these are firmware version numbers). Service support is responsive, but I have some doubts if competent.
After asking about this issue I've received a reply stating that if update is not displayed, then earphones are running latest version. As I have three
different version does it really mean that there are three hardware versions?
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