Bangle 2 button not working properly -> disassembly?

The button of my bangle 2 from the Kickstarter campaign sometimes does not work properly.
The button was not reliable from the beginning, sometimes working good, sometimes only responding after special treatment (works better if pressure comes more from the back than from the side, ...). Fun fact: The behavior is not completely irregular. If the button works good, it stays this way for a while. Also if it's working bad, this also stays for a while, don't matter what i try to recover. Like some dirt flying around inside and sometimes blocking the button.
Sounds a bit like this thread: http://forum.espruino.com/conversations/370415/

I expected this to get better by time, or if not, i would have to open it and look after the button. Now id didn't get better, and looking closer at the watch i realized there is no 'easy to remove' back plate. Seems the watch must be entered from the front, removing the glass and then go forward...

Any idea how to open the device, or howto recover the button another way?

Maybe i searched the wrong part of the forum when i first searched for the button issue. After posting my question i found several posts addressing this issue, sorry for that.

Finally: Looks the only way to go inside is heating the front and removing the glass. When i do this to replace phone screens, i use about 80 degree hot air. What is the recommended temperature for the watch that will not harm the case?

No problem - I think the main post you're looking for is http://forum.espruino.com/conversations/372404

When i do this to replace phone screens, i use about 80 degree hot air. What is the recommended temperature for the watch that will not harm the case?

The case is ABS plastic so realistically as long as you're below 100 degrees C there's no real chance of damage (ABS usually melts as you get near 200 C)

edit: I just tried here with a dead one, being very liberal with the heat (heat gun set to 130'C), and the case was fine but the LCD wasn't. The datasheet for the LCD lists max 80 degrees C storage temp, or 70 degrees when working - so I would heat the glass up slowly, and try not to get much past 80.

The big issue is getting the LCD 'started' - because the plastic goes around the glass there's no way to get under the edge, so you need to use a suction cup.

But it might just be worth me sending you out a replacement...

I can try to fix it, and come back to the replacement if i mess it up. Sooner or later i'll have to try it anyway, to replace the battery.

:) Ok, thanks - sounds like a good plan!

Finally i found the time to fix my button. As expected, the button daughterboard was able to shift its position, and because of that the outside button sometimes missed the electrical button.
I wonder if something was missing in my watch, because i haven't found anything that would have held the button in position... In the end i glued a bit of plastic foam to the button, so that the display presses the button into position.

Because opening the watch was a bit challenging, here is a little howto: Disassembling of the bangle 2 display.

As stated, the display glass must be heatet to not much above 80° using ho air. I used hot air of 100°, first with some distance to the watch. I then checked the temperature of the glass surface from time to time using an infrared thermometer, reduced the distance step by step and tried to remove the display using a suction cup. When the glass surface reached 83°, the display started moving a bit when pulling. Here i kept the distance and repeated heating/pulling until the display glass came free.
Tipp: The display was glued in place with liquid glue that has hardened in the meantime. If the display has come loose at one point, it will not stick there again when you press on the display.
Tipp: The display will tell you its temperature by itself. At ~70° the display content starts fading away, at ~80° the display content has completely vanished.

To reassemble the display, i used standard double sided adhesive tape. I fear this is far less solid than the original glue, but makes service easier :-). I will report back if the display falls out at any point.

3 Attachments

That is excellent - thanks for the update, and glad you got it sorted!

I have in the past been impatient and used a higher temperature, and managed to break the LCD so it's worth not using more than 100 degrees :)

I think the button can be a mix - looking at the ones I had back, I had one where the PCB had shifted, but I've also had one where the button itself had totally disintegrated.

I pushed the manufacturer about the issues after the first batch, so I'm hopeful that the Bangles since the KickStarter will be a lot more reliable.

At ~70° the display content starts fading away, at ~80° the display content has completely vanished.

Nice job. So did the screen fully recover after cooling down? Same contrast/colors as before? The last photo looks still a bit pale.

The screen has fully recovered after cooling down.
The pictures got mixed during the upload. The last picture is actually the first one in order of disassembly, showing the display fading away during heating.
Picture order is 2-3-1.

I put mine on a 3D printer heatbed. At about 83° I was able to pull it open. Please start with 70° and slowly raise it to prevent a fire. Watch youtube videos of a burning smart phone battery - It's dangerous!
So. I dried mine and sealed it back with epoxy. My button is a bit hard to press now and the vibration is dead. 😟 But bluetooth is working and it's water proof now.

Great! Was yours definitely wet inside then?

I'm surprised about the vibration though - the motor is right in the middle of the PCB so I wouldn't have thought it would get knocked/damaged easily.

I might have dipped it in a pool of salt water. It was dry but there was a white dust coat on everything...
The motor got glued by the epoxy. I sort of flooded the watch with it.

Finally it turns out double sided adhesive tape wasn't strong enough in the end. My display came off without me noticing it, and now its gone. Funny when you look at the watch unsuspectingly and only see the inner electronics.

@Gordon: Do you actually sell spare parts? Especially Displays :-)?

@Alberich123
https://shop.espruino.com/accessories/banglejs-parts/banglejs2-lcd

Argh, what a pain! But yes, as @johan_m_o says we do finally sell spare displays :)

Thanks :-) Wasn't aware of the spare parts shop, have just ordered the display.

I got another watch, that showed the same problem again after a year and a 3rd one to use now. I opened the 2nd watch and it was not wet. The button just permanently toggles pressing for no reason. When I unplug the button from the pcb, it stops doing that. I fear that the button or it's board is.. not tough enough.
Is there a spare part button, I can get? I wish I could find a water proof button that sort of fits into the case...

Argh, sorry about that - I wonder if maybe the button PCB ends up not fitted in 100% straight and then the pressing slowly dis-assembles the button over time.

I do have some spare button PCBs I can send you - send me an email with your address and I'll get one in the post - but I couldn't get hold of many at all (I think I have around 10) so I'm not offering them in the shop or they'll all go!