Bangle.js 2 can't connect to bluetooth any longer

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  • Since a couple of days my Bangle.js can't connect to Bluetooth. I have tried both on my phone and in the browser (apps and IDE). It first started in Gadgetbridge (where it was previously connected), but when I was no longer able to reconnect I removed the clock and tried to add it again, without no luck.

    The device is discoverable (I can see it in my scans in both Gadgetbridge and in the browser), but I am not able to connect. I tried a factory reset, same issue. I also tried upload new firmware in DFU Mode, but the device just prints "connect" followed by "disconnect" a couple of times, see attached image.

    Anything else I can do?


    1 Attachment

    • 20240813-190749-176.png
  • Well, the fact it shows it's connecting is good really, it shows the Bluetooth radio is working.

    Any chance you can try rebooting your phone and trying again? Sometimes it's actually an issue with the connecting device's bluetooth (i know you did try two devices, but still it's worth giving it a go).

  • Hi @Gordon and thank you for your reply. I have restarted my phone, but still same behaviour when trying to connect as described above...

  • Sorry for the delay, I was away last week. So have you been able to attempt to connect with a device other than your phone?

    Out of interest, if you pinch hard in the top right-hand corner of the device while trying to connect, does it work? That's a sign of a hardware issue if so, but usually in the rare cases that happens the devices just don't appear on bluetooth at all unless pinched.

    And can your Bangle.js still boot, or did you firmware update attempt stop it from loading into Bangle.js (so it just stops at the bootloader)?

    I have had some devices having instability with Bluetooth because of an inaccurate oscillator and I did manage to improve that in recent firmwares, but I'm not sure the bootloader itself has that fix in. If you were able to get it booted as Bangle.js it might be possible to keep the connection active long enough that we could upload an updated bootloader, which would then allow you do connect and upload the updated firmware.

  • Hahaha, I felt so stupid when I pinched the upper right corner of the clock and tried to connect, BUT... It actually worked. After some attempts I was able to connect to the device again both with my computer and nRF tool to upload new firmware to the clock. After the firmware update I was able to connect it with Gadgetbridge again. So far, so good I guess :)

  • I am having some Bluetooth issues with my Bangle.js v2 as well with it not appearing on my Bluetooth scanner. I tried pinching the top-right corner of the screen fairly hard like you suggested and it occasionally appeared on the scanner. As soon as I released the corner, the Bangle would disappear. It would also sometimes drop off even with me pinching the screen corner, making it impossible to upload new firmware or set the time. Is there a good fix?

  • Ok, that's very interesting - and it stayed working for you after @rullen ?

    If pinching works, then there's definitely a hardware issue - there are two possibilities really:

    • The little spring contact that connects the PCB to the aerial inside the Bangle's case isn't making contact properly, which could be due to corrosion.
    • The actual nRF52 chip has come partially disconnected from the board

    If it's the second option, you're probably out of luck unless you want to reflow the board.

    But the first option, I'd suggest repeatedly squeezing the top right of the watch - it's possible that a bit of mechanical movement would wear off enough corrosion that you get a reliable connection again.

    If that doesn't work it'd be a matter of removing the LCD, taking the PCB off and cleaning the contacts on the PCB and watch case (maybe stretching the PCB contact to make it push harder), then sticking the LCD back on - there is a video on how to get the LCD off, but it is reasonably tricky.

  • Yes, it is working for me now after the pinching + firmware upgrade

  • Having Bluetooth problems as well; pinching did not do the job- I was successful with disassembling earlier and thought i would just need to repeat it. The heat sensitive glue B-7000 that I used to reseal was easy to "unglue" again. So far so good.
    Disassembled, did move the contact between the PCB and BT antenna as las time but this time I do not get stable contact reestablished.
    Any recommendation how to clean the contact? I did add a bit of aluminiumfoil in between but this did not help.
    Can I add some solder to the PCB spring or how do you deform the PCB contact to make stronger contact?

    or can I add conductive ink respectively graphite to keep the connection intact?
    Cheers, Gernot

  • There are various electrical contact cleaners available you could try? Like https://www.amazon.co.uk/WD40-Drying-Con­tact-Cleaner-250ml/dp/B00KPUBO2S/ref=asc­_df_B00KPUBO2S/ or https://www.henkel-adhesives.com/th/en/p­roduct/electrical-cleaners/loctite_sf_76­550.html - I keep one here and it gets used pretty often for household things.

    I'm not sure the aluminium foil is a good idea - the antenna would be tuned and it's possible that adding extra metal to it will mess up the tuning.

    If you look at the spring contact itself, you'll see there are two folded-in bits of metal on the side which stop the spring contact going out further. You can fold those out flat and then gently pull on the spring contact, and that should allow you to get it to out out further/with more force...

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Bangle.js 2 can't connect to bluetooth any longer

Posted by Avatar for rullen @rullen

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